V6 Calibra : Bosch Motronic ECU
based on original info from andy kirwan, mike warlow and topbuzz sites


V6 Calibra Bosch Motronic 2.8 ECU Variants

engine year immobiliser ident*  chassis no. Vaux part no's
(Bosch)
C25XE start > 1995 N PN  start production > T1999999  90357990 (0 261 203 080)
 90444156
(0 261 203 081)
 
90511010
C25XE 1995-1996 Y HE #  T1999999 to T9999999  90506364 (0 261 203 586)
 90510671
X25XE late '96 > end Y KC ##  V1000001 > end prod (V9004xxx)  90541689
 
90508770
(0 261 204 102)

ident* : two letter identifier code found on the Motronic case cover sticker
# ident
HE ECU supports immobiliser function
## ident
KC ECU supports immobiliser and secondary air injection system functions (Motronic plug pin 23 is occupied)


 

> Click for a full Listing of all the ECU's used in the calibra range <

 

V6 Calibra 'paperclip test' and Fault Code Tables

A : ground
B : ecu blink mode
C : auto transmission (*V6 option)
D : fuel computer
E : ecu warning light
F : 12v supply
G : 8192 asynchronous data stream
H : anti theft warning system
J : traction control (*very early V6's only??)
K : ABS system

 

diagnostic plug shown removed from its' socket

Example 'paperclip' test code:
read code from dash warning panel - engine management fault light (orange) - like reading Morse code:
.1.2.1.2.1.2.1.6.1.6.1.6.1.2.1.2.1.2.
(repeated...)
three 12's, three 16's, three 12's
so it's reporting a code 16 - front knock sensor fault

 

Interface : ALDL 8192 Baud asynchronous 5v- Pins A + G
used to connect to Tech1/2 or other compatible scanning tool

 
The "Paperclip Test" - So called because all you need is a bent paperclip to short two pins together in the diagnostic plug.
Diagnostic codes are flashed through the instrument panel warning lights.

Locate your diagnostic plug. Under the bonnet, upper right hand corner near the scuttle; next to the alarm horn.
Unplug the diagnostic plug from the socket holder.
Short pins
A + B in the plug as shown in the diagram
Turn on ignition and start the engine
The orange engine management fault light, in the dash, should flash with the fault code list.
Three 12's are the code separator so the list starts with three 12's and three 12's are used to separate each code. Each fault code is also repeated three times.

NOTES

# Mid & Late model calibra V6's (94 on) : all Traction Control ecu codes can only be read through main Motronic ECU via Tech1 reader. If this is the case you will not see a pin at position J

# Reset Fault Codes : Engine codes should disappear after the fault has been repaired and the car has been restarted 25-30 times / driven 200 miles. Alternatively you can disconnect the battery for 10 mins - 30 mins to clear all codes. Airbag light SRS fault can only be cleared with a dealer "Tech1" device. If you disconnect the battery for a prolonged period of time the ECU will need to "relearn" the cars specific settings again. Normal re-learn period is 200-250 miles

# Some faults will cause the ECU to go into a 'limp' mode. This is usually noticed by a big drop in performance and an imposed rev limit of around 3500/4000 rpm. The ECU does this as it believes it can no longer reliably monitor engine feedback and running using normal ECU maps could damage the engine. In this mode the ECU substitutes several live sensor values for safe defaults.

# 60% of all Motronic faults will be corroded, loose or bad wiring, dirty connections or just transient non recurring faults. The rest are usually genuine failed sensor/component faults. If you have multiple faults then always first check battery and alternator system also all earth points. Modern ECU's are sensitive to voltage supply level and quality; if there's a problem with supply then the ECU can kick up all sorts of apparently unrelated fault codes.

# Is your fault code related to any work recently carried out on your calibra. Could cables and connectors have been disturbed or even left disconnected. Replacing the alternator is a classic for causing a loose earth wire on the oil pressure gauge sender, for example (the jumping oil pressure gauge needle problem !).

 Calibra V6 (late RHD model)  Module Locations:

Motronic ECU :     Drivers footwell upper bulkhead
Traction Control ECU:  Bulge between passenger seat and passenger door
ATWS ECU :  Passenger footwell upper bulkhead
Check Control Unit :  For instrument cluster warning lights - behind glovebox
ABS ECU :  Engine bay - black box by ABS valve block
Airbag Control Unit:     Under console between front seats
Central Locking Control Unit:  Drivers footwell lower bulkhead
Fuel Pump Relay:   Drivers footwell lower bulkhead
Immobiliser ECU:  Underneath steering column

 


V6 Calibra - Known ECU & Sensor issues

Front Knock Sensor (code 16 or 17) - One of the most common V6 faults. First check and clean knock sensor connectors. Also check integrity of sensor - needs to be tightened to the engine block to the correct torque. This is important as the knock sensor is essentially a microphone designed to pick up on certain frequencies of engine vibration and alert the ECU. Bad wiring loom to knock sensor connector is also a common V6 fault; suspect this if all other trouble shooting has failed. Degraded loom causes signal loss. Replace loom from ECU to sensor connector (through bulkhead).
It has been reported that in some cases the front and back knock sensors are in the opposite order. In these cases a fault code 16 actually refers to the rear engine knock sensor (at back of engine back nearest windscreen). If unsure check by disconnecting each sensor in turn and driving as short distance to check which fault code has been triggered.

Traction Control - Failing TC motor/solenoid or bad connections/wiring. Check and clean connection to TC motor/solenoid. Clean TC valve and throttle body.

Oxygen/Lambda Sensor -
Installed in the exhaust down pipe this sensor measures the level of unburnt fuel in the exhaust stream and feeds this back to the ECU to help control fuelling (closed loop mode operation). Common fault code 13, 38 or 39, a failing sensor does not always cause a fault light as its' sensitivity fades slowly over time. Symptoms include poor fuel economy, running rich. Can cause mid range acceleration 'lags' where the engine feels like it is hesitating slightly only in mid range (also hesitates coming off the gas too). Lambda/Oxygen sensors are designed to fail; they need replacing every so often (5 to 7 years). Best to replace with genuine Bosch Oxygen sensor as some universal type oxygen sensors have been known to cause problems (continue to raise fault codes).

