Light module (LM) fault patterns

Impact of bus faults

If individual bus signals fail that are not stored in the fault code memory

- First, perform troubleshooting on the corresponding transmitter control unit.
- If the transmitter control unit is OK, troubleshooting must be run on the receiver control unit.

Possible fault symptom or perception on failure of the corresponding bus signal	Faulty or missing signal	Transmitter control unit
No permanent main beam, emergency function while stalk remains pressed	Steering_column_stalk_operation	SZL
Turn signal is not automatically cancelled	Steering wheel angle	SZL
Turn signal is not automatically cancelled	Steering_wheel_angle_fault	SZL
Restricted monitoring of reversing lights	Trailer_status	AHM
Flashing frequency not doubled	Trailer_indicator _fault_status	AHM
Lights permanently on	Headlamp_status	AIC
No reversing lights	Transmission_gear_status	EGS
No headlamp flasher, brake lights, turn signals at Terminal R	Terminal_R_status	CAS
Position light remains on	Key_in_ignition_status	CAS
No brake lights via ACC	Brake_light_control	DSC
No stop position for turn signals, emergency function while stalk remains pressed	Steering_column_stalk_operation	SZL
No hazard warning lights with anti-theft alarm	Antitheft_alarm_control	DWA
No alarm acknowledgement active	Alarm_acknowledgement_control	DWA

Abbreviations	Full expression
ACC	Active Cruise Control
AHM	Trailer Module
AIC	Rain sensor
CAS	Car Access System
DWA	Antitheft alarm system
DSC	Dynamic Stability Control
EGS	Electronic transmission control
SZL	Steering column switch centre