91 K100RS 4V w\ABS Radical Turn Signals

I'd be looking at the central grounding point, which is located under the tank on the center-tube of the frame. It's a threaded stud welded to the tube. Take the nut off, clean (sand) each of the ring connectors and the surface of the frame that the connectors contact. DO NOT USE GREASE on the connectors... replace all the connectors and snug up the nut.

Having lots of odd-ball electrical problems usually indicates some central point is acting up. The central ground is the most "central point" in the entire electrical system on a K bike.

Central Ground is Clean...

Don,

Thanks for chiming in. The central ground was one of the first things my friend Gilbert looked at too. He owns 2 other K Bikes and an Airhead. And has owned, sold & maintained many more. But despite his experience and my 2 cents worth we are pretty much baffled.

One other point. His electrical problems are confined to the turn signals. With the possible exception of the ABS brakes. Why other relays feel & sound like they are blinking at times is odd.

The bike starts and runs fine.

Do the later bikes have a problem with dust in the starters? On the K75s, if the starter is dirty, problems arise with the electrics.

roncooper said:

Do the later bikes have a problem with dust in the starters? On the K75s, if the starter is dirty, problems arise with the electrics.

Click to expand...

No - an entirely different circuit/starter.

One other possibility is a failed wiring harness. Not a frequent failure - but it does happen. There are a LOT of wires running in rather restricted space, and at times the harnesses have been known to short. This is difficult to troubleshoot - but wiggling the harness while the wacky-stuff(tm) is happening may give a clue, if it gets worse or better, you have a suspect area. Also check any sections of the harness that are tie-wrapped to the frame.. BMW has traditionally assigned the strongest gorilla in the plant to install these, and they are almost always way over-tight (they just need to be tight enough to keep things in position..)

Checking Wiring harness... Still Looking

Happy New Year Everyone...

My friend Gilbert has since stripped, checked and re soldered the entire front lighting wiring harness. Once while the front fairing was removed it seemed the the turn signals worked perfectly.

The next time the ignition switch was turned off and on the problems returned even with the fairing off.

He is now going to start looking at the rear lighting harness. I told him not to strip it; just disconnect it and see what happens.

I'll keep you all informed as to his progress....

When you say "stripped" - do you mean he unwound the cloth tape around the harness?

The headlight/turn-signal wiring is in the main harness (that runs up near the backbone of the frame) - to really access that harness section requires R&R of it. There are two control sub-harnesses for the left/right bar controls and depending on the model there may be some small harnesses going to the actual turnsignal housings (some do, some don't..)

Yes

Yes, he unwound all the cloth in the front of the bike and soldered all the brown grounds together and even drilled a hole and screwed another ground.

Right now he has pretty much given up...

He says that he can manually blink them using the normal switches. In other words they don't blink.

Thanks again for helping Don.

Gilbert thinks he found the problem...

My friend Gilbert has been playing with the problem relentlessly for a while now. This evening he called me and told me he thinks he knows what is causing the problem:

The turn signal canceling button is stuck in the on position. If I understand him right it's constantly canceling the signal but I guess since it's located on the pod with the starter button it may even be somewhat intermittent.

Just for the record my friend Gilbert is French and does not feel comfortable writing in a forum in English.

I will write more about this issue when next I see him in person and see this bad switch for myself.

I used to have problems with the turn signal cancelling switch, too---until I squirted some WD-40 in there---now everything's fine.

Bon chance, Gilbert!