Wheel speed, no signal

Symptom: The diagnostic trouble code for one of the other electronic systems in the car indicates that there is no speed signal.

Wheel speed, no signal

Fault symptom

The diagnostic trouble code for one of the other electronic systems in the car indicates that there is no speed signal.

Condition

Open circuit or short circuit in the electrical circuit.

Diagnostic procedure

1 Check the wiring

-	Unplug the ABS control module connector. Unplug the connector from the control module that detected the faulty wheel speed. Check the lead between the relevant control modules for continuity.

Is the lead OK?

yes

Continue with point 2.

no

Rectify the fault.

2 Check the wheel speed signal

-	Plug in the ABS control module. Jack up the car. Take a voltage reading (mV a.c.) on the relevant pin of the control module that detected the faulty wheel speed. Rotate the wheel in question by hand at about 1 revolution per second. The voltmeter reading should be >100 mV a.c.

Is the voltage reading OK?

yes

Continue fault diagnosis as described in the appropriate service manual.

no

Continue with point 3.

3 Final check

-	Check that a wheel speed signal is obtained.

•	Clear the diagnostic trouble code in the system concerned.

•	Drive the car at varying engine loads and rpm for 5 minutes.

-	Check whether the fault symptom persists.

Does the fault symptom persist?

yes

Continue with

no

The diagnostic procedure carried out was correct.