Tail lights dimming when indicators on

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ost8900
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Tail lights dimming when indicators on

Post by ost8900 » Sun May 24, 2015 10:11 pm

I've just had the MOT fail due to the O/S Tail light dimming slightly when the indicator comes on, I spent about 5 hours looking at it today, couldn't seem to fix it. I've attached another grounding point to the O/S bulb holder, but that makes little, if no difference. I noticed that when there is no ground connected whatsoever, the O/S tail light flashes as if it were an indicator.
New battery less than 6 months ago, alternator also refurbished at the same time, so I doubt it's that.
I'm stumped on this one. Does anyone know why this would be happening?

Thanks,
K reg BX 17TD TXD on loan from boxwolf

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ken newbold
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Re: Tail lights dimming when indicators on

Post by ken newbold » Sun May 24, 2015 11:23 pm

It's the connections behind the nearside rear light cluster. Clean them up with electrical contact cleaner and if neccessary pinch the connector with pliers to tighten the grip.
They think it's all over, it is now!

ost8900
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Joined: Sun Aug 24, 2014 6:00 pm

Re: Tail lights dimming when indicators on

Post by ost8900 » Tue May 26, 2015 12:03 am

I'm starting to think the Tester is having me on, the actual dimming when the indicator comes on is so small it's almost unnoticeable, even now, at 11pm. You can barely see it from a meter away, even if you stare.
Surely there must be some sort of allowable limit for the MOT? It really doesn't pose a danger...

I've now cleaned both sides with strong contact cleaner, and used an emery board to clean the connectors on the bulb boards, still no difference.

I redid the grounding point on the O/S with a crimped earth, one of the pointy washers all of the Citroën original connections are done with, and that measures around 0.05 Ohm across the connection, allowing for the error in my meter, so I really don't think it's an earth leak. It could possibly be to do with the aftermarket alarm that's now missing, but if it is, I think it would be a pain to find the issue.
K reg BX 17TD TXD on loan from boxwolf

citronut
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Re: Tail lights dimming when indicators on

Post by citronut » Tue May 26, 2015 8:57 am

tighten the jaws up on firstly the small i believe 3 terminal plug connector at the back of each light unit,
if this does not fix it go through each of the other jaws on the main connectors ( at the light units ),

i usually pull one terminal out of its plastic holder at a time, clean and tighten/adjust the tightness of the jaws

regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special

no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)