K75 turn signals all flash above 2500 RPM

[geezergearhead]

Hi fellow gearheads,

My K75S started having problems with all turn signals flashing whenever I used the right signal button and the engine RPM is above 2.5K.  It worked correctly when using the left turn signal.   I tried switching out the flasher module from another bike that had worked correctly and it then had the problem whenever I used the left turn signal, but the right turn signal works correctly.   If I let the RPM drop to idle speed, they work correctly again until I rev up to around 2.5K and they all start flashing again.  they time/distance cancel correctly and I notice that when I first push the signal button, it flashes correctly for maybe two or three flashes before they all start flashing again.   I'm wondering if the problem could be in the instrument cluster, except that the problem switched from the right turn to the left turn when I swapped flasher modules.  Seems, IMO, that the instrument cluster wouldn't care which flasher I had in it. 

Any ideas?

[John Lang]

Strange and inexplicable behaviour is often caused by a faulty ground connection: battery negative to transmission housing; under tank; starter brushes. Check/clean these, cross fingers, test whether problem persists.

[Laitch]

Strange and inexplicable behaviour is often caused by a faulty ground connection: battery negative to transmission housing; under tank; starter brushes. Check/clean these, cross fingers, test whether problem persists.

+1 except I would add burning incense and chanting after the checking and cleaning.

[Scott_]

Are you using traditional incandescent lamps, or have any of them been replaced with LED lamps.
Is it a "hyper" super fast flash, or just that all four start flashing as if someone turned on the hazard flasher switch.

[The Mighty Gryphon]

Speaking of hazard flashers, does your bike have them? 

Just yesterday I did soome work on my K100rs that included resoldering the wires on my hazard switch.  There is some circuitry on that switch that is connected when the flashers are OFF. 

This might be a place you want to look into for your problem.

[riccas59]

My 1992 K75S is doing the same thing. Found this post while searching for answers. Still looking.

[Chaos]

any chance it has a run-n-lits kit that makes the turn signals into running lights?  It uses dual filament 1157 bulbs, it is possible for the blinker filament to sag onto the running light filament, causing all four lights to flash.  The higher revs may raise the voltage enough to cause it. Happened to an old VW bug I had many moons ago.  http://www.run-n-lites.com/products.html

[riccas59]

1992, but new to me. Just got title / registration for low mileage bike that arrived a week ago. On my way to vehicle inspection..., noticed the right flasher triggering the hazard (all flashers.) Thankfully, at inspection..., tech had me go through the lights, at idle (he missed horn and high beam check) thankfully, everything worked. Got my inspection, registration..., and put a few miles on the bike. Right flasher / hazard..., too much of an annoyance to get very far. Thanks for the suggestion. I'll include filaments and bulb type in my checklist. Luv old bugs!

[ackgs]

Any of you find an answer yet? My '91 S just began doing the same thing. Mine involves the left turn signal - At idle it usually works ok but on the road (higher RPM) it malfunctions. Hit the left signal and both sides flash like hazards sometimes I get a couple of normal flashes then the hazard thing. The bike does not have hazard flashers. No LED lamps or non stock items installed.  I have not had time to delve into it yet but am interested in what you might have tried that did or did not work. I will check the grounds and check the pins on the relay first. Will try Johnny's starter trick too.

[Laitch]

My '91 S just began doing the same thing. Mine involves the left turn signal - At idle it usually works ok but on the road (higher RPM) it malfunctions. Hit the left signal and both sides flash like hazards sometimes I get a couple of normal flashes then the hazard thing.

http://www.motobrick.com/index.php?topic=1100.0

[ackgs]

Thanks Laitch. Did do a search first but that one did not come up. Will try the starter thing after work and then check connections etc.

[ackgs]

Tried Johnny's roll the bike backwards in gear and pop the clutch to turn the starter backwards suggestion. Cleans crud off the starter brushes - who knew. Well Johnny and others evidently. Did it several times and went for a test ride worked like a champ! No more flasher confusion. The old girl is back to normal function. YES!  :riding: