Conditions

Vehicle Speed. Input signal outside limits.





Fault symptoms
- CHECK ENGINE.
- Cruise control not working.
- Low engine torque on cars with manual gearbox.

On-Board Diagnostics

Type of diagnosis:





- Tests 1 and 2: Continuous. But interrupted when fault criteria fulfilled and does not restart until next driving cycle.

Enable criteria:
- Test 1: Engine running.
- Test 2: Engine running. Speed 50-205 km/h for longer than 10 s. Brake pedal not depressed.

Fault criteria:
- Test 1: Speed exceeding 270 km/h.
- Test 2: Speed rises more than 120 km/h or drops more than 50 km/h within 1 s.

Dependents:
- None.

System reaction to a fault:
- Cruise control is blocked. Vehicle speed (Bus from MIU) is used as a substitute value. The idling adaptation is blocked and reset.

OK report:
- 60 s has expired since start. Vehicle speed has exceeded 0 on some occasion.
Diagnostic help
Fault diagnosis concerns electrical faults in connecting leads to ABS (First it is checked if there are faults in the ABS or TC/ABS). If the car is equipped with TC/ABS the communication to the Trionic occurs through the P-bus.

For further information about fault diagnosis of the communication with TC/ABS. If TC/ABS is missing on the bus, diagnostic trouble code P1925 is generated, look up trouble code description.

Functions in the diagnostic tool related to the fault:
- Diagnostic status for the diagnosis.
- Vehicle speed (Leads from ABS, alternatively bus from TC/ABS.), unit km/h.

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

Proceed to Diagnostic Procedures Checking Diagnostic Trouble Codes In the ABS