Mass Air Flow Meter/Sensor - V6 uses Hot tile type MAF. Much more reliable than hot wire type used on 16v calibras. code 73 or 74. Check and clean sensor connector first if you get fault code. Use of aftermarket air filters (which require oiling to filter correctly) can damage MAF. Over oiling the filter can cause hot tile to become contaminated and gives a poor response to air flow possibly leading to a fault code. Try cleaning hot tile very gently with some alcohol based cleaning agent. They don't last forever and can fail requiring replacement. Can check resistance response of sensor to diagnose total failure of this expensive part.

Coolant Temp Sensor - code 14 or 15. Sensor does degrade in signal response with time, a failing CTS does not always raise a fault code it just provides the ECU with an incorrect coolant temperature. Will eventually supply a bad reading out of ECU tolerance (which is when a code is raised). Symptoms can include poor start, rough idle and rich running/poor petrol economy.

Camshaft Angle Sensor (cam sensor) - code 93 and 94 can be listed as HALL EFFECT SENSOR faults but this refers to the CAS sensor as the DIS V6 doesn't have a traditional 'in-distributor Hall sensor). Once again the V6 version of this item appears to be vastly superior in reliability to that found on the 16v (where is it a very common 16v problem). Total cam sensor failures can occur, not often. Always check and clean connector first. Failures can sometimes be linked to recent cam belt replacement activity where sensor must have been 'disturbed'.

Crankshaft Sensor - code 19 and 31. Used by ECU to determine engine RPM. If you get a fault code related to RPM sensor then start the engine and try reading the codes again with the engine running (this will not cause any damage - codes were designed to be read with the engine running). Not a common genuine fault on the V6, but sensors can fail. As usual check and clean sensor connector first if a fault is suspected.

DIS Coil Pack & Ignition Amplifier - No relevant fault codes usually raised. It is rare for the ECU to be the cause of ignition problems. The V6 DIS coil pack units have a plastic casing, this can crack/micro-crack with age and heat. Symptoms can lead to misfiring on some cylinders, sometimes intermittent. Ignition amplifier is a small unit mounted at the back, and under, the battery tray. This powers the DIS unit and can fail causing loss of ignition power to one of the coil pack pairs.

Idle Speed Control Valve - Situated under the large V6 air intake manifold. The manifold must be removed to get at it. Much more reliable than that found on the 16v calibra - due to the better design of the V6 crankcase ventilation system. Idle Speed Control Valve solenoid may fail but this is unusual and does raise a code 56 or 57. Can suffer with dirty or loose electrical connector to the ISCV. May benefit from cleaning with carb cleaner if the valve gets sticky. Symptoms, unsurprisingly, are a rough 'hunting' idle speed.

Bosch Motronic 2.8 Fault Code Chart
specifically for Calibra V6 C25XE engines - compiled from several web sources

Code:

Item:

Fault:

13

Oxygen/Lambda/O2 sensor

No change in voltage/open circuit.

14

Coolant Temperature Sensor (CTS)

Low voltage

15

Coolant Temperature Sensor (CTS)

High voltage

16 Knock sensor 1 (front engine cylinder bank) No change in voltage, bad wiring or bad sensor

17

Knock sensor 2 (rear engine cylinder bank)

No change in voltage, bad wiring or bad sensor

18 Knock sensor fault in ECU Internal problem detected with knock signal processing functions

19

RPM signal (crankshaft sensor)

Incorrect RPM signal received from inductive pulse pick up sensor

21 Throttle position sensor High voltage

22

Throttle position sensor

Low voltage

25

Injector valve 1

High voltage

26

Injector valve 2

High voltage

27

Injector valve 3

High voltage

28

Injector valve 4

High voltage

29

Injector valve 5

High voltage

31

Engine RPM signal (crankshaft sensor)

No signal - engine not running (try reading codes with engine running)

32 Injector valve 6 High voltage

38

Oxygen sensor

Voltage low (weak mix detected)

39

Oxygen sensor

Voltage high (rich mix detected)

44 Oxygen sensor Lean Exhaust
45 Oxygen sensor Rich Exhaust
46 Secondary Air Pump Low Voltage
47 Secondary Air Pump High Voltage

48

Battery voltage

Low voltage

49

Battery voltage

High voltage

52

Check engine light

High voltage

53

Fuel pump relay

Low voltage

54

Fuel pump relay

High voltage

55

Engine Control Unit (ECU) fault

Renew Engine Control Unit (ECU)

56

Idle Speed Control Valve (ISCV)

Low voltage

57

Idle Speed Control Valve (ISCV)

High voltage

61

Fuel Tank Vent Valve (FTVV)

Low voltage

62

Fuel Tank Vent Valve (FTVV)

High voltage

69

Intake air temperature

Low voltage

71

Intake air temperature

High voltage

73

Mass Air Flow Meter/Sensor (AFM or MAF)

Low voltage

74

Mass Air Flow Meter/Sensor (AFM or MAF)

High voltage

75

Transmission switch Torque Control (auto box)

Automatic Transmission only

76

Continuous Torque Control (auto box)

Automatic Transmission only

79

Full load inhibit (Traction Control)

Incorrect ignition/injector cut-off / voltage low

81

Injector valve 1

Low voltage

82

Injector valve 2

Low voltage

83

Injector valve 3

Low voltage

84

Injector valve 4

Low voltage

85

Injector valve 5

Low voltage

86 Injector valve 6 Low voltage

87

Air Conditioning (AC) cut off relay

Low voltage

88

Air Conditioning (AC) cut off relay

High voltage

93 Hall Effect Switch (Camshaft Angle Sensor) Low voltage
94 Hall Effect Switch (Camshaft Angle Sensor) High voltage

97

Ignition/Injection cut-off (Traction Control)

High voltage

143

Immobiliser function in ECU

No or incorrect signal

144 Immobiliser no signal No signal received from immobiliser

145

Incorrect immobiliser signal received

Faulty unit or break in wiring

 


