Multiple light system faults displaying on dashboard

My 2007 1.6 5spd manual developed an issue where the dashboard "service fault" display indicated that the left rear indicator light was not working (but visual inspection showed it was working just fine) ,a short time later the display then extended to included information that the tail light and the stoplight were also malfunctioning , but both were working OK . I ignored this for a time ,then the indicator did stop working, but the bulb was fine . I traced the problem to a bad earth connection in the multi pin plug that connects to the left rear light unit . It was clearly not substantial enough to handle the current being applied and had overheated and corroded . I fixed the problem by making a new earth lead that bypassed the multi pin pug ,soldering that directly to the metal "frame" of the tail light assembly . Within a month of fixing the LH rear unit, the RH rear unit did exactly the same thing (for the same reason) and was fixed in the exact same way . This leads me to suspect that there must be other owners who have experienced the same problem as it appears to me to be due to Citroen using earth wire of insufficient capacity , or at the very least an inadequate design of multi pin plug.
Hope this helps somebody!

Thanks for the tip classic61. That is some very useful information.

Its a 2007 model, can you find the RPO/ORGA number for the car, its easy, have a look at this post:
Citroen C3 Birthday calculator

From this it will be possible to see if your wiring was modified in later years.

Sorry to drag this up again but this has just happened to me. Indicator not working, have traced it to the blown earth connector. Any advice on creating a new earth lead? Not quite sure how to do it.
Cheers

diytryer wrote:Sorry to drag this up again but this has just happened to me. Indicator not working, have traced it to the blown earth connector. Any advice on creating a new earth lead? Not quite sure how to do it.

Cut the earth wire at a convenient point, strip each cut end , join them together and crimp on a bullet connector, then find a new bit of wire and crimp a bullet on one end of that. Join the two butts together.

On the other end of your new wire fit a crimp ring and find (or make) a new clean point on some metal bodywork as your new earth. Either utilise an existing bolt and hole or make a new hole and fit a self tapping screw after cleaning up the paint work.

Basically you are cutting into the existing earth cable and 'teeing' off to a new point on the body (earth).

You can find pictures of the crimp ring and crimp bullets in this topic: How to make successful crimp connections for loom repairs.

If you don't have some spare cable to hand, you can find some suitable cable here on ebay.

Thanks a lot for that, it's really helpful! Going to try it tomorrow.

let me just check though, when you say cut the earth wire and then join the two ends together, does this mean that I can't just bypass the multipin connector? i.e. I could just cut the earth wire before it reaches the multipin connector, attach an extra piece of wire and earth that off somewhere with a ring? I'd have thought that earthing the wire on the metal body would mean that it doesn't have to be connected to the multipin connector, or is that totally wrong?

but thanks again for the help, failing further advice I think I'll stick to exactly as you've said it just in case

diytryer wrote: I'd have thought that earthing the wire on the metal body would mean that it doesn't have to be connected to the multipin connector, or is that totally wrong?

You are correct. You don't need both earths, its a 'belt and braces' attitude and doesn't make too much of a change to the wiring which could give some unexpected results.


If you get the chance to take some pictures along the way, they would be very welcome here to help others in a similar situation as yourself

Thanks for that.

Have uploaded some photos to show the precise problem, which may help someone else with their diagnostics.

Am I right to say that you're suggesting I can simply cut the earth wire before it enters the multipin connector, extend it and earth it somewhere else? I'll be honest, i'm looking for a bit of a quick fix here with my MOT next week...

diytryer wrote:Have uploaded some photos to show the precise problem, which may help someone else with their diagnostics.

Thanks. They will also help with your diagnostics too

Take a good look at the parts arrowed, I can see burned and melted bits.


This is why you are getting the error. Melted and burned electrical parts are due to a high resistance causing a high current to flow, causing more heat and damage.


Just adding a new earth or supplemental earth will not fix this fault.


The plug will need replacing, the rear light cluster will need replacing and investigation on what caused this mess in the first place will need to be conducted to avoid the problem reoccurring.

diytryer wrote:I'll be honest, i'm looking for a bit of a quick fix here with my MOT next week...

No quick fix for this, the short term solution would be to tap into the rear cluster and bypass the burned connection at the plug and socket.

Hi, thanks for the reply but obviously my ignorance is showing and now I'm more confused. I know the burnt and melted bits are what's causing the problem, that's why I posted the pictures. But I apparently mistakenly thought it was a more extreme version of the problem diagnosed in the original post:
"I traced the problem to a bad earth connection in the multi pin plug that connects to the left rear light unit . It was clearly not substantial enough to handle the current being applied and had overheated and corroded ."

And i was going to try the solution:
"I fixed the problem by making a new earth lead that bypassed the multi pin pug ,soldering that directly to the metal "frame" of the tail light assembly ."

Is that totally wrong? Can't I just bypass the multipin plug? Is my error assuming that the no. 1 socket and pin is for the earth?

Cheers

diytryer wrote:And i was going to try the solution:
"I fixed the problem by making a new earth lead that bypassed the multi pin pug ,soldering that directly to the metal "frame" of the tail light assembly ."

Is that totally wrong? Can't I just bypass the multipin plug?

Yes, bypass the multi-pin plug, you may not even need a new earth if its just a fault with the plug and socket.
This is more simple than adding a new earth.

Just jumper from inside the light cluster on a conductor that corresponds to the burned pin and connect the other end of your jumper to the wire that as the burned socket.

Sorry for the confusion, I didn't see the pictures before so I couldn't see where your fault was. But now its obvious its the actual plug/socket that is damaged rather than a faulty earth at the body.


You can find where that burned pin connects to by tracing the wiring on the lamp board, then find a good spot to connect a wire.

Is my error assuming that the no. 1 socket and pin is for the earth?

It doesn't matter what the wire does if you only jumper it over the burned plug and socket. Jumpering will work for any the wires, no matter what their function, should the need arise in the future. I don't have a diagram in front of me, so I don't know if pin one is earth or not, but that doesn't matter now.