P0502

DIAGNOSTIC TROUBLE CODES P0500, P0501, P0502
Vehicle speed signal malfunctioning or not working at all

Fault Symptom.
The SHIFT UP lamp does not work (certain markets). Fuel shut-off in all gears. Low boost pressure in 3rd, 4th and 5th gears, manual gearbox.


Conditions.
- Brake pedal not operated
- Engine speed > 2000 rpm
- Boost pressure > 0.3 bar
- No speed signal for 4 seconds.

DIAGNOSTIC PROCEDURE

1. Checking The VEHICLE SPEED Signal
Connect the Scan Tool.
Select "READ FUNCTIONS".
Select "CAR SPEED".

Drive the car and compare the speed on the Scan Tool display with the speedometer reading.

If the readings coincide, continue with point 3.

If the readings do not coincide or are incorrect, continue with point 2.





2. Checking The Signal Voltage
Connect a breakout box (BOB).
Jack up the car at the front.
Start the engine, engage 1st gear and run it at about 20 km/h.

Take a voltage reading (AC) across pins 39 and 25 of the BOB.

Readings of about 6.5 V and about 15 Hz should be obtained.

If the reading is OK, continue with "Checking the voltage supply".

If the reading is not OK:
- Check the lead between pin 39 of the control module and pin 2 of the speedometer for continuity/shorting. The speedometer is located in the main instrument display panel.
- Check the speedometer.

Continue with point 3.

3. Final Check
Clear the diagnostic trouble code, drive the car on test and check whether the trouble code is generated afresh.

If the DTC is generated again, refer to Before Replacing A Control Module.

If the DTC is not generated again, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.