I own a 2004 vanden plas; ....After squeezing my hands inside the assembly to change the right front directional bulb I found that there wasn't anything wrong with the existing bulb (or new bulb didn't resolve issue)...This said, after a week or so the daytime running light also stopped working on this same side....is there anything I should be looking at i.e. module, relay etc....before investigating wiring? if not, how in the heck to I trace back the wiring on this car....seems buried to deep to follow.

 

Side and Turn on each side share the same fuse
So if both are out may be the fuse or the wiring

Unlike other cars that are switched to earth to turn on the lap ours are always connected to poer and the earth is supplied by the FEM

Remove the plug and check you have power to the Orange wire
This tells you the wiring work from the fuse

Plug it back in and check you have power on the
Black/Red and Black/White wires
This tells you the globe and globe socket is working

Tune the lamp on
The black/red should read 0 volts with the side lamp on
The black/White will pulse to 0 volts as it flashes the turn lamp

If you dont get the these you may have a FEM or woring to the FEM issue
Short the Black/Red and Black/White wires to ground and see if the lamp comes on
This proves the bulb holder

To check the wiring
Check the signals at the FEM
If you get 0 volts on pins EC36-13, CR10-4, EC36-22, CR10-10 then the FEM is OK, otherwise you need a new FEM

Remove the FEM plugs and short those wires to ground this should turn on the lamps and if it doesn’t you have a wiring break. Dont bother with fining it just run a new wire

If I was to guess i'd suspect the lamp holder first but you will prove that in the first 2 checks

Cheers
34by151

 

Just to help a little, the FEM is the front electronics module, on the drivers side near the master cylinder. The signal to the turn signal starts at the column switch and goes to the instrument cluster. Then it goes to the FEM through the SCP network and then to the headlight. You might need to track it the whole way if you are not getting power at the headlamp unit. The FEM has a series of grounds that should also be looked at. Unfortunately, the days of a switch just turning on a light trough a wire directly are gone!