Really stuck on electrical fault in lights please help.

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
User avatar
falling-out-with-my-car
Posts: 1928
Joined: 06 Apr 2008, 15:26
Location: Northamptonshire
My Cars: Citroen C5 Aircross 8 speed Automatic, Flair Model with far to many toys and nice comfy armchair like leather seats. ha ha Ive just had a conversation with the car. setting everything up verbally
x 24

Really stuck on electrical fault in lights please help.

Post by falling-out-with-my-car »

with good intentions and whilst my son is working hard I decided to buy a little 1 litre AX for him as a run about, now I am more mecanically minded and have treated all of the rust and undersealed where necessary, changed the oil and gear oil.

a couple of days ago a fault presented its self whilst I was taking this little AX for a spin. whilst indicating left and braking at the same time the left indicator stops flashing i have cleaned and replaced the relays both relays seem to be working on the right hand side.

if I switch on the indicators all together via the warnning light switch this lights four of the rear bulb lights together these are the brake lights and the normal running lights, the front bulbs seem to be behaving themselves normally until you once again indicate left and brake at the same time.

I have cleaned the earthing points maticoulously sanded all of the bulbs and contacts but the fault still presents itself.

I am now at the point where to go any further would be beyond my own ability without a lot of help.

please has anyone any ideas or has anyone had a similar fault?

I would be very grateful for your indulgance.

Thank you in advance Nigel.
Citroen Xantia S2 1.9 TD estate 189K soon to be broken for parts Jan 2017 headlamps & radiator fan assembly already spoken for & A 1987 Citroen 2CV6 special just for fun.
New addition Citroen C5 2.0 HDi Exclusive Hatch purchased 09/12/2016 with 83K on the clock.
User avatar
spider
Posts: 3949
Joined: 05 Jan 2010, 14:28
Location: Derby.
My Cars: Soon, I hope...
x 77
Contact:

Post by spider »

It does still sound like an earthing fault OR a short in the rear lights.

Even if you clean the earthing this is no guarantee that its good, unfortunately.

Quick test:

Get a length of wire about a metre or so. Connect one end to a good earth on the body (a clean bolt or suchlike in the boot area) ensure it is a good earth point, take your time to find a decent one, don't just connect to the nearest one ;) . Connect the other end to the 'earth' on the light unit. Repeat this for both earth's (one each side etc)

If in doubt about the front, do the same for them too. Only needs to be a temporary thing just for testing. Once its fixed you can do it neatly. I used to just have lengths of wire with croc clips one end and a scotchlok the other for testing.

See if there's any improvement. I'm not familiar with the wiring on these. I can remember the 306 has two earth's on one side and one on the other. Sometimes it was necessary to do all of them. I would drill a tiny hole and solder a eyelet to a piece of wire and bolt in / rustproof etc. Hopefully will not have to be so drastic for you :)


EDIT... The next 'step' after that if its no better is to replace the rear bulbs (stop / tail) its rare but they could have a short and then borrow / replace the indicator switch then the hazard switch, in this order. I bet most of the PSA units will fit for the indicator switch.

Don't overlook the engine bay earths too, especially the body to engine / gearbox strap.
Andy.

91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
dnsey
Posts: 1538
Joined: 20 Oct 2004, 01:39
Location:
My Cars:
x 19

Post by dnsey »

I agree, it's almost certainly a poor earth.
An alternative approach is to turn on the 'faulty' lights, and connect a voltmeter between the lampholder earth contact and a known good earth. A reading any higher that a fraction of a Volt more or less confirms the diagnosis.
User avatar
mongoose100
Posts: 206
Joined: 18 Nov 2010, 08:33
Location: Wellington, New Zealand
My Cars:

Post by mongoose100 »

Have you tried running a seperate earth wire directly from the lights to the car body?

I had a 306 that did this, that seemed to be the only option I had left.

Not fitted with a trailer plug by any chance?
Regan.

2001 Citroën C5 V6
1994 Citroën Xantia 1.9TD
xmexclusive
Posts: 419
Joined: 18 Dec 2008, 22:50
Location:
My Cars:

Post by xmexclusive »

Does the AX suffer from cracked and broken wiring in the rubber concentina by the tailgate hinges? The bigger Citroens do and the resulting breaks and shorts can produce the most unusual symptoms. This fault seems to depend on how much the tailgate gets used rather than being mileaged based. Open the tailgate, flex the rubber a bit and see if faults change.

John
Xmexclusive
User avatar
falling-out-with-my-car
Posts: 1928
Joined: 06 Apr 2008, 15:26
Location: Northamptonshire
My Cars: Citroen C5 Aircross 8 speed Automatic, Flair Model with far to many toys and nice comfy armchair like leather seats. ha ha Ive just had a conversation with the car. setting everything up verbally
x 24

Post by falling-out-with-my-car »

Thanks everyone,

even though it was only 3 degrees C yesterday I stuck at it to find a solution, there were whiskers of metal shorting the pins on the back of the rear light bulb holders this seems to be caused by oxidisation of the contacts, someone in the past had pushed the bulb holders to hard into the rear light lenses collapsing some of the bulb holder galvanised metal tracking onto another section of tracking so that there was a short in both lamps, I seperated the tracking with a small screwdriver and aeraldited the stips of metal so that they didnt move again if similar pressure was put on them, these bulb holders are flimsy to say the least (cheap and nasty) a bit like the tin bucket AX car.

Thanks for all your suggestions above it is appreciated, a note for the future to anyone with a similar problem inspect the connection pins on the back of the bulb holder with a magnifiying glass and look for oxidisation between the contacts, if the contacts have been cleaned with sandpaper in the past there is also the posibility of fragments (whiskers) of metal shorting between the contacts which are difficult to see with the naked eye.

regards Nigel.
Citroen Xantia S2 1.9 TD estate 189K soon to be broken for parts Jan 2017 headlamps & radiator fan assembly already spoken for & A 1987 Citroen 2CV6 special just for fun.
New addition Citroen C5 2.0 HDi Exclusive Hatch purchased 09/12/2016 with 83K on the clock.
Post Reply