P0571

P0571

Brake Switch "A" Circuit

Diagnostic conditions
- Battery voltage between 10 V and 16 V
- Ignition on

Possible fault causes for vehicles up to and including model year 2004
- Open circuit in the power supply for the brake light switch
- Brake light switch faulty
- Short circuit to B+ in control line
- Short circuit to ground in control line
- Open circuit in control line
- DME control module faulty

Possible fault causes for vehicles as of model year 2005
- Fault is set in PSM control module, refer to there

Affected pin for vehicles up to and including model year 2004
DME control module connector A, pin 55
DME control module connector A, pin 56

Diagnosis/troubleshooting

NOTE:
- The diagnosis checks the clearness of the status reports given for the brake light switch. If the status "Brake actuated" or "Brake not actuated" is not clearly detected, this fault is set.
- A twin brake light switch is installed in vehicles up to and including model year 2004 which is diagnosed directly by the DME.
- Vehicles as of model year 2005, this brake light switch no longer exists and is replaced by the switch in the brake master cylinder. Evaluation is carried out in the PSM control module.