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P0501

P0501

Vehicle speed signal

Fault symptoms

CHECK ENGINE lamp (MIL) on. SHIFT UP lamp not working. Fuel shut-off in all gears. ABS warning lamp may be on.

Conditions

P0501


• Engine speed > 2600 rpm



• No speed signal for 5 seconds.



• High engine load.


Diagnostic help

A vehicle speed signal can be obtained with 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.


Check the wiring

Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.

Diagnostic procedure

1. Check the ABS diagnostic trouble codes




- Connect the ISAT Scan Tool.

- Turn the ignition switch to the ON position.

- Select "ABS M96".

- Obtain readings of the diagnostic trouble codes, if any.


Diagnostic trouble codes for the right-hand front wheel sensor are B1376 and B1377.

Does the ISAT scan tool show diagnostic trouble code B1376 or B1377?

yes

Continue fault diagnosis as described in ”Brakes" . Then carry out a final check according to point 3.


no

Continue with point 2.


2. Check the wheel speed signal



- Jack up the front end of the car.

- Unplug the Motronic control module connector.

- Turn the ignition switch to the ON position.

- Connect the test lamp to the female connector, between:

- Spin the right-hand front wheel.


The test lamp should flash.

Test lamp flashing?

yes

Continue with point 3.


no

Check the lead between pin 26 of the ABS control module and pin 42 of the Motronic control module for continuity and shorting. Repair or replace the lead if necessary. If the lead is OK, continue fault diagnosis as described in ”Brakes" .


3. Final check



- Clear the diagnostic trouble code.

- Implementation of driving cycle:

- Evaluation of driving cycle:


The ISAT scan tool should show the same speed as that indicated by the speedometer.

Does the ISAT scan tool show a different speed?

yes

Continue as described in .


no

The steps taken to rectify the fault were correct.