V6 Calibra
Traction Control


 
The Traction Control system fitted to V6 Calibra's is an 'early' type TC system. It uses three main components :
  1. The front ABS wheel speed sensors are used to determine individual wheel speeds.
  2. The Traction Control ECU controls triggering and testing of the TC motor/solenoid unit (TC butterfly valve).
    It communicates with the main Motronic ECU to determine engine operating conditions.
    It also has links to the main Motronic ECU in order to send fuel injection cut-off signal when TC is triggered.
  3. The Traction Control Motor is a valve/solenoid assembly placed inline with the Throttle Body. Its' operation is controlled by the TC ECU. When activated the throttle butterfly valve position is overridden and the air inlet tract is closed - cutting engine output.

 

Manufactured for Opel by Hella. Uses two microprocessor chips. Same system used in Astra, Cavalier and Calibra.

When the TC ECU detects differential front wheel speeds and decides they exceed its' predetermined limit, the TC Motor is activated and engine power is cut by effectively closing the throttle valve. The TC ECU also sends a signal to the main Motronic ECU instructing it to cut the injector pulse cycle. When the TC ECU is activating, the TC dash light will flash orange.

The TC system can be disabled using the override button.
The TC button (bottom of the centre console - in front of gear stick) toggles the TC system on and off. The TC status light (on the instrument panel) permanently illuminates orange when the TC system is switched OFF (or disabled due to fault detected in TC system).

When you turn on the ignition the TC system is tested. During this brief period the TC status light will illuminate orange for a second and then go out - indicating all is normal.

Unfortunately the V6 Calibra TC system is prone to problems. Traction Control will always break.... eventually. It is the way the Traction Control motor/solenoid unit is designed. It uses an electromagnetic valve which uses standard carbon brushes. These wear with time, or more specifically the number of TC valve motor operations. Even if you don't think your TC is engaged very often (so it can't wear much, right ?) you have to take into account that valve operation is fully tested every time you turn the ignition and moves inline with the throttle valve. There are other moving mechanical parts which are also prone to wear. That's why V6 TC units usually fail after three to five years operation. Sourcing brand new TC motor solenoids is difficult and expensive. Normal recommended price is around 500 !! and it is rare to find an agent/dealer who moves much from this price. Good luck finding a new one; and very good luck if you're buying second hand with what's out there these days.
There are other parts to the whole TC system. The front ABS wheel speed sensors, the Traction Control ECU and the wiring in-between. Faults with the wheel speed sensors should also cause an ABS fault light but there have been reports where different size front tyres (caused for example by under inflation) have resulted in a TC fault - suggesting that the TC is less tolerant of differential wheel speed difference problems than the ABS system.

Under certain conditions where there is a difference between the rolling diameters of the front wheels the TC may activate or may generate a TC fault light. This can happen where you have one new and one worn tyre, a puncture - travelling on the space-saver wheel or even just after fitting 4 new tyres. To minimise this effect the TC ECU features a 'learn' function to compensate under these conditions. The learning adjustment is only carried out under specific circumstances and may take some time to correctly set the adjustment factor. You can help out by providing the correct driving condition for TC 'learning' :


What are the signs of a failing TC motor/solenoid unit ? 
The TC light comes on 'by itself' while driving along. Stays on regardless of TC button presses. Is only reset when I turn the engine off, then on again.
When the TC fault light is illuminated for more than 20 secs a fault is logged and stored. If you have an early model V6 it may be possible for you to read out the TC ECU fault codes (see below), using the TC warning light,  by shorting out the correct pins using the 'paperclip test'. This doesn't work on mid & late model V6's; the only way of properly interrogating the TC ECU is 'through' the main Motronic ECU using a Tech1 or similar (coms via ALDL asynchronous bus to Motronic).
You can get a code 79 (full load inhibit error) when performing a conventional ECU paperclip test (on the main Motronic ECU) . This is caused by a faulty TC ECU.

Can the TC Motor/Solenoid be repaired ?
Well, technically YES or rather it's life can be prolonged.
Cleaning the TC motor/solenoid connector plug sometimes appears to help.
Also stripping the TC motor out and giving it a good clean can also provide a short term extension in life.
When attempting to fix a TC fault light observe the following:

If the unit has failed due to worn bushes/connections then the bushes can be replaced and the bad connections fixed. The problem is that you need a complete TC strip down and it's a very fiddly unit to reassemble correctly. In fact so much so that not many successfully recondition these units.
In the example below the TC unit was successfully repaired by replacing the bushes  with new items from here :
http://www.anglocarbon.com/

 

