Headlight, electrical issues

[schrader7032]

Mark -

Holding the switch down is the way you flash the high beams. It bypasses the light relay, I believe. I would think the problem is most likely the bulb but could be the light relay. Suggest pulling the bulb and ohming out the terminals. You could also use your digital voltmeter and check voltages at the plug to the back of the bulb. The white wire running to the bulb is high beam; the yellow wire is low beam. The brown wire is ground. Measure the voltage across the white-brown and yellow-brown wires. If you have voltage, then it's the bulb. If not, then I'd consider replacing the relay. The relay is in the headlight bucket.

Here's a wiring diagram of your bike:

http://www.omnilex.com/public/bmw78/78r100wire.jpg

You might also want to look over the entire website:

http://www.omnilex.com/public/bmw78/

Lots of great brochures and infomation on the '78 models; I've found it to be intertaining and useful for my '78 R100/7.

Kurt in S.A.

[stormtrooper]

Thanks so much for the info!!!

[VBMWMO]

Hello, everyone...I am new to the forum...my name is Mark and I live in NC...I have a '78 R100/7 that I purchased from a Frenchman in DC last year...she runs like a dream, but he had not quite finished the cafe racer project...I guess I'll post one problem at a time...when I crank her up, the headlight won't burn...I have to hold the left switch down to, I assume, turn on the high beam. Does this sound like a bulb problem or a switch problem, or what? Any help at this time is very much appreciated...Mark





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