[Chriss P. Bacon]

Hi all. I tried to get an answer from previous threads but can't seem to find any help. Also this site has saved me loads of cash by searching and diy thank you all.

So here is my problem. The drivers side(right hand side drive) dipped beam does not work. The other side works good. I have checked the bulb and it is fine. Fuse blown but it keeps burning out. So I have unplugged the headlight unit and fuse still burns.

I than proceeded to unplug the headlight switch and still a short occurs. Lastly I unplugged the relay. And still a short on the dipped light.

So the only place left to look at is the wiring harness for short or the ecu?

Any spitballing or ideas would be appreciated.
And no I haven't plugged a diagnostic tool in the obd. I don't have access to one now.

Thanks.

 

[Charmadize]

It would be my guess that one of the wires to the headlight unit is shorting to the bodywork somewhere towards the light itself. There is no easy answer I’m afraid, you need to tracing the wiring back from the headlight units, first checking the plugs itself as they can melt which can cause the wires to touch.

 

[PlasticMac]

It would be my guess that one of the wires to the headlight unit is shorting to the bodywork somewhere towards the light itself. There is no easy answer I’m afraid, you need to tracing the wiring back from the headlight units, first checking the plugs itself as they can melt which can cause the wires to touch.

Which fuse keeps blowing?
Do both main beams work OK?
When you unplugged the light switch, do you mean the connector on the rear of the rotary switch, lower right lower dash (I'm sure you do)?
Mac.

 

[Chriss P. Bacon]

Which fuse keeps blowing?
Do both main beams work OK?
When you unplugged the light switch, do you mean the connector on the rear of the rotary switch, lower right lower dash (I'm sure you do)?
Mac.

Fuse 20 for the right side dipped beam. Yes I unplugged both plugs from light cluster and rotary switch aswell the relay. But if I unplug the relay all the lights die ( understandable).

But there is still a short on the circuit. I did try to look for a short to body following the loom. But can't seem to find a problem.

 

[PlasticMac]

Fuse 20 for the right side dipped beam. Yes I unplugged both plugs from light cluster and rotary switch aswell the relay. But if I unplug the relay all the lights die ( understandable).

But there is still a short on the circuit. I did try to look for a short to body following the loom. But can't seem to find a problem.

Does the fuse still blow, when only the relay is unplugged?
The supply from fuse 20 goes to the Light Control Module, then to the right dipped beam.
So, if the fuse blows with the LCM unplugged, the short is between fuse 20 and the LCM. If not, it's between the LCM and the right dipped beam.
Mac.

 

[Chriss P. Bacon]

Does the fuse still blow, when only the relay is unplugged?
The supply from fuse 20 goes to the Light Control Module, then to the right dipped beam.
So, if the fuse blows with the LCM unplugged, the short is between fuse 20 and the LCM. If not, it's between the LCM and the right dipped beam.
Mac.

Yes my thoughts exactly. But I don't know how the light control module looks like or where is it situated on the car?

Thanks for all the help guys.

 

[PlasticMac]

Yes my thoughts exactly. But I don't know how the light control module looks like or where is it situated on the car?

Thanks for all the help guys.

Which relay are you unplugging, which you refer to above? Is it in the small relay panel below the steering wheel?
Mac.

 

[Chriss P. Bacon]

Which relay are you unplugging, which you refer to above? Is it in the small relay panel below the steering wheel?
Mac.

Yes small relay panel below steering wheel. But it is one big grayish relay. All the lights die when pulled.

 

[PlasticMac]

I think it looks like this

It has 4 wires to it, two yellow, one yellow brown and one yellow blue. I suspect that's where the fault is, in the LCM. I'd expect it to be under the lower dash trim, but only my guess
Mac

 

[David C]

4B0907357 is the Headlight Range Control module.
For the self-levelling.
It is located under the back seat.

 

[PlasticMac]

Yes small relay panel below steering wheel. But it is one big grayish relay. All the lights die when pulled.

The schematic shows the LCM is in the lower dash, 13 way relay panel. So it may well be one of the plug in relays. free the small relay panel off (couple of nuts if memory serves), then look for the two yellow wires, the yellow brown and yellow blue.
Ignore my duff post above, confused the LCM with Range Control (only on xenons).
Mac.

 

[magwych]

Do you have ordinary filament bulb lights or HID units? The latter have a self-levelling unit, that is also protected by fuse 20.

 

[PlasticMac]

The schematic shows the LCM is in the lower dash, 13 way relay panel. So it may well be one of the plug in relays. free the small relay panel off (couple of nuts if memory serves), then look for the two yellow wires, the yellow brown and yellow blue.
Ignore my duff post above, confused the LCM with Range Control (only on xenons).
Mac.

It looks like the 12 volt supply, the yellow wire, goes straight through the LCM, as it does not change colour. I think the LCM only monitors the current to feed the bulb failure on the display. The schematic shows a version with no display, and the yellow wire runs directly to the right dipped beam.
You could unplug the LCM, and link yellow to yellow on the connector, which, if the fuse does not blow, then the LCM is duff. If it still blows, remove the link to check which yellow (input to LCM or output) has a short.
Mac.

 

[Chriss P. Bacon]

Do you have ordinary filament bulb lights or HID units? The latter have a self-levelling unit, that is also protected by fuse 20.

Filament bulbs.

 

[Chriss P. Bacon]

It looks like the 12 volt supply, the yellow wire, goes straight through the LCM, as it does not change colour. I think the LCM only monitors the current to feed the bulb failure on the display. The schematic shows a version with no display, and the yellow wire runs directly to the right dipped beam.
You could unplug the LCM, and link yellow to yellow on the connector, which, if the fuse does not blow, then the LCM is duff. If it still blows, remove the link to check which yellow (input to LCM or output) has a short.
Mac.

I'll check and report back my findings.
Thanks.

 

[PlasticMac]

I'll check and report back my findings.
Thanks.

Any news?
Mac.

 

[Chriss P. Bacon]

Any news?
Mac.

Hi, I got distracted with other projects on the car. I did tie rods, sway bars , oil pickup, rocker cover gasket and many more on the car.
Hopefully this comming weekend I can focus on the lights.

The previous owner surely liked his epoxy glue. I have replaced a bunch of vacuum lines fixed with this glue not to mention the one way vacuum valves. And the more I fix the more I discover.

 

[Chriss P. Bacon]

Ok. So I poked around a little. I pulled the LCM and it still has the short on the line( no LCM connected). So that tells me that there is a short from the LCM to the lamp? Exposed wires? I followed the wires from the headlight to underneath the water bottle. And from inside switch to fusebox and from fusebox to LCM. And no expose wires.

So the only place I still need to check is where it goes from engine bay into the wipermoter tray under the plastic wiper cover.

I spend a whole day looking for the problem and now I have lost motivation.

 

[PlasticMac]

If you unplugged the lamp failure monitor, (4 wires, two of which are yellow), and the fuse still blows, then the short is between the fuse and that 4 way plug (I think 🤞).
Mac.

 

[Chriss P. Bacon]

I did found someone spliced an aftermarket phone hands-free kit in to the back of the fuse box years ago. I removed all the hands-free phone wiring. So that is the only place I can find for a possible short. But carefull inspection it seems everything is fine and not shorting.

I'll keep scratching at this and it feels it stares me right in the face.