V6 calibra - Fuel Computer

V6 calibra : 
Fuel Computer Plug Pinout

1 ground (-). control unit terminal 6 14 voltage supply, terminal 30
2 ground (-) 15 instrument illumination brightness control
3 not used 16 not used
4 not used 17 not used
5 clock set minutes, control unit terminal 1 18 not used
6 fuel pump relay, terminal 87 or 87b 19 not used
7 not used 20 start key, control unit terminal 4
8 tank sensor (vectra LCD only) 21 odometer frequency sensor
9 diagnostic plug, terminal D 22 stepping key, control unit terminal 2
10 data line, ALDL diagnostic plug terminal G 23 clock set hours, control unit terminal 3
11 voltage supply (+), terminal 15 24 injection system or fuel flow control unit signal
12 ground (-), external temp sensor 25 ground (-) diagnostic plug terminal A
13 signal (+), external temp sensor 26 tank sensor - bimetal measuring device (calibra)


V6 Fuel Computer - Diagnostic Mode
originally from Andy Kirwan's pages

A fault code will be stored if an F is displayed. These can be read out from the fuel computer. Short pins A and D on the diag plug.
Switch on the ignition.
First 12 is flashed 3 times in the top display.
Then if a fault code is stored it will be flashed 3 times.
Otherwise - - - is flashed 3 times.

To clear the fault codes press the raised button


short pins D+A on diagnostic plug then turn on engine and note fuel computer display


Tank sensor voltage low short circuit


Tank sensor voltage high open circuit


Outside air temp sensor  short circuit


Outside air temp sensor open circuit
173 Fault with fuel signal from ecu

Other Modes can be selected by pressing the mode button

  • D1 fault code reading / clearing

  • D2 speed and fuel signal testing

  • D3 button testing

  • D4 Segment Test

  • D5 Fuel Tank sensor calibration


D2 Speed and Fuel signal testing

Select mode D2

‘S-‘ will change to ‘So’ when the MPH speed sensor is triggering. (drive the car)

‘E-‘ will change to ‘Eo’ when the ecu fuel signal is working (when you rev the engine)

D3 Button testing

Press the remaining 3 buttons. If all buttons work  - - -  will be displayed

D4 Segment check  (lam ps test) 

Hold down the button rear button in mode D4

All segments will be turned on so you can check for a faulty segment on the display

D5 Calibration of Range 

If you feel the range is not accurate you can adjust it.

Deviations of up to 3 litres can be adjusted for in 0.5 litre steps.

When correctly adjusted, the car should drive for 3 to 6 miles  before it runs out of fuel.

Select mode D5.

Press the hours pin.

A: should be displayed next to a positive or negative even number, this is followed by the range @ 28mpg.

The range can be adjusted from –A12 to A0 to +A12.

If the display says you have miles left and you believe you are about to run out of fuel then it should be adjusted in the negative direction.

If the display says you have 0 miles to travel yet you can drive over 6 miles then you should adjust it in the positive direction.

Use the mode button to select the A value you require. Then hold the raised button until - - - is displayed.

author : mark craft

How to find out what sensor is failing on your fuel computer by looking at what doesn't work any more
author : Andy Kirwan


Sensor Used


ECU (fuel)


Fuel tank sensor

Instant MPG




Average MPG




Average Speed





MPG ? or assumes 28.3 MPG


Outside temperature uses the outside temp sensor only. Located under the front passenger side of the bumper. Blue and Blue/white wires.

Instant MPG

If the ecu fuel signal is faulty the fuel computer will display 0.0 when the engine is running and stationary. If the speed signal is faulty, low values will be displayed in gal/hour and will not move into miles/gal when driving.

Average MPG

If the speed signal is faulty this will stay at --- or 0 when reset

Average Speed

If the speed signal is faulty this will stay at --- or 0 when reset


If the fuel tank sensor is faulty, the range will probably display --- when reset
The speed signal comes from a sensor mounted in the back of the speedo itself on early models. These are prone to failing.

Later models without mechanical speedo cables, the speed signal is derived from the ABS. Either the rear right or the front left wheel sensor. If this signal is faulty the speedo itself won't work either.

The fuel signal comes from the ecu. On V6 models this is across injector 1. 
The fuel tank sensor is the same one used for the fuel gauge.

Program Code

You do not require the diag link for this :

To check what your computer is setup for (engine, tyres, speed sensor, units miles/km) hold down both buttons. The Program memory code is displayed in the top window. This number should be the same as what is stamped on the vin plate on the bonnet slam panel. The number at the bottom right. ( last number in the ‘colour’ row.)

In the bottom window two letters and two numbers are displayed. The Alpha code represents what country it was made for, the language of the modes printed on the front and also the colour. The number is the version.


Once the buttons are released the bottom display displays what speed sensor the unit is setup for.
Pulse per/Km
6200    = 16200
= 16500
= 15458  (ABS)