'89 K100RS Speedo quit

Speedo quit working while sitting in garage...no kidding! Rode it yesterday for first time this year, and was surprised to see this. My workshop manual doesn't even list "speedometer" in the index, so I'm asking for others' experience before checking it out myself.
Thanks jb

Ride the bike and see if the turn signals auto cancel. This will tell us if the speed sensor on the final drive is working.

roncooper said:

Ride the bike and see if the turn signals auto cancel. This will tell us if the speed sensor on the final drive is working.

Click to expand...

Thanks for the reply. Just rode the bike and the turn signals do work, but don't auto-cancel. Also noticed that the speedo instrument pod light is out (tach side is on). When the sun peeks over the mountain I'll go out and see if there's a wiring connector visible, but otherwise I have no info to guide in the diagnosis process. All guidance is appreciated.
jb

These four links should get you started

Link 1
Link 2
Link 3
Link 4

Good luck and make sure you report back!

JB,

While drneo's suggestions are very helpful, they will not correct your problem. Ron's suggestion to check the self canceling of your turn signals tells us that the problem is NOT in the instrument cluster, but rather in the signal (or to be more precise, the lack of signal) from the sensor on the final drive. That signal goes to the speedo AND to the turn signal module under the gas tank. If the turn signal module is not receiving a signal to cause the self canceling to work neither is the speedo.

Good news is you don't have to remove the speedo. Bad news is you probably need a sensor (cheaper and easier to replace).

The most common failure is a break in the wires on either side of the two pin connector, right by your coolant overflow bottle.

Also common is corrosion in the connector itself (cheapest and easiest fix).

The easiest way to test the sensor and wiring is to remove the sensor from the rear end. Then have a helper hold the tip of a soldering iron or gun (turned on) within 1/8" of the tip of the sensor. Don't touch them together. If all is working, the speedo should register somewhere around 40mph. This is caused by the 60 cycles of AC going through the iron.

If it does not register wiggle the wires near the connector to find the break. Hopefully it will be on the sensor side.

Odds are you are going to have to replace the sensor with a new or used one from any early K.

Please let us know what you find.

WOW! You guys are really on top of this issue and I appreciate greatly your advice/help.
Earlier today I located the two pin connector by the rear brake reservoir and disconnected it. Looked dry and clean inside, but after reading the links I'll take a flashlight out and look things over again more carefully.
And then I'll do the soldering iron test.
Thanks again, JB

xwingnut said:

WOW! You guys are really on top of this issue and I appreciate greatly your advice/help.
Earlier today I located the two pin connector by the rear brake reservoir and disconnected it. Looked dry and clean inside, but after reading the links I'll take a flashlight out and look things over again more carefully.
And then I'll do the soldering iron test.
Thanks again, JB

Click to expand...

My 86 K75c speedo was dead on the day of delivery and replaced with one from another bike. It intermittently quit working for the first 20,000 miles...

Only problem I ever really had with that bike in 13-yrs and 80,000 miles

xwingnut said:

WOW! You guys are really on top of this issue and I appreciate greatly your advice/help.
Earlier today I located the two pin connector by the rear brake reservoir and disconnected it. Looked dry and clean inside, but after reading the links I'll take a flashlight out and look things over again more carefully.
And then I'll do the soldering iron test.
Thanks again, JB

Click to expand...

JB,

Be sure you have the CORRECT two pin connector (there are a couple of them in that area). Just trace the wire back to the sender.

Update 3/23/17
Removed the speedo sender unit....looks clean and good. Rechecked the connector by the brake reservoir and confirmed it's dry and without corrosion. Turned on the bike's key switch and held a soldering iron 1/8" to the sender....nothing; did the same with a hobby heat gun...nothing.
I did NOT run the engine, only turned on the key switch.

Thanks again for your help!
JB

Getting worse....
I rode the bike yesterday, but today it won't run...it started up instantly (as usual), but ran about 3 seconds and died....will turn over freely but won't fire again (about 1/2 tank of gas on board). Choke on...off...throttle off...throttle applied....spins over, but no fire.
The tach gauge seems to work still, but the speedo and fuel gauges are dead.

This isn't the end of the world, but it's pretty disappointing.

