Wednesday, July 10, 2013

Sorting out a problem

k75s hdr

The speedometer on my ‘94 BMW K75S has been acting up – dropping to zero and staying there when I hit a bump. So I turned to the BMW MOA online Forum for answers:

Me: The speedometer on my '94 k75S is malfunctioning. If I hit a bump, the speedo needle drops to zero and stops registering speed or odometer mileage until I hit another bump. The tach remains unaffected. Does this sound like anything I can fix, or is it a case for a BMW certified tech?

Any diagnostic ideas?

Ron in Texas who rides a K75RT: Do the turn signals self cancel when the speedo is inop? If so, the final drive sensor and the connector near the rear brake resevoir are good. If not, the connector near the res. is probably poor. Both times my speedo quit, it was a dirty connector.

If this doesn't fix it then check the connector that goes into the instrument pod.

Doug in British Columbia who rides a K100RS: A tip I got from this forum when the speedometer intermittently quit working on my 91 K100RS was to "remove and replace each of the fuses several times." To this day have no idea why that worked, but it has for several thousand miles. Even the mechanically challenged (like me) are capable of trying this trick, along with the previous one, before we start handing over the bucks. May be that a questionable contact with a fuse is moved by bumps in the road to cause your speedo to quit (or again start) working. 

Let us know how this works out.

Me: I removed and replaced all fuses, then went for a ride on a bumpy road.

I hit a bump less than a mile from home and the speedo dropped to zero, then revived briefly, then crapped out again.

I rode for a couple of miles with the right turn signal on and the needle on zero and the signal never canceled itself. On the return trip, the speedo revived and another check of the turn signal cancelling showed it was working properly.


It appears the problem is at the rear end of the cable.

Not being a mechanic and not even sure what I'm looking at when I examine that part of the bike, is this something I can disconnect, clean and reconnect myself or is it beyond my meager abilities?

(I'd be grateful if someone could provide a photo of the connection in question.)

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