PSA: Brittle wire insulation inside headlights

10295 Views 7 Replies 4 Participants Last post by G. P. Burdell, Oct 6, 2014

G. P. Burdell

Discussion Starter · Jul 22, 2014 (Edited)

If we keep our cars long enough, we'll all have to open up our xenon headlights to replace a bulb, diagnose a ballast or igniter failure, or retrofit projectors. Should you have to get into your car's headlights, be aware that you may have to contend with cracked wire insulation inside the headlight assembly.

I recently disassembled my car's original, defective ZKW bi-xenon headlights. (I replaced them several years ago with AL headlights.) The attached photo shows how two of the ballast plugs looked after I extracted one of the ballasts. Getting the the bi-xenon shutter plug (top) and the 9006 ballast power plug (bottom) out of the ballast was enough to cause the PVC insulation on the wires to crack and fall off. Fortunately, the igniter cable, which also plugs into the ballast, did not suffer the same problem. The insulation on the wires in the igniter cable was still flexible; it's made of something better than PVC. While it is still possible to get an entirely new igniter and cable from your local BMW dealer, I don't think you can get a replacement internal wire harness for the headlight.

These ZKW headlights were on the car for less than five years and were lit for up to an hour each day. Although I have not looked inside my current AL bi-xenon headlights, I suspect that their internal wire insulation is probably just as brittle by now, as they've been in daily use longer than the ZKWs. Other members here occasionally post about cracked insulation inside their AL headlights. I don't think the halogen headlights possess any internal wiring; someone please correct me if I'm mistaken.

In summary, the PVC insulation on the internal xenon headlight wiring doesn't hold up to repeated heat cycling. To avoid the possibility of an internal short-circuit, if you open up your headlights, handle the wires carefully, and be prepared to re-insulate or replace them if you observe any cracked insulation. In extreme cases, you may have to consider replacing the entire headlight assembly with a new one.

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Caver Dave

· #2 · Jul 23, 2014

While swapping lamps on my nieces 330ci with Adaptive housings, we treated the connectors/wires like spiderwebs... VERY gingerly. We still found evidence of the same insulation breakdown you've posted here.

Are there replacement harnesses available?

We used some cheesy "liquid tape" brush-on stuff, followed up with a wrap of 3M electrical tape, but my feeling is that it will continue to degrade and a matter of time before it *ALL* falls off!

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G. P. Burdell

Discussion Starter · #3 · Jul 23, 2014

Caver Dave said:
Are there replacement harnesses available?

We used some cheesy "liquid tape" brush-on stuff, followed up with a wrap of 3M electrical tape, but my feeling is that it will continue to degrade and a matter of time before it *ALL* falls off!

I'm not aware of any off-the-shelf replacement harnesses. Like the trunk lid wire harness, DIY installation of new wires, with better insulation, might be the only option short of a complete replacement of the headlight assembly.

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G. P. Burdell

Discussion Starter · #4 · Jul 24, 2014 (Edited)

I stand corrected. I looked through the BMW parts diagrams, and it appears that you can get BMW parts to rebuild AL bi-xenon headlights. Note that I only looked at the diagrams for a sedan.

You can get the short wire harness for the auto-leveling motor:

http://www.ecstuning.com/Search/SiteSearch/61138373573/ES165766/

You can also get the bracket for the AL ballast. This bracket provides the exterior ballast power and bi-xenon shutter electrical connections, and on the inside of the headlight, it looks like it provides the igniter and bi-xenon solenoid connections.

http://www.ecstuning.com/Search/SiteSearch/63126920165/ES172784/

And I think the high beam connector plugs right into the high beam bulb holder, so there doesn't appear to be a need to re-wire there.

Of these parts, the only one that might serve as a replacement for the ZKW headlights would be the auto-leveling motor harness. I haven't found any other ZKW internal wire harnesses in the parts catalog. It's one more reason to stick with the AL headlights when your ZKWs burn out - repair parts for the AL lights are easier to come by, for now.

Are there any other wires for the coupe adaptive headlights?

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DRE97

· #5 · Oct 6, 2014

We have Halogen Headlights and found the insulation on the wire harness internal to the headlights housing is failing. The housing is fine, seems like someone must be making a replacement wire harness. Hope someone will post with information as to who and where. Seems foolish to replace an entire headlight assembly to fix a $20 wire harness problem.

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