Flickering Headlights Issue
 

Hi all,

I had a customer's 75 here today for a bi-xenon quad projector upgrade and we came across a bit of a problem. The car can't seem to handle 4 x xenon projectors, when 4 are running the outer to (factory xenons) keep flickering now and again. The xenon burners in the inner bi-xenon projector's I fitted work fine with no flickering.

Tested the bi-xenon lights on my ZT and they work perfectly fine, no flickering at all, there's definitely no fault with the headlight, burners or ballasts and I tried swapping all the bits just to be sure.

What we have noticed is that when standard headlights are fitted to the 75 (halogen projector or xenon) and the high beam is on, when I rev the engine the high beams dims down quite a bit every time the engine goes back to idle speed, and then gets brighter after about a second. Also when I increase the revs the high beam gets slightly brighter. So for some reason the voltage for the headlights keeps dropping, which would explain why the xenons keep flickering.

I've eliminated it being the battery at fault, as I tried a spare brand new battery and it didn't solve the problem. So would this be an alternator issue? Voltage across the battery is 14v and drops to 13v for a second or two after revving the engine.

The engine idles quite lumpy and isn't quite settled, not sure if that would be related.

Any input would be much appreciated :)

Cheers,
Rick

Have you any means of testing the alternator output Rick as it sounds as if that may be the problem... Not that I'm an expert...:shocked:
Cheers Ian

Had it before rick....
It is ampage from the alternator....
Especially common on cars with the 2 pin original alt...

Spot on Pete
Some of the later 120amp 2 pin alternators suffer from this :huh:
Mick

hi rick,

i think we have the same issue with your cutomer on my quad xenons. it just flickers all the time, i need to see you once you found a way to correct it. :)

Have you checked the obvious things like resistance to earth and voltage being supplied to headlights (not at battery) when it happens?

Sounds like a poor earth to me - I had lots of problems with corroded wiring on my ZT. It all looked ok but when you cut it back half the wiring had turned black.

Rick have you also checked the wiring chaffing on the chassis driver side mainly under the light ? worth a loo maybe Arctic.

Didn't have any way of testing the alternator unfortunately and didn't have the time as he had to head back home. Advised him to get his alternator checked anyways.


Cheers Pete, thought it could be alternator related, it's a mkii facelift model.

Hi Andrew,

Are the quad xenons the same as the ones I do, did you get them from Pete (Klarzy) ? :) I'll post on here what the cause is once we find it :)

Wasn't able to check anything like that unfortunately, wiring and earths looked fine but didn't cut into the wires to check them.

Yes checked all the wiring as I thought this may have been causing it but the wiring is all fine with no chaffing :)


What's had me thinking it's a alternator issue that when the bi-xenons are fitted the factory xenons on both headlights flicker perfectly in time and sync with each other, and that I would have thought could only be caused by an issue with the power going to the headlights. If the headlights had an earthing issue then I wouldn't have thought the flickering would be perfectly in sync with each other since the headlights are earthed individually.

Hi all, quick update - the alternator has been tested by an auto electrician and has shown no fault. Don't know anything about alternators or how they're tested but could there still be an issue with the alternator ?

I remember reading about issues with the regulator on the alternator? Could this be the cause?

Cheers,
Rick

If someone's tested the alternator and said it's ok, then why do you still suspect the alternator? What was the point of getting it tested if you still suspect it?
If it's easily reproducible, why not just wire the lights up direct to the battery with fresh cable as a test? That would rule out a lot of bits in the middle.