 

 

1

Ignition Signal to the coil/DIS  (output)
0 to 5 v DC switching signal
20 Ignition Signal to the coil/DIS (output) 38 Traction Control active signal (input)
2 Unoccupied 21 Ignition Signal to the coil/DIS (output) 39 To regional variant coding plug (looks like octane plug but isn't) (input)
wire: brown with green stripe (0.75mm)
3 Fuel Pump Relay ground pulse trigger signal (output)
wire : brown with blue stripe (0.75mm)
22 Engine Management Fault light (in dash) ground pulse trigger (output) 40 Air Con compressor input signal
4 Idle Speed Control Valve (ISCV) ground pulse trigger signal (output) 23 Secondary Air Injection pump ground pulse trigger (output) (late '96/'97 V6's only - KC type ECU) 41 Air Con readiness switch input signal (dashboard)
5 Carbon Canister / Fuel Tank Purge Valve ground pulse trigger signal (output) 24 shared ground (-)
ISCV, carbon canister vent valve, engine management light, fuel pump relay
42 Automatic Transmission Coding OR
Manual Transmission ground (-)
6 Unoccupied 25 Air Con relay 3 - ground pulse trigger (output) 43 Tachometer signal (sends out signal to rev counter) (output)
wire : solid green (0.75mm)
7 Mass Air Flow Meter signal (+input) 26 Unoccupied 44 Air Intake Temperature sensor signal (+input)
wire : blue with red stripe (0.5mm)
8 Camshaft Angle Sensor signal (+input) 27 ignition circuit voltage supply (+input) to Motronic ECU 45 Coolant Temperature Sensor signal (+input)
wire: brown with blue stripe (0.5mm)
9 Odometer Frequency signal to speedo (output) also used for immobiliser request/acknowledge
(input/output - asynchronous comms)
wire : blue with red stripe (0.5mm)
28 Oxygen / Lambda sensor signal (+input)
wire : brown with blue stripe (0.5mm)
46 Fuel Pump Relay ground pulse trigger (sent after immobiliser check passed) (output)
wire: brown with blue stripe (0.75mm)
10 Oxygen / Lambda sensor dedicated signal ground (-)
wire : brown with green stripe (0.5mm)
29 front Knock Sensor number 2 for cylinders 1, 3 and 5 (+input)
wire :
47 Unoccupied
11 front Knock Sensor number 1 for cylinders 2, 4 and 6 (+ input)
wire :
30 shared ground (-)
Air Intake Temp, CTS, TPS, MAF, Knock Sensors
48 (Crankshaft sensor) Inductive Pulse Pick-up sensor signal ground (-) used to detect actual RPM
12 5 volt DC supply to the Throttle Position Sensor(+ output) 31 Unoccupied 49 (Crankshaft sensor) Inductive Pulse Pick-up sensor signal ground (+input) used to detect actual RPM
13 to pin 'B' in diagnostic plug (initiate paperclip test) (input) 32 Unoccupied 50 Traction Control input signal to trigger ignition/injection cut-off in the Motronic ECU
14 ground for final fuel injection stages (-) 33 ground trigger pulse for injector 6 (output) 51 Load reduction signal from automatic gearbox ECU (input) / on manuals this is unoccupied
15 ground trigger pulse for injector 5 (output) 34 ground trigger pulse for injector 2(output) 52 Unoccupied
16 ground trigger pulse for injector 3 (output) 35 ground trigger pulse for injector 4 (output) 53 Throttle Position Sensor signal in (+input)
wire: brown with blue stripe (0.5mm)
17 ground trigger pulse for injector 1 (output) 36 Unoccupied 54 TPS signal pass through to auto gearbox ECU (output)
18 permanent power supply feed (+) from battery to ECU. Used to retain volatile memory contents (fault codes and block learn values) 37 voltage supply 12v DC (+input) from Fuel Pump Relay 55 BiDirectional (Asynchronous) ALDL communications bus connection (accessed via pin G in diagnostic plug)
(input/output)
19 shared ground (-)        

 


 

V6 Calibra
Full Fault Code Description Table

Fault Code + Description

Details + Notes

13 : O2/lambda sensor open circuit

 Fault is stored if:
  • Oxygen sensor voltage is in the range of 350 mV to 550 mV
    (Circuit interruption, oxygen sensor defective)
  • Above condition must be fulfilled for at least 2.5 s (i.e. Normal highly varying changes are not seen).

Conditions to enable trouble code recognition

  • The trouble code recognition is enabled, if the following conditions are fulfilled consecutively:
    1.) Coolant temperature is greater than 70 C (158 F);
    2.) Condition 1.) fulfilled for 3 min;
    3.) Engine load signal is greater than 1.5 ms;
    4.) After conditions 1.) to 3.) are fulfilled, waiting period of 5 s elapsed;
    5.) Following trouble code not recognised: 73, 74;

Replacement Value:

  • 450 mV (oxygen sensor closed loop control is disabled)

ECU Terminals:
28, 10

TEST:
0.1 to 1.0 v DC varying rapidly with accelerator

NOTES:
When the ECU is in O2 sensor open loop mode (for a prolonged period) you will notice a drop in fuel economy. Lambda/O2 sensors should be replaced every 5 years/50,000 miles. Their response often degrades over time. This results in poor fuel economy but may not necessarily be bad enough to fulfil the fault code recognition conditions as detailed above.

 

14 : Coolant Temperature Sensor - Voltage Low


Fault is stored if:

  • Coolant temperature is greater than 140 C (284 F)
    (Short circuit to ground)
  • 80 deg C should give ~ 1.3v
  • 110 deg C should give ~ 0.6v

Replacement Value:

  • Intake air temperature > 0.4 C (32.0 F):
    80 C (176 F) is used as replacement value
    Intake air temperature < 0.4 C (32.0 F):
    Intake air temperature is used as replacement value for 180 s after engine start, and after that back to 80 C (176 F).

Effect:

  • The learn functions (oxygen sensor control, idle air control and knock control) are locked and the last valid values are used for calculation.

