Citroen C1 2011 headlight fault

[ZeeBag]

Hello,

My little C1 has a weird problem with the headlight the on passenger side

Drivers side headlight works fine on its own but plug the passenger side headlight in and both dipped and main beam come on both headlight bulbs but very faint on the passenger side headlight and when I turn the dipped beam on the dash has the dipped green symbol but main beam blue symbol is on but very faint even with main beam turned off.

Also if I unplug the drivers side headlight the passenger side headlight does not work at all.

Fitted new bulbs and I have checked all the earths and fuses I can find with a test light and multimeter and wiggled all the wires around it in case loose connection somewhere but fault persists.

My next step is the headlight relay but I have no idea where it is and good ol'google isn't helping.

If anyone knows where the headlight relay is or any other things I could try that would be very much appreciated.

Thanks you

[xantia_v6]

It sounds like the passenger side light has lost its earth connection. Measure the voltage on the earth pin of the passenger side light (with it plugged in and switched on).

[ZeeBag]

What voltage should I be seeing?, guessing if its under 12v the earth is faulty on the headlight?

[xantia_v6]

From the battery negative terminal to the ground at the headlight socket (or bulb if you can reach it) should be less than 0.5V. If the ground is missing (broken), you will probably see about 6V at this point.

[ZeeBag]

Thank you for the info , I will get stuck back into in when I get 5 mins after work.

[ZeeBag]

Hello,

I have checked the earth as you said and it does read 6V on the ground of the passenger side headlight. I put a wire from the common on the headlight to the neg on the battery and only dipped beam lit up so it looks like a broken earth, dipped beam still faint but getting somewhere now. I also tried the same thing on the drivers side see if that would help, wire from ground on the lamp to neg on battery and blew both fuses for the headlights, did not touch anything only the negative battery terminal so don't know what happed :/

I have swapped both fuses and the fault has gone away both headlights work as should now so I will see how this goes.

Thank you for your help very much appreciated , I may be back if this little car gremlin pops up again.

[xantia_v6]

I have not got a wiring diagram for the C1, but from your description I think it may have +12V from the fuses going to the common terminal of the bulb, with the dip switch grounding one filament or the other, this would explain why the fuse blew when you grounded the common pin.

Either way, a good result.

[ZeeBag]

That would make sense, guess next time I will check the terminals with a voltmeter before I start sticking wires into it and assuming they are the same