P0502

VEHICLE SPEED SENSOR





Symptom Of Fault.
SHIFT-UP lamp out of order.
Fuel shut-of in all gears.
Low boost pressure in 3rd, 4th and 5th gears, manual gearbox.
ABS warning lamp may be on.

Conditions.
^ P0500: All-embracement DTC.
^ P0501: ignition switch in ON position.
vehicle speed >270 km/h.
^ P0502: brake pedal not depressed.
engine speed >1800 rpm.
intake manifold pressure > 60 kPa.
no vehicle speed signal for 4 seconds,

Above conditions fulfilled and then no vehicle speed signal for 17 minutes.

Diagnostic Help.
A vehicle speed signal reading can be obtained on the ISAT scan tool.

- Select "READ FUNCTIONS".
- Select"CAR SPEED".

The ISAT scan tool should show the current wheel speed.

Drive the car and compare the ISAT scan tool reading with the speed indicated on the speedometer.

Checking The Wiring
Intermittent faults may occur as a result of occasional short circuits and breaks in the wiring. Jiggle the leads and line connectors at several places and in different directions to reveal faults in the wiring harness. Observe the multimeter, ISAT scan tool or test lamp while carrying out this check.





Diagnostic Procedure.
1. Check the ABS diagnostic trouble codes
- Connect an ISAT scan tool.
- Ignition switch in ON position,
- Select "ABS M96".
- Obtain readouts of any diagnostic trouble codes.

Relevant diagnostic trouble codes for the RH front wheel sensor are B1376 and B1377.

Is B1376 or B1377 present?
YES: Continue fault diagnosis in the Brake System. Then carry out a final check as in point 3.
NO: Continue with point 2.





2. Check the wheel speed signal

- Raise the car at the front.
- Unplug the engine control module's 70-pin connector.
- Ignition switch in-ON position.
- Connect the test lamp to pins 39 and 1 of the female connector.
- Spin the RH front wheel. The test lamp should flash.

Does the test lamp flash?
YES: Continue with point 3.
NO: Check the lead between pin 7 of the ABS engine control module and pin 39 of the Trionic engine control module for shorting and continuity. If the lead is OK, continue fault diagnosis in the Brake System.





3. Final check:

- Clear the diagnostic trouble code.
- Implementation of driving cycle: Drive the car at varying loads and engine rpm for 5 minutes.
- Evaluation of driving cycle:
- Connect an ISAT scan tool.
- Select "READ FUNCTIONS".
- Select "CAR SPEED".
- Check that the ISAT scan tool shows the same speed as the speedometer.

Is the ISAT scan tool reading incorrect?
YES: Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO: The remedial measure taken was correct.