ECU Terminals:
45, 30

TEST :
 20 deg C = 3.0 to 3.5 v DC
 80 deg C = 1.0 to 1.3 v DC

NOTES:
CTS faults can cause poor starting, poor running and bad fuel economy.

 

15 : Coolant Temperature Sensor - Voltage High


Fault is stored if:

  • Intake air temperature > -20 C (-4 F)
  • Coolant temperature < -35 C (-31 F)
    (Short circuit to voltage or circuit interruption)

Replacement Value:

  • Intake air temperature > 0.4 C (32.0 F):
    80 C (176 F) is used as replacement value
    Intake air temperature < 0.4 C (32.0 F):
    Intake air temperature is used as replacement value for 180 s after engine start, and after that back to 80 C (176 F).

Effect:

  • The learn functions (oxygen sensor control, idle air control and knock control) are locked and the last valid values are used for calculation.

ECU Terminals:
45, 30

TEST :
 20 deg C = 3.0 to 3.5 v DC
 80 deg C = 1.0 to 1.3 v DC

NOTES:
CTS faults can cause poor starting, poor running and bad fuel economy.

16 : Knock Signal Circuit 1
cylinders 2-4-6 (front)

 
Fault is stored if:
  • Engine speed is greater than 1400 rpm
  • Control sensor reference voltage for knock sensor is less than 20 mV
    (Value varies depending on the engine speed)
  • Knock sensor voltage is evaluated and produces an implausible resulting value for 20 consecutive checks (at 100 ms intervals)

Replacement Value:

  • Engine load signal is greater than 2 ms and coolant temperature is greater than 38 C (100 F):
    The control unit retards the spark timing by up to 13.5 Crank Angle for reasons of safety (Value of retard varies depending on the engine speed)

ECU Terminals:
11, 30

TEST:
Knock Sensor Active = 1 v DC (peak to peak)

> more info here <

 

17 : Knock Signal Circuit 2
cylinders 1-3-5 (rear)

 
Fault is stored if:
  • Engine speed is greater than 1400 rpm
  • Control sensor reference voltage for knock sensor is less than 20 mV
    (Value varies depending on the engine speed)
  • Knock sensor voltage is evaluated and produces an implausible resulting value for 20 consecutive checks (at 100 ms intervals)

Replacement Value:

  • Engine load signal is greater than 2 ms and coolant temperature is greater than 38 C (100 F):
    The control unit retards the spark timing by up to 13.5 CA for reasons of safety.
    (Value of retard varies depending on the engine speed)

ECU Terminals:
29, 30

TEST:
Knock Sensor Active = 1 v DC (peak to peak)

> more info here <

 

18 : Knock Control Module; Replace Electronic Control Unit (ECU)

 
Fault is stored if:
  • Coolant temperature is less than 38 C (100 F)

or

  • Engine load signal is less than 1.5 ms
    (Value varies depending on the engine speed)
  • Engine running in engine speed range 600 rpm to 5000 rpm
  • The ECU performs an internal knock sensor circuit test every 253 combustions. If this test is not passed, the trouble code is set (ECU fault).

Replacement Value:

  • Engine load signal is greater than 2.0 ms and coolant temperature is greater than 38 C (100 F):
    The control unit retards the spark timing by up to 13.5 CA for reasons of safety.
    (Value varies depending on the engine speed)

ECU Terminals:
Internal ECU Function Error: The ECU thinks that there's a problem with the internal Knock Sensor function block.

NOTES:
Disconnect battery (for at least 15 min) to clear fault codes.
Check and clean both knock sensor connectors in the engine bay.
Check knock sensor heads are tightened to the engine block to the correct torque (20 nm)
With the battery disconnected check main ECU plug for water ingress and corrosion on pins (interior drivers footwell).
Start the car, drive sensibly until engine is warm. Test engine through the gears and check for reoccurrence of fault code 18.
If this fault code persists suspect faulty ECU (fault on knock sensor signal input stage).

 

19 : Incorrect RPM Signal
Crankshaft Sensor


A bad RPM signal from Crankshaft Impulse sensor (inductive pulse pick up - P35). Sensor located at front bottom of engine block.

Fault is stored if:

  • Since ignition ON, there has been already one start with correct synchronisation
  • Engine speed is greater than 520 rpm
  • Incorrect engine speed signal recognised
    (intermittent problems, missing teeth, wrong reference point, incorrect gap position, etc.)

EFFECTS:
Current values are used for the mixture adaptation and demand adaptation.
Calculated values are used for idle control adaptation and characteristic curve adaptation.

ECU Terminals:
48, 49

TEST:
 cranking : 4v AC + (peak to peak)
 idle : 8v AC + (peak to peak)
 cruise : 14v AC + (peak to peak)

NOTES:
Check Crankshaft Impulse sensor and cable shielding. Sensor outputs AC pulse to Motronic ECU.

21 : Throttle Position Sensor (TPS) Voltage High

 

Fault is stored if:

  • Throttle position sensor voltage > 4.8 V  (Short circuit to voltage)

Replacement Value:

  • The ECU calculates with a throttle valve angle of 30 .
    Other functions recognise only partial load and full load.
    Recognition depends on the engine load, the engine speed, and the mass air flow meter signal.

ECU Terminals:
53, 12, 30

TEST:
Ignition on and leave engine off
Measure voltage across pins xx and xx on Motronic ECU or use piercing probe on cables xx and xx from TPS sensor connector.
Foot off accelerator pedal = 0.35 to 0.87 volts DC
Foot fully pressed down on accelerator pedal = 4.2 to 4.8 volts DC

 

22 : Throttle Position Sensor (TPS) Voltage Low

 

Fault is stored if:

  • Throttle position sensor voltage is less than 0.1 V
    (Short circuit to ground)

Replacement Value:

  • The ECU calculates with a throttle valve angle of 30 .
    Other functions recognise only partial load and full load.
    Recognition depends on the engine load, the engine speed, and the mass air flow meter signal.

