Car Speed, Input Signal

FAULT DIAGNOSIS, CAR SPEED, INPUT SIGNAL FROM MAIN INSTRUMENT DISPLAY PANEL

Fault Symptom.
Slight deterioration in idling control conceivable.

Diagnostic Procedure.
1. Connect a Scan Tool.
Select "READ FUNCTIONS".
Select "CAR SPEED".
Drive the car and compare the speed on the Scan Tool display with that indicated on the speedometer.

If they coincide, proceed to step 3.
If they do not coincide or are incorrect, continue with step 2.





2. Connect a BOB.
Jack up the front of the car.
Start the engine, engage 1st gear and run it up to about 20 km/h.
Measure the voltage (AC) across pins 9 and 14.
- The voltage should be about 6.5 V and the frequency about 15 Hz.

If the voltage is correct, continue at "Procedure Before ECM Replacement". Component Tests
If the voltage is not OK or absent:
- check the lead between pin 9 of the control module and pin 2 of the speed sensor for continuity/ shorting. The speed sensor is located in the main instrument display panel.
- Check the speed sensor.

3. Drive the car on test to check whether the fault symptoms persist.

If the fault symptoms persist, continue at "Procedure Before ECM Replacement". Component Tests
If the trouble does not persist, the remedial measure taken was correct, otherwise the fault is of intermittent type.