Left Hand Low Beam Fault (Halogen)

[HWR]

Hi Everyone,

I'd appreciate some ideas on a persistent problem my X5 is having.
It's a 2005 3.0D Right Hand Drive.

The Left headlight is continuously failing, the vehicle is fitted with Halogen globes as standard.

A few months after purchasing the vehicle the LH Low Beam globe failed. I replaced the globe with another Halogen but the replacement blew about 4 months later.

Unsatisfied with the light out put when the second globe failed I decided to install Xenon HID kits to the lights. This was about 12 months ago)

Subsequently I have had 3 Ballasts fail in the LH Low Beam, the last ballast was connected to battery power via a relay that was triggered from the factory headlight wiring.

After the third ballast failed a few months ago I went back to Halogen globes in the Low Beam lights out of frustration. The globes that I installed into the Low Beams were both New.

The LH Low Beam globe has failed again today.

This makes a total of 3 Halogen Globes and 3 HID Ballasts in the LH Low Beam that have all failed in under 2 years.

The RH Low Beam and Both High Beam lights have been working perfectly with no problems (the high beam still have the HID kits that were installed when I first did the upgrade 12 months ago).

Out of interest, the vehicles battery was replaced about 4 months ago and the alternator output is correct.



There is clearly a problem in the LH Low Beam somewhere but I'm at a loss as to what and where the fault could be.

Has anyone had a similar problem and what did it turn out to be?

Any assistance would be greatly appreciated.

[TerminatorX5]

initially i would have suspected the output from the MOSFET in the LCM - but you said that the ballasts were fed directly from the battery and controlled via a relay, which isolated the MOSFET from the ballast.

the only common thing would be the location - there could be something in the physical environment at the LH light housing that may have caused a short or something, even though, it is still less likely with a totally different setup of HID...

sorry mate, can't help much...

[HWR]

Thanks TerminatorX5.

Hence putting the call out on here, this glitch is doing my head in.
I've got plenty of experience with Automotive work and electrical and data signaling work in general but this one is beating me.

Every time I think I have it worked out there will be something that doesn't add up.

It's like a jigsaw puzzle with an extra piece.......

[ants_oz]

The symptom makes it appear to be dirty power. Spikes causing the failure. But the relay cleans that power circuit to the ballast.

Only thing I can think of - where did you source the power for the ballast relay? I know you said battery, but was it your own wiring or did you pickup a master feed somewhere else?

Other thing that is a vague kind of possibility. Battery failed and was replaced. Why did the battery fail? I know you said the alternator is putting out a good charge, but how do you know it's a stable charge and not spiking? Rhetoric question really, because it's difficult to monitor it sufficiently to analyse. And if it's outputting a variable voltage (spiking), why isn;t it frying other things?

I know, asked and answered my own questions, but I feel that sometimes these kind of brain dump discussions can help the OP work towards a solution.

Good luck with it bloke.