ECU Terminals:
53, 12, 30

TEST:
Ignition on and leave engine off
Measure voltage across pins xx and xx on Motronic ECU or use piercing probe on cables xx and xx from TPS sensor connector.
Foot off accelerator pedal = 0.35 to 0.87 volts DC
Foot fully pressed down on accelerator pedal = 4.2 to 4.8 volts DC

 

25 : Injector Valve 1 Voltage High
26 : Injector Valve 2 Voltage High
27 : Injector Valve 3 Voltage High
28 : Injector Valve 4 Voltage High
29 : Injector Valve 5 Voltage High
32 : Injector Valve 6 Voltage High
 
Fault is stored if:
  • Final stage diagnosis in ECU (Short circuit to voltage)  fails

EFFECTS:
The defective injector is no longer actuated by the Motronic ECU. The other injectors function normally.

ECU Terminals:
injector1 : 17, 14
injector2 : 16, 14
injector3 : 35, 14
injector4 : 34, 14
injector5 : 15, 14
injector6 : 33, 14

NOTES:
Expected pulsed signals to injectors
(can be measured with a scope):
 timed pulse to injectors in milliseconds:
 cold cranking = 11 to 12 ms
 hot cranking = 3.1 + ms
 cold idle = 4.5 + ms
 hot idle = 3.1 to 3.3 ms

 

31 : No Engine RPM Signal
Crankshaft Sensor


Crankshaft Sensor - inductive pulse pick up sensor (P35)

Fault is stored if:

  • Ignition ON
  • Engine speed is less than 23 rpm
  • Following trouble codes not stored: 19
  • Since ignition ON, there has not yet been a start with correct synchronisation

EFFECTS:

  • Current values are used for the mixture adaptation and demand adaptation.
    Calculated values are used for idle control adaptation and characteristic curve adaptation.

ECU Terminals:
48, 49

TEST:
 cranking : 4v AC + (peak to peak)
 idle : 8v AC + (peak to peak)
 cruise : 14v AC + (peak to peak)

NOTES:
Trouble code 31 is always displayed when the ignition is switched on
. As soon as an engine speed signal is received from the inductive pulse pick-up sensor (crankshaft sensor)  on starting, the fault is deleted and does not remain stored if the system is intact .

 

38 : O2 Sensor Circuit Voltage Low

 

Fault is stored if:

  • Oxygen sensor voltage is less than 90 mV
    (Short circuit to ground)
  • Above condition must be fulfilled for at least 2.5 s .

Conditions to enable trouble code recognition

  • The trouble code recognition is enabled, if the following conditions are fulfilled consecutively:
    1.) Coolant temperature is greater than 70 C (158 F);
    2.) Condition 1.) fulfilled for 3 min;
    3.) Engine load signal is greater than 1.5 ms;
    4.) After conditions 1.) to 3.) are fulfilled, waiting period of 5 s elapsed;
    5.) Following trouble code not recognised: 73, 74;

Replacement Value:

  • 450 mV (oxygen sensor closed loop control is disabled)

ECU Terminals:
28, 10

39 : O2 Sensor Circuit Voltage High

 

Fault is stored if:

  • Oxygen sensor voltage is greater than 1100 mV
    (Short circuit to voltage)
  • Above condition must be fulfilled for at least 2.5 s .

Conditions to enable trouble code recognition

  • The trouble code recognition is enabled, if the following conditions are fulfilled consecutively:
    1.) Coolant temperature is greater than 70 C (158 F);
    2.) Condition 1.) fulfilled for 3 min;
    3.) Engine load signal is greater than 1.5 ms;
    4.) After conditions 1.) to 3.) are fulfilled, waiting period of 5 s elapsed;
    5.) Following trouble code not recognised: 73, 74;

Replacement Value:

  • 450 mV (oxygen sensor closed loop control is disabled)

ECU Terminals:
28, 10

44 : O2 Sensor Lean Exhaust


Fault is stored if:

  • Oxygen sensor integrator (internal control unit value for evaluation of oxygen sensor control) has exceeded upper limit of 1,2
    Air/fuel mixture constantly too lean

Conditions to enable trouble code recognition

  • Coolant temperature is less than 85 C (185 F)
  • Intake air temperature is less than 30 C (86 F)
  • Following trouble codes not stored: 73, 74
  • Engine load signal is greater than 0.8 ms
  • Above conditions must be fulfilled for at least 10 s .

ECU Terminals:
28, 10

45 : O2 Sensor Rich Exhaust

 

Fault is stored if:

  • Oxygen sensor integrator (internal control unit value for evaluation of oxygen sensor control) has fallen below lower limit of 0,8
    Air/fuel mixture constantly too rich

Conditions to enable trouble code recognition

  • Coolant temperature is less than 85 C (185 F)
  • Intake air temperature is less than 30 C (86 F)
  • Following trouble codes not stored: 73, 74
  • Engine load signal is greater than 0.8 ms
  • Above conditions must be fulfilled for at least 10 s .

ECU Terminals:
28, 10

46 : Secondary Air Pump


Secondary Air Pump - Voltage Low

Fault is stored if:

Final stage diagnosis in control unit fails
Short circuit to ground or circuit interruption - wiring or failed air pump

ECU Terminals:
23

TEST :
Check: Interruption of Voltage Supply Circuit

  • Ignition OFF
  • Remove electrical component from socket: K12 Relay - Secondary Air Injection
  • Turn Ignition ON
  • Measure voltage between the following terminals:
    K12 Relay - Secondary Air Injection Socket Terminal
    4 ("+") & Ground (vehicle body "-")
  • Signal should be  greater than 11 v DC
  • If not check wiring, replace air pump
47 : Secondary Air Pump


Secondary Air Pump - Voltage Low

Fault is stored if:

Final stage diagnosis in control unit fails
Short circuit to voltage - wiring or failed air pump

ECU Terminals:
23

TEST :
Check: Interruption of Voltage Supply Circuit

  • Ignition OFF
  • Remove electrical component from socket: K12 Relay - Secondary Air Injection
  • Turn Ignition ON
  • Measure voltage between the following terminals:
    K12 Relay - Secondary Air Injection Socket Terminal
    4 ("+") & Ground (vehicle body "-")
  • Signal should be  greater then 11 v DC
  • If not check wiring, replace air pump
48 : Battery Voltage Low


Fault is stored if:

  • Engine not in operating condition: Start
  • 180 s elapsed time since engine start
  • Battery voltage is less than 10 V

EFFECTS :

  • The ECU compensates for the effect of the battery voltage to a certain extent.
  • The learn functions (oxygen sensor control, idle air control and knock control) are locked and the last valid values are used for calculation.
  • You can get all sorts of strange electrical problems if the voltage supply is too low. Expect spurious sensor faults.

