Problem: one rear light is brighter than the other - help!

A

a11y

Veteran
 Central Scotland
A mate pointed out to me that my driver (right) side rear light is significantly brighter than the passenger (left) side. I checked it tonight and there is a significant difference :(

It's affecting both rear tail-light bulbs on each side, i.e. the full circle. The duller side (the passenger side) also seems to be "pulsing" too, by that I mean it flickers ever so slightly becoming even duller.

Any suggestions as to what the cause of this problem is? Lights are the standard BMW units. I'm not using the "full circle" brake light mod either.

Cheers
Ally

(2004 pre-facelift 3.0i SE if that makes any difference)
 
Cheers for quick replies.

I've checked the bulbs - connections appear to be OK. It's strange that it affects both sidelight bulbs on the one side, so I'd ruled out a bad connection straight away... (but I could be wrong in my assumption).

Earthing was my next thing, but to be totally honest I'm not sure where to start investigating for the earth connection around the lamp unit. Can anyone give me pointers/advice as to what I should do to check the earth? Where's the earthing point for starters?

Sorry, bit of a beginner when it comes to this.
 
I'm not going out in the dark looking...

I would disconnect the harness and reconnect as that would be an obvious weak point.
Next I'd identify the earth from the light to car body and run a temp parallel one to a good earth. IIRC that will be the brown lead.
If no success then I'd be looking at an internal fault in the light unit, assuming all the other lights work correctly.
 
Thanks cj, I'll give it a try tomorrow night. And there was me thinking I left all my electric problems behind when I sold my Clio :(
 
I have the same issue and tomorrow its going to the dealer :) Turned out to be one of the connectors or whatevwe it is called located on one of the wires in proximimity of the bulb. :(
 
czechT698, thanks for your reply. I'll look at that as a possible cause. I've still not had time to check it yet...
 
a11y, yup, just pop the trunk and open the light cluster... try moving around some bulbs to see if they are the source (unlikely but possible), then visually inspect all the connectors and wireings and you should see the problem, my smells like BBQ. :)
 
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