 
TC stripdown 1

TC stripdown 2

TC stripdown 3

TC stripdown 4

TC stripdown 5



Do I even need Traction Control ?
Only you can answer that. Do you fully understand what it does?, do you know how much a new unit costs (450 + VAT .. gulp!) ? 
It is a driver safety aid. It is used to allow the driver to push the vehicle to it's limits under challenging conditions and have the TC ECU automatically back things off (cuts throttle with sub-second timing) if you start to loose it (significant difference detected in front wheel speeds).
Significantly, in the case of the calibra V6 implementation, the TC valve saps high end bhp from the system by causing a minor restriction in the inlet tract. Replacement of the unit with a spacer can free up a few bhp (at best) by removing the butterfly valve restriction.
When a widened TC spacer is used in conjunction with a matched widened throttle body, noticeable power gains can be made; most significantly in throttle response.  There is no commercially manufactured Traction Control spacer that I am aware of. The easiest way is to make one out of a broken old TC motor or have on made at a small engineering firm. Disengaging the traction control using the override button will not reduce the inlet restriction; you need to fit a spacer in place of the TC valve to gain any benefit.

 
If yours is bust then you need to decide if you just live without it (not recommended - Fix it !) pull the bulb and maybe fit a spacer, try to repair it or have it repaired or even replace it with an expensive rare new unit which should be trouble free for another five years or so. 
Don't let your experience with theV6 TC put you off traction control  systems in general. The calibra system is effective when it works but more modern traction control systems use injection cycle interruption methods and being entirely electronic are not susceptible to mechanical wear related problems like this.


V6 Traction Control ECU & System Diagnostics :

 
   

Paperclip test:
Short pins
A and J on the ALDL diagnostic plug (upper corner of engine bay, near alarm horn)
 

## NOTE 1: This will only work on very early model V6 calibra's (93-94).
On later models there is no pin connector in the diagnostic plug at the "J" position.
TC fault communications can only take place across the ALDL asynchronous link through the main ECU.
In these cases TC fault codes can only be read using a Tech1, Tech2 or similar.

## NOTE 2: In the event of simultaneous ABS and Traction Control errors rectify the ABS fault codes first and this may clear the TC fault too.


Traction control fault codes
Apply paperclip across pins, start engine and read fault code out as number of flashes from the orange TC Status light on the dash. There is a short pause in flashes between numbers. The number '12'  is used as a separator code. If a fault code is stored it will be repeated three times before the separator code is shown (12) and then the next fault code is flashed out. The whole sequence cycles until you turn off the ignition.

10      TC ECU has not been coded for correct vehicle application (same ECU used for Astra, Cavalier and Calibra)
14     Coolant temperature sensor - voltage low (pass through signal from Motronic)
15   
 Coolant temperature sensor - voltage high (pass through signal from Motronic)
21    
not used for V6 Calibra
22     not used for V6 Calibra
23    
Throttle Position Sensor - load signal out of range (pass through signal from Motronic)
26    
TC valve position sensor - voltage high
27     TC valve position sensor - voltage low
31     No Engine RPM Signal (pass through signal from Motronic)
39    
LH Front Speed Sensor (pass through signal from ABS ECU)
42    
RH Front Speed Sensor (pass through signal from ABS ECU)
44    
LH Rear Speed Sensor (pass through signal from ABS ECU)
46    
RH Rear Speed Sensor (pass through signal from ABS ECU)
55    
Internal TC ECU fault
57     ABS status signal - low voltage (pass through signal from ABS ECU)
58    
ABS status signal - open circuit (pass through signal from ABS CEU)
61    
Throttle Position Sensor load signal - voltage low (pass through signal from Motronic)
62    
Throttle Position Sensor load signal - voltage high (pass through signal from Motronic)
63
    
TC motor/solenoid assembly - open circuit
64    
TC motor/solenoid assembly - short circuit
82     TC override dash switch - voltage low
 


Other Traction Control Facts

A common problem is the traction control motor plug becoming damp and/or the connector pins showing signs of green copper corrosion. A good clean and reseating the connector can fix this.



The TC system uses a pass through signal from the main Motronic ECU to determine the coolant temperature. This is used to help the TC ECU evaluate conditions. It only responds to five broad temperature band categories (see left) in respect to traction control response conditions.

 


If you are able to read them then fault codes: 39, 42, 44, 46, 57, 58 are faults with the ABS system not the traction control system and therefore the ABS light should be on. Fix the ABS fault and the traction control fault code should go away. Feedback from the ABS telltale input is requested by the TC ECU after completion of its' four second initialisation sequence (on ignition switch on).
Faults with the wheel speed sensors can and do occur. Electrical cable related faults are possible (between wheel speed sensor and connector) as are problems with the toothed target wheel the sensor keys off.

Intermittent cable related faults with either of the two front wheel speed sensors can cause the TC system to activate. The TC system can be deactivated with the override button until the ABS wheel speed sensor has been replaced.

Faulty front wheel speed sensors can cause erratic or failed Speedo reading on electronic Speedo equipped V6's (post '95).

Wheel speed sensors can be difficult to replace due to rusted sensor mounting brackets. Fortunately a new bracket and bolt only adds a few quid to the cost of a new ABS sensor.

It is rare to get a TC ECU failure (but not impossible). This appears to be the most reliable TC system component .