ECU Terminals:
37, 19

See Battery Test Procedure

NOTES:
Low voltage usually results from a failed alternator or faulty battery. If the alternator is not charging then renew. If the battery is not holding charge then it's a new battery required.

49 : Battery Voltage High


Fault is stored if:

  • Battery voltage is greater than 16 V

EFFECTS :

  • The ECU compensates for the effect of the battery voltage to a certain extent.
  • The learn functions are locked and current values are used for calculation.
  • High voltages

ECU Terminals:
37, 19

See Battery Test Procedure

NOTES:
High voltage usually results from a failing alternator and/or faulty battery. If the alternator is identified as faulty (with high voltage) it is highly recommended to change the battery for new as well as the alternator. It may be possible to repair the alternator (replace voltage rectifier) but a new or reconditioned unit is recommended.

52 : Telltale (check light unit) Voltage High

 


Fault is stored if:

  • Final stage diagnosis in control unit fails due to a high supply voltage
    Suspect short circuit to voltage

ECU Terminals:
22, 24

NOTES:
High supply voltage has disabled the ABS ECU, Airbag ECU or main Motronic ECU. Check if ABS and Airbag instrument light 'tell tales' briefly illuminate and are then extinguished on star up. If not investigate supply to the one which isn't working.

53 : Fuel Pump Relay Voltage Low


Fault is stored if:

  • Final stage diagnosis in control unit
    (Short circuit to ground)

ECU Terminals:
3, 24

54 : Fuel Pump Relay Voltage High


Fault is stored if:

  • Final stage diagnosis in control unit
    (Short circuit to voltage)

ECU Terminals:
3, 24

55 : Fault with Electronic Control Unit (ECU)


Fault is stored if:

  • ECU hardware failure (EPROM / ROM defective)
  • Fault detected during Motronic ECU start up self diagnostics.
  • Serious fault was detected during last run causing Motronic to shutdown.

NOTES:
The normal ECU functions are carried out as far as possible but this code is logged when the Motronic encounters a serious error.

56 : Idle Air Control Valve - voltage high


Fault is stored if:

  • Short circuit to voltage (+) detected

ECU Terminals:
4, 24

EFFECTS :
The ECU learn functions for Oxygen Sensor, Idle Air Control and Knock Sensor are locked at the last 'good' values used.

TEST:
Check that the idle air control valve is getting a 12v feed. Disconnect the plug from the idle valve. Test for 12v between pin 2 inside the plug and vehicle earth (ground).

NOTES:
Remove and clean ISCV (Idle Air Control Valve) and clean out the attached length of rubber hose. Clean with "carb cleaner" or similar solvent. Valve is known to become sticky and resistant to movement.

57 : Idle Air Control Valve - voltage low

 

Fault is stored if:

  • Short circuit to ground (-) or break in wire detected

ECU Terminals:
4, 24

EFFECTS:
The ECU learn functions for Oxygen Sensor, Idle Air Control and Knock Sensor are locked at the last 'good' values used.

TEST:
Check that the idle air control valve is getting a 12v feed. Disconnect the plug from the idle valve. Test for 12v between pin 2 inside the plug and vehicle earth (ground).

NOTES:
Remove and clean ISCV (Idle Air Control Valve) and clean out the attached length of rubber hose. Clean with "carb cleaner" or similar solvent. Valve is known to become sticky and resistant to movement.

 

61 : Fuel Tank Vent Valve - voltage low

 

Fault is stored if:

  • Short circuit to ground

ECU Terminals:
5, 19

TEST:
Check for voltage supply to valve. Disconnect the wiring plug from the valve assembly. Measure voltage between pin A inside the plug and vehicle body (ground). Should be > 11 v DC.

NOTES:
Test using Tech1/2 - Fuel Tank Vent Valve actuator test
The tank vent valve is actually a carbon canister purge valve as this is where the fuel tank vent routes through. It is located under the alternator cooling fan ducting; the carbon canister is mounted up in the drivers side wing, behind the wheel arch cover.
When the controlled carbon canister purge valve is opened the engine is supplied with additional fuel (provided there is adequate fuel vapour already stored in the carbon canister). This can result in brief oscillations in engine rpm.

62 : Fuel Tank Vent Valve - voltage high
 

Fault is stored if:

  • Short circuit to positive (battery live)

ECU Terminals:
5, 19

TEST:
Check for voltage supply to valve. Disconnect the wiring plug from the valve assembly. Measure voltage between pin A inside the plug and vehicle body (ground). Should be > 11 v DC.

NOTES:
Test using Tech1/2 - Fuel Tank Vent Valve actuator test
The tank vent valve is actually a carbon canister purge valve as this is where the fuel tank vent routes through. It is located under the alternator cooling fan ducting; the carbon canister is mounted up in the drivers side wing, behind the wheel arch cover.
When the controlled carbon canister purge valve is opened the engine is supplied with additional fuel (provided there is adequate fuel vapour already stored in the carbon canister). This can result in brief oscillations in engine rpm.

69 : Air Intake Temperature - voltage low

 

Fault is stored if:

  • Short circuit to ground OR engine air intake temperature > 140 degrees C

EFFECTS:
ECU uses -33 deg C as a substitute value.
The learn functions (oxygen sensor control, idle air control and knock control) are locked and the last valid values are used for calculation.

