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Rear light wiring problem

Posted: Tue Feb 06, 2018 1:28 pm
by MOTHPRINCE78
Hello,

I was wondering if anyone could help me, I have a mk3 laser. Realised my rear tail light stopped working, so I assumed it was a bulb that had blown, after replacing the bulb. Still not working. Check the fuses they are fine, so I’m assuming it is a wiring problem, maybe some corrosion on the wire somewhere...

Is this easy to fix?

Re: Rear light wiring problem

Posted: Tue Feb 06, 2018 2:12 pm
by Peter-S
MOTHPRINCE78 wrote:Hello,

I was wondering if anyone could help me, I have a mk3 laser. Realised my rear tail light stopped working, so I assumed it was a bulb that had blown, after replacing the bulb. Still not working. Check the fuses they are fine, so I’m assuming it is a wiring problem, maybe some corrosion on the wire somewhere...

Is this easy to fix?
Make sure the replacement bulb is good, just in case. Try it in the working side.
It might just be corrosion on the contacts so trying cleaning them gently with a little wire wool. Sometimes the rear sprung contact just needs pulling forwards gently to make a firmer contact.
If this basic stuff doesn't help you need to establish if you have power at the light unit when the switch is on. Do you have any sort of test meter?

Re: Rear light wiring problem

Posted: Tue Feb 06, 2018 3:58 pm
by D366Y
I recently had the same problem and was the fuse box; I cleaned up all the contacts on the fuse box itself and was the wire coming off of fuse 1 that was the issue...

As Peter said if you have a multimeter it's very helpful in testing what points are working and aren't to help narrow it down

Re: Rear light wiring problem

Posted: Tue Feb 06, 2018 8:22 pm
by MOTHPRINCE78
Thanks guys! I’ll give the above a go :)

Re: Rear light wiring problem

Posted: Wed Feb 07, 2018 8:43 pm
by Bug
Corroded contacts in the light unit?

Cracked unit due to the two mounting screws being done up too tight? Lights earth through those screws so can cause loads of issues.

Re: Rear light wiring problem

Posted: Mon Feb 26, 2018 6:16 pm
by Bug
Bug wrote:Corroded contacts in the light unit?

Cracked unit due to the two mounting screws being done up too tight? Lights earth through those screws so can cause loads of issues.
Did you get this sorted?

Don't mind answering people's questions, but it does get a bit frustrating when you never hear what the solution turned out to be.

Re: Rear light wiring problem

Posted: Tue Feb 27, 2018 7:29 pm
by Arya2.0S
I have the exact same problem, so I was wondering if this got fixed too. I'm useless with electrics, don't know how to work a multimeter and much rather avoid doing anything in this cold if it's not going to help anyway.

Re: Rear light wiring problem

Posted: Wed Feb 28, 2018 5:07 pm
by D366Y
Arya2.0S wrote:I have the exact same problem, so I was wondering if this got fixed too. I'm useless with electrics, don't know how to work a multimeter and much rather avoid doing anything in this cold if it's not going to help anyway.
To be fair, one of the main reasons that things like this go wrong at once is usually either the wire off of fuse 1 into the loom (tiny bit of wire, should be quite clear if something is wrong with it) or the silver casing itself could be cracked and there isn't a way that I've heard of that you can multi-meter it to check if it's broken or not?

Might be worth picking one up and trying it, they're relatively inexpensive as they aren't reproduced only the original parts from cars that break, think I paid £20-30 or something??

Re: Rear light wiring problem

Posted: Thu Mar 01, 2018 4:48 pm
by 340truck
Ok 1970's, 80's and 90's Ford rear light clusters, all vehicles from Transits to Fiestas, 95% of problems are down to poor earth connections. Some like Capris earth through the mounting screws which is a particularly dumb idea imho. Some have wires bolted to some inaccessible place onb the body which corodes and fails. In any case, make a good, secure connection between the earth bar in the cluster and the car body no more than 30cm away and most problems (including other lights flashing when you put the indicators on) will simply disappear. Dont' bother messing around with fuses or multimeters until you have done this.

Re: Rear light wiring problem

Posted: Wed Mar 21, 2018 9:22 pm
by Arya2.0S
I fixed my issue today and it was a combination of a bad earth, and the zinc plated housings rusting away. As the screw that holds everything in go in they are supposed to make contact via some washers to the housings. There's two rings on each side and these are corroding away, so I'd imagine this will only be a temporary fix but it's definitely an earthing issue and mine are working again for now.