JB

JB,

It sounds like when you were messing with the speedo sensor connector that you jostled the fuel tank connector. That connector and the wires that go through the sender plate on the bottom of the tank are also known trouble areas. Bad connection, corroded connector, bad continuity through sender plate.

First thing, check all your fuses. Then open the gas cap. Put your ear to the opening and turn key (and kill switch) to run. Hit the starter button and release. You should hear the fuel pump run for about a second after you release the button. If not, clip a volt meter to the pump contacts (you need to remove the gas cap assembly) and try again. If no voltage, check for ground continuity between the larger terminal on the pump and the ground connection bolted to the left side of the transmission right above the shift lever pivot.

The fact that the fuel guage doesn't work suggests that the ground is not getting to the fuel sender and pump. Check the ground on the bike side of the connector. If it's good, check ground continuity from tank side of connector to the large terminal on the pump.

https://forums.bmwmoa.org/showthread.php?72833-Fuel-Tank-Pump-Level-Sensor-Wiring-All-Early-Kbikes

Thanks again Lee...I ran out of time yesterday, and have a few hours this morning to mess about with bikes, so will take a look. The onset of the no-start issue is so sudden, it makes sense that something like a loose connection/wire could be the culprit. I have almost no history on the bike, having bought it one year ago. My first tasks were to change out engine/transmission fluids (which were pretty old) and replace the tires that were 10 years old, then a new battery. A few months ago, the ABS lights stay on and the test says the control module is at fault (happened about 6 months after changing out the battery). Practically no one within 100 miles of me will work on bikes this old, so I'm slowly getting educated it seems.
And with a '09 R1200RT and a '15 Can Am Spyder F3-S I don't ride the brick often.

JB

JB,

After you get the bike running again we can work on the ABS. Most times, just CORRECTLY reseting the ABS takes care of it. If not, I have several good ABS computers.

Thanks Lee!
More later,
jb

I'm happy to report that the engine is running again and the speedo is working again.
After checking the fuses and found all good, then in preparing to remove the fuel tank, I went to disconnect the fuel tank connector and found it not fully seated, so pushed it back in securely and reconnected the battery neg. lead and VOILA! the bike started up instantly, and I gave a big sigh of relief! No doubt that I had checked it for signs of corrosion and simply didn't push it home securely.
As for the speedo, I have no explanation why it quit and none for why it started working again.

Now, as for the ABS module, the connector pins looked clean and in good shape. I noticed a piece of tape with a name on it (which I couldn't read), so it's very possible that the ABS module has been worked on or a used one installed sometime in the past. It worked fine when I bought the bike, but now both ABS lights flash simultaneously all the time. Although I believe that I reset the unit per instructions in the forum, I'll recheck that just for drill.
Here's the big question: Is it true that, with the ABS lights flashing, it's possible to lose ALL braking without warning? Or will the brakes continue to function, just without ABS? Important, since one is life/death potential, the other is not.

Again, I'm grateful for the support and advice given by all of you!
jb

[QUOTE=xwingnut;
Here's the big question: Is it true that, with the ABS lights flashing, it's possible to lose ALL braking without warning? Or will the brakes continue to function, just without ABS? Important, since one is life/death potential, the other is not.


The brakes will continue to work on the bike, but with no ABS. I have read somewhere that some later bikes lose some or all braking.

JB,

To reset ABS (in this order):

SECURELY ground center pin of diagnostic plug. Suggest using ground terminal on battery (if ground is poor or lost, even for a split second during the process, reset will fail).

Push and hold ABS switch on dash.

Turn key and kill switch to run position.

Count 30 flashes.

Turn key off.

Release ABS switch (do not release until AFTER turning key off).

Remove grounding wire from diagnostic plug.

Test ride. If successful, ABS light should go out within 100yds and bulb check light should go out after both brakes have been applied.

JB,

The fact that your speedometer now works, with only the manipulation of the plug and wires near the plug, suggests that the problem is either corrosion in the plug or damaged wires near the plug (where wiggling them will make it connect or open). The soldering iron test combined with wiggling the wires should help confirm this if it returns.

Clean the connector pins with a good contact cleaner.

Gentlemen: It is with great pleasure I can announce that ALL functions are normal...the engine starts; the speedo reads MPH; and the flashing ABS lights are gone!!!
I'm truly indebted to you all for support and help in resolving these issues. Hope I can play it forward for someone. Now to get back to riding more!
JB

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