ECU Terminals:
44, 30

TEST :
Use multi-meter to measure voltage between pin 1 in the connector socket (not the sensor pin) and the vehicle body (ground). Reading should be between 4.8 and 5.2 volts (DC) with the engine running

71 : Air Intake Temperature - voltage high

 

Fault is stored if:

  • Short circuit to ground OR engine air intake temperature < -35 degrees C

ECU only checks Air Intake Temp after the first 180 secs of engine running time

EFFECTS:
ECU uses -33 deg C as a substitute value.
The learn functions (oxygen sensor control, idle air control and knock control) are locked and the last valid values are used for calculation.

ECU Terminals:
44, 30

TEST :
Use multi-meter to measure voltage between pin 1 in the connector socket (not the sensor pin) and the vehicle body (ground). Reading should be between 4.8 and 5.2 volts (DC) with the engine running

73 : Mass Air Flow Sensor - voltage low
 

Fault is stored if:

  • Engine is not starting up
  • RPM > 520
  • Mass Air Flow Meter signal < 3 kg/hr (equivalent)

In this mode the ECU now ignores the AFM signal and uses a set of replacement values based on engine RPM and Throttle Valve Position Sensor signal. This will cause a noticeable drop in performance with the engine feeling more 'hesitant'.

Check wiring loom for short to ground and AFM connector for poor connection. May indicate failure of Mass Air Flow Meter.

ECU Terminals:
7, 30, 37

NOTES
The V6 uses a Hot Film Type Mass Air Flow Meter - utilises ceramic tile.
This is more reliable and causes less restriction than the 8v/16v hot wire type.
If AFM and TPS signals are both bad the ECU uses only two replacement values based solely on engine RPM.

  • Engine under load and RPM < 2000   -   3.0 ms is used
  • Engine under load and RPM > 2000   -   4.5 ms is used

TEST:
Disconnect plug to
mass air flow sensor
Engine running at idle speed & engine run up to normal operating temperature.
All electrical consumers turned off (stereo, fan, heater etc).
Accelerator pedal not actuated (foot off accelerator).
Measure reading between pin 3 (+) inside the mass air flow sensor plug (loom side) and vehicle ground (-). Normal feed value > 11 v DC
Power to pin 3 is routed through the Fuel Pump Relay.

Also possible to intercept return signal to ECU using piercing probes between pins
2 (-) and 4 (+) on the Mass Air Flow Meter. Normal idle value is between 0.56 and 0.86 volts DC.
This equates to 8 - 18 kg/hr air mass flow.
Snap accelerate should see the voltage rise > 3 v

74 : Mass Air Flow Sensor - voltage high
 

Fault is stored if:

  • RPM < 6520
  • Mass Air Flow Meter signal > 590 kg/hr (equivalent)

In this mode the ECU now ignores the AFM signal and uses a set of replacement values based on engine RPM and Throttle Valve Position Sensor signal. This will cause a noticeable drop in performance with the engine feeling more 'hesitant'.

Check wiring loom for short to ground and AFM connector for poor connection. May indicate failure of Mass Air Flow Meter.

ECU Terminals:
7, 30, 37

NOTES:
The V6 uses a Hot Film Type Mass Air Flow Meter - utilises ceramic tile.
This is more reliable and causes less restriction than the 8v/16v hot wire type.
If AFM and TPS signals are both bad the ECU uses only two replacement values based solely on engine RPM.

  • Engine under load and RPM < 2000   -   3.0 ms is used
  • Engine under load and RPM > 2000   -   4.5 ms is used

TEST:
Disconnect plug to
mass air flow sensor
Engine running at idle speed & engine run up to normal operating temperature.
All electrical consumers turned off (stereo, fan, heater etc).
Accelerator pedal not actuated (foot off accelerator).
Measure reading between pin 3 (+) inside the mass air flow sensor plug (loom side) and vehicle ground (-). Normal feed value > 11 v DC
Power to pin 3 is routed through the Fuel Pump Relay.

Also possible to intercept return signal to ECU using piercing probes between pins
2 (-) and 4 (+) on the Mass Air Flow Meter. Normal idle value is between 0.56 and 0.86 volts DC.
This equates to 8 - 18 kg/hr air mass flow.
Snap accelerate should see the voltage rise > 3 v

75 : Torque Control - voltage low
AUTO TRANSMISSION
 

Fault is stored if:

  • Time period > 30 ms
  • OR
  • Load Reduction Ignition Retard signal has been triggered three times for longer than 2.5 s

EFFECT:
In this fault mode the ECU will not adjust ignition timing when shifting gear

ECU Terminals:
19, 51

76 : Continuous Torque Control
AUTO TRANSMISSION

Fault is stored if:
  • "Torque control/ignition retard" signal is active 3 times for longer than 2.6 s
    (Engagement time too long)

EFFECT:
No further ignition retard during shifting on Automatic Gearbox.

ECU Terminals:
19, 51

 

79 : Full Load Inhibit - voltage low
Traction Control
 
 

Fault is stored if:

  • Ignition/Injection cut off signal from Traction Control ECU is present for longer than 0.2 seconds
  • Full load prohibition signal from Traction Control ECU is not once recognised during the expected time period
  • OR
  • Ignition/Injection cut off signal from Traction Control ECU has a short circuit to battery voltage (+)

NOTE
After each engine start the ECU monitors the signals on terminal 38 (Full load prohibition signal) and terminal 50 (injection/ignition cut off signal). The Traction Control ECU sends test signals to these Motronic main ECU inputs as part of its start up checks. If the Motronic ECU receives both OR neither of these two test signals then this is considered normal and evaluated as "Traction Control ECU OK - pass start up test".
If only one of the two test signals are recognised then the Engine Management fault light is illuminated.

If the ECU is in fault mode (EM light on) because of an fault code 79, then the full load inhibit signal is ignored completely.

ECU Terminals:
38, 50

81 : Injector Valve 1 - voltage low
82 : Injector Valve 2 - voltage low
83 : Injector Valve 3 - voltage low
84 : Injector Valve 4 - voltage low
85 : Injector Valve 5 - voltage low
86 : Injector Valve 6 - voltage low

Fault is stored if:
  • Final stage diagnosis in ECU fails (Short circuit to ground or circuit interruption)

EFFECTS:
The defective injector is no longer actuated by the Motronic ECU. The other injectors function normally.

