B1705

B1705

Vehicle speed signal faulty

Fault symptoms
Speedometer in max. position, 250 km/h.

Condition
Speed information from ABS exceeds 270 km/h.

Diagnostic help
A reading of the current speed can be obtained with the diagnostic tool.
The speedometer can also be activated with the diagnostic tool.
When the speedometer is activated with the diagnostic tool, the reading obtained will not go out on the bus.

Check the wiring harness
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Diagnostic procedure

1. Checking ABS diagnostic trouble codes
- Contact the ABS.






- Read DTC from: ABS.






Are there any ABS diagnostic trouble codes?
YES
- Continue with fault diagnosis of the ABS.
NO
- Go to step 2.

2. Checking speed information from ABS
- Drive the car and read oft the speed on the diagnostic tool.






Is the value reasonable?
YES
- Go to step 5.
NO
- Go to step 3.

3. Checking speed value from ABS
- Unplug connector: H33-2.
- Remove pin 6 from the male side of the connector.






- Plug in the connector.






- Connect a test lamp to B+ and pin 6 (removed from the male connector side).






- Lift the rear of the car.






- Turn the ignition switch to ON.






- Rotate the left rear wheel.






- The test lamp should flash.






Is the function correct?
YES
- Go to step 4.
NO
- Repair or replace the lead between pin 6 of connector H33-2 and pin 23 of the ABS control module.
- Go to step 5.

4. Checking, vehicle speed signal
- Refit the pin that was removed from the connector.






- Plug in the connector.






- Unplug connector: Main instrument unit's 12-pin connector: (540).






- Connect a test lamp to B+ and MIU K12 pin 10.






- Turn the ignition switch to ON.






- Rotate the left rear wheel.






- The test lamp should flash.






Is the function correct?
YES
- Go to step 5.
NO
- Repair or replace the lead between pin 6 of connector H33-2 and pin 10 of the MIU's K12.
- Go to step 5.

5. Final check
- Clear the diagnostic trouble codes.






- Perform a functional test.






- Check that no diagnostic trouble codes recur.






Is the function correct?
YES
- The steps taken to rectify the fault were correct.
NO
- See Fault diagnosis, general, "Before changing a control module."
Before Changing A Control Module