Headlight Switch Repair - Addendum II

By: Chris Bell
October 1999

I just did a headlight hi/lo switch repair using Don E's repair FAQ. After conversing with him about some discoveries, he suggested submitting this to supplement the original FAQ.

Ideally this job would be done after removing the gas tank and unplugging the entire switch from the wiring harness so it could be cleaned and repaired on a suitable table. However it can be done as Don and I did ours, with the plug end of the switch still connected somewhere underneath the gas tank. I used a magnetic bowl purchased at a tool store to hold most of the parts and laid a light colored bath towel across the tank and inside the fairing to catch anything I dropped. (WARNING: somehow secure the towel or do this in the garage or else a breeze can send all these important little pieces flying!)

My switch was dirty but that was not the only problem. When the problem originally surfaced, my low beam worked but not the high. When I started working on it Saturday everything had reversed, the high beam would work but the low beam had now failed. It turns out one of the solder contact "blobs" in the switch broke off and was rattling around inside the switch at first allowing the low beam to work, and later the high beam only.

After cleaning, I was able to attach a new "blob" of solder in place of the old one so the light is functioning fine now. I went to the BMW shop and ordered a replacement switch for $69 which will ensure that my repair will last FOREVER. (Law of Spare Parts - if you have replacement parts handy, you will never need them).

Here are some additions to President Eilenberger's repair instructions:

  1. For cleaning, the switch can easily be taken apart further than Don explained in the FAQ. Once the switch is disassembled as far as described, the hinge pin that holds the hi/lo rocker can easily be pushed out with a very small screwdriver or nail. The button part and the *many* springs, pins and contact plates in it can then be fully removed from the switch "frame" that still has all the wires soldered to it. This allows full access for cleaning all the little parts and contacts. Separate the rocker button from the frame slowly so you can identify where all the parts go during re-assembly. (It is possible to hold all the parts in place with your fingers during the separation.)
  2. The detent "ball-bearings" that can be lubed with a toothpick and grease are in fact spring loaded pins similar to the "funny brass" thingie that goes in the horn button. They can be cleaned and lubed after disassembly.
  3. Access to the screw that holds the horn button in place is buried deep in the back of the whole switch assembly. You can get a straighter shot at that screw with your screwdriver if you depress and hold the horn button while undoing and replacing the screw.
  4. The brass thingie that causes the horn to operate continuously if installed improperly: I would describe it as a pin with a collar located not quite in the middle. The shorter end of the pin goes into the spring that goes into the hole on the back of the horn button. The longer end of the pin goes into the "guts" of the switch.
As I said, after complete disassembly, I was able to heat the connection that had crumbled in my switch with a soldering iron and reconstruct the failed contact. When finished, I cleaned everything thoroughly with contact cleaner and re-assembled the switch. Before I installed it, I doused the insides and back of the whole thing pretty good with an aerosol silicone spray that will act as a lube and protect the contacts from corrosion too.

Good Luck!