ZT Strange Sidelight problem Help!

Stephen Hutton · 28th November 2008, 20:36

Recently I had a dashlight warning that light bulb failure has occured, and when I switched off the engine it informed me that it was dipped beam passenger side.

So I purchased and fitted a new one via the usual wheel arch access, all OK! on the way back from Halfords, the warning sign appeared once more, light bulb failure, so going throught same proccess, but this time a side light failure, so having one of these spare I fitted that too. This time it has not resolved the warning light issue, it has now developed into the side light flashing on and off at a low level, along with the inner light (high beam) also on a low light?

So the passenger side has two low lights on with the drivers side on as a normal single side light?

Once I turn the headlights on full, the problem becomes intermittent and when I flick on high beam, the passenger side high beam flicks on and off all on its own!!

What have I done, or is it something more sinister?

Any advice if this has occured with anyone else out there!!

Simon · 28th November 2008, 21:00

Sounds like a classic case of the wiring harness just inside the inner wing becoming chaffed on the metal work. There are some rough/exposed welding and seams just where the wiring for the lights disappears into the bumper from the engine bay and over time this wiring can often rub through. Once shorting out on the metalwork all manner of peculiar happenings can occur with your lights.

All that is needed is to repair any broken or chaffed wires and suitably protect them from future wear and tear by way of wrapping them up in some insulation or fixing some insulation over the rough edges on the metalwork. Access is best with the front bumper removed but you can get to it from underneath the car by removing the small panels that cover the outer regions of the underside of the bumper (car up on axle stands/ramps, of course).

Hope that helps.

Stephen Hutton · 29th November 2008, 04:37

Thanks for your reply, that sounds like a mechanics knowledge test at an interview. I will have a look, let's hope that it isn't that, but then it does appear to make sense, why else would it behave in this manner!

thanks again

mach1rob · 29th November 2008, 12:16

It could be the earth, if that's chaffed, you'll get the same effect you see on rear lights when the whole unit flashes (remember mk4 Escorts??) it will find the easiest path to earth, be it through any other bulb/s.

Stephen Hutton · 1st December 2008, 15:14

Hi Mach1rob,

I think you maybe right, it seems strange that it has just developed, the dash warning states side lightbulb failure, but it is having some strange effect on the high beam once she's on.....it flashes on and off! but when the side lights are on the two left light lenses are dim, whilst my drivers side is normal.

I wondered whether I should swap bulbs, or remove the side light bulb and see if the behaviour changes?

let's play a little!

28th November 2008, 20:36	#1
Stephen Hutton Regular poster MG ZT CDTi Join Date: Dec 2006 Location: West Sussex Posts: 56 Thanks: 0 Thanked 0 Times in 0 Posts	ZT Strange Sidelight problem Help! Recently I had a dashlight warning that light bulb failure has occured, and when I switched off the engine it informed me that it was dipped beam passenger side. So I purchased and fitted a new one via the usual wheel arch access, all OK! on the way back from Halfords, the warning sign appeared once more, light bulb failure, so going throught same proccess, but this time a side light failure, so having one of these spare I fitted that too. This time it has not resolved the warning light issue, it has now developed into the side light flashing on and off at a low level, along with the inner light (high beam) also on a low light? So the passenger side has two low lights on with the drivers side on as a normal single side light? Once I turn the headlights on full, the problem becomes intermittent and when I flick on high beam, the passenger side high beam flicks on and off all on its own!! What have I done, or is it something more sinister? Any advice if this has occured with anyone else out there!! Last edited by Stephen Hutton; 28th November 2008 at 20:39.. Reason: spelling

29th November 2008, 04:37	#3
Stephen Hutton Regular poster MG ZT CDTi Join Date: Dec 2006 Location: West Sussex Posts: 56 Thanks: 0 Thanked 0 Times in 0 Posts	Wow, all because of a faulty bulb!! Thanks for your reply, that sounds like a mechanics knowledge test at an interview. I will have a look, let's hope that it isn't that, but then it does appear to make sense, why else would it behave in this manner! thanks again

1st December 2008, 15:14	#5
Stephen Hutton Regular poster MG ZT CDTi Join Date: Dec 2006 Location: West Sussex Posts: 56 Thanks: 0 Thanked 0 Times in 0 Posts	Earthed Hi Mach1rob, I think you maybe right, it seems strange that it has just developed, the dash warning states side lightbulb failure, but it is having some strange effect on the high beam once she's on.....it flashes on and off! but when the side lights are on the two left light lenses are dim, whilst my drivers side is normal. I wondered whether I should swap bulbs, or remove the side light bulb and see if the behaviour changes? let's play a little!

28th November 2008, 21:00	#2
Simon Banned - Join Date: Nov 2006 Location: - Posts: 10,318 Thanks: 0 Thanked 4 Times in 3 Posts	Sounds like a classic case of the wiring harness just inside the inner wing becoming chaffed on the metal work. There are some rough/exposed welding and seams just where the wiring for the lights disappears into the bumper from the engine bay and over time this wiring can often rub through. Once shorting out on the metalwork all manner of peculiar happenings can occur with your lights. All that is needed is to repair any broken or chaffed wires and suitably protect them from future wear and tear by way of wrapping them up in some insulation or fixing some insulation over the rough edges on the metalwork. Access is best with the front bumper removed but you can get to it from underneath the car by removing the small panels that cover the outer regions of the underside of the bumper (car up on axle stands/ramps, of course). Hope that helps.

29th November 2008, 12:16	#4
mach1rob Gets stuck in Join Date: Jan 2007 Posts: 889 Thanks: 0 Thanked 1 Time in 1 Post	It could be the earth, if that's chaffed, you'll get the same effect you see on rear lights when the whole unit flashes (remember mk4 Escorts??) it will find the easiest path to earth, be it through any other bulb/s.