VOLVO
GDM-0002 - Headlamp range adjustment signal. Faulty signal
System
Gas Distribution Module (GDM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS40 (1996–2004), V40 (1996–2004)
Show models by year and engine (2)
What does this fault code mean?
The control module registers that the headlamp level setting signal stays outside its measuring range for a longer period. This occurs when a wrong spare light switch panel, one with a thumb wheel for manual adjustment, has been fitted, or when the signal wire to the adjustment motors is shorted to earth or supply voltage. The headlamps are set to their lowest position.
Possible causes
- A thumb wheel for manual headlamp adjustment is fitted
- Short circuit to earth in the signal wire to the headlamp adjustment motors
- Short circuit to supply voltage in the signal wire to the headlamp adjustment motors
What you can do
- 1Check whether the light switch panel has a thumb wheel for manual headlamp level adjustment. A car with xenon lamps should not have one
- 2Have a workshop fit a light switch panel without a thumb wheel if the wrong spare part was fitted
- 3Use a multimeter to check that the signal wire to the adjustment motors is not shorted to earth or supply voltage
- 4After the repair, check that the fault code does not return
Symptoms you may notice1
- The headlamp adjustment motor does not work
What the fault can affect1
- The headlamps are set to their lowest position
General guidance for car owners. Diagnosis on the car can point to a different cause.