Headlamp: Testing and Inspection

WM 947801 Eliminating symptoms in passenger compartment: Checking front angle sensor for range adjustment ("Check headlight beam adjustment" displayed in instrument cluster/SY1909)

General information

Concerns/symptom

Concerns

Only vehicles with steel spring suspension (I-no. 1BA/1BH or 1BW) and Xenon lighting system (I-no. 601)/Bi-Xenon lighting system (I-no. PC3).

Symptom

- Error message "Check headlight beam adjustment" displayed in the instrument cluster and
- Fault code 0774 or 0776 entered in the left headlight control unit.

Causes and remedial action

Cause

In certain steering and driving situations (e.g. driving at speed over a bump, then braking and turning right), the angle sensor can send a signal that is implausible for the headlight control unit and results in a fault being entered.

=> This is caused by a software error in the headlight control unit.

Remedial action

Information

In the event of a complaint and if fault codes (0774 or 0776) are entered, troubleshooting must be performed using the PIWIS Tester and the "Guided Fault Finding - GFF" function.

=> Erase the fault memory in the headlight control units.

=> There is no need to replace the angle sensor or the headlight control unit at present.