ECU Terminals:
injector1 : 17, 14
injector2 : 16, 14
injector3 : 35, 14
injector4 : 34, 14
injector5 : 15, 14
injector6 : 33, 14

NOTES:
Expected pulsed signals to injectors
(can be measured with a scope):
 timed pulse to injectors in milliseconds:
 cold cranking = 11 to 12 ms
 hot cranking = 3.1 + ms
 cold idle = 4.5 + ms
 hot idle = 3.1 to 3.3 ms

87 : Air Con cut-off relay - voltage low

Fault is stored if:
  • Final stage diagnosis in control unit fails
    (Short circuit to ground - circuit interruption)

ECU Terminals:
25, 19

NOTES:
Check Air Con compressor relay (K60)

88 : Air Con cut-off relay - voltage high

Fault is stored if:
  • Final stage diagnosis in control unit fails
    (Short circuit to voltage)

ECU Terminals:
25, 19

NOTES:
Check Air Con compressor relay (K60)

93 : Hall Sensor - voltage low
CAMSHAFT ANGLE SENSOR (P47)


Fault is stored if:

  • Recognition of more than one phase information during one work cycle with correct reference mark on cam (Short circuit to ground)
  • Above condition must be fulfilled for at least 40 times.

EFFECTS:
Engine load signal is greater than 3 ms and coolant temperature is greater than 38 C (100 F):
The control unit retards the spark timing by up to 10.5 CA for reasons of safety.
(Value varies depending on the engine speed)

The "Hall Sensor" on the camshaft is used for cylinder recognition. It informs the Motronic ECU of the camshaft position when cylinder 1 ignites. The ECU needs this information for accurate fuel injection control and for adaptive knock control. If the Hall sensor malfunctions the ECU attempts to use a random time for injector/spark actuation. This can cause a poor or non-starting engine.  If the engine does start with a malfunctioning cam sensor then expect very poor economy.

ECU Terminals:
8, 19, 37

TEST:
with engine running 2.5v DC (average)

94 : Hall Sensor - voltage high
CAMSHAFT ANGLE SENSOR (P47)

 

Fault is stored if:

  • Recognition of more than one phase information during one work cycle with correct reference mark on cam (Short circuit to ground)
  • Above condition must be fulfilled for at least 40 times.

EFFECTS:
Engine load signal is greater than 3 ms and coolant temperature is greater than 38 C (100 F):
The control unit retards the spark timing by up to 10.5 CA for reasons of safety.
(Value varies depending on the engine speed)

The "Hall Sensor" on the camshaft is used for cylinder recognition. It informs the Motronic ECU of the camshaft position when cylinder 1 ignites. The ECU needs this information for accurate fuel injection control and for adaptive knock control. If the Hall sensor malfunctions the ECU attempts to use a random time for injector/spark actuation. This can cause a poor or non-starting engine. If the engine does start with a malfunctioning cam sensor then expect very poor economy.

ECU Terminals:
8, 19, 37

TEST:
with engine running 2.5v DC (average)

97 : Ignition/Injection cut-off signal - voltage high
 

Fault is stored if:
Ignition/Injection cut-off signal from Traction Control ECU is present for > 2.5 seconds.

EFFECTS:
If this fault is recognised then full load inhibit signal is ignored completely by the ECU until fault condition has cleared.

NOTES:
After each engine start the ECU monitors the signals on terminal 38 (Full load prohibition signal) and terminal 50 (injection/ignition cut off signal). The Traction Control ECU sends test signals to these Motronic main ECU inputs as part of its start up checks. If the Motronic ECU receives both OR neither of these two test signals then this is considered normal and evaluated as "Traction Control ECU OK - pass start up test".
If only one of the two test signals are recognised then the Engine Management fault light is illuminated.

ECU Terminals:
38, 50

143 : Immobiliser - No or Wrong coding

Fault is stored if:
  • Engine management light flashes and car won't start - Wrong coding - Immobiliser function has been coded incorrectly.
  • Engine management light flashes and car will start - No coding. i.e. the immobiliser function has been disabled using a Tech1 or it's a new ECU which is always delivered with the immobiliser function off.

ECU Terminals:
9 - ECU immobiliser function uses vehicle speed sensor signal wire (which is routed through the immobiliser control unit) to request confirmation from the immobiliser control unit.

Notes:
A new request is only sent on ignition on if the prior ignition off period is greater than 12 seconds (amount of time taken for Motronic to power down fully after ignition off)

144 : Immobiliser - No Signal

Engine management light flashes and car won't start (will start if immobiliser ECU function block disabled/reprogrammed with Tech1 or correct immobiliser received)

Fault is stored if:
Either the ECU does not recognise the signal format being sent from the immobiliser
OR
There is no signal coming from the immobiliser

NOTES:
If the car will not start check that you are not using the spare key with no transponder chip in the fob.
Check wiring between immobiliser unit and ECU. Check operation of Vehicle Speed Sensor wiring. Is the speedo working (late model V6's with electronic speedo)?

145 : Immobiliser - Wrong Signal
 

Engine management light flashes and car may not start or will start but faulty speedo.

Fault is stored if:
The immobiliser signal sent to the ECU is the correct format but it's the wrong transponder coding. Intermittent faulty wiring/connectors on speedo circuit.

NOTES:
If the car will not start check that the transponder chip is in the fob and intact. Check immobiliser transducer pick up unit (plastic ring unit around ignition barrel).
Check wiring between immobiliser unit and ECU. Check operation of Vehicle Speed Sensor wiring. Is the speedo working (late model V6's with electronic speedo)?

 


 

Battery test procedure
measure voltage across battery terminals with battery tester or multi-meter

Ignition On
Engine not running
All electrical consuming devices turned off

 11.5 to 13.5 volts DC

Engine starting (cranking)

 8.0 volts DC or greater

Engine running (at idle speed - 700-800 rpm)
All electrical consuming devices turned off

 12.0 to 15 volts DC

Voltage between ECU pin ground points and chassis earth points should normally be within 0.25 - 1.25 v DC.

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