Speedo Problem

[mieczkow]

I'm having intermittent cut-out on my speedo - started a day or two ago. Sort of half-disassembled the fairing, looked at the wiring going up into the unit - nothing obviously loose. Cleaned the sending unit, etc. Speedo resumed working. Just came back from a little night ride - same thing - speedo falters, make a turn, maybe speedo starts up, falters again, etc. No other electrical problems. Gauge unit is clean (looks brand new) no problems with tach or any warning lights, etc.

Looked at the Haynes manual - pretty much useless about this as far as info or guidance.

I could sure use a few suggestions on how to conduct a basic diagnostic. How do I check out the sending unit, the integrity of the wiring going into the speedo, etc. I can read a wiring diagram pretty well.

The original unit was swapped out with a rebuilt from Palo Alto Speedometer in 1998. The unit looks brand new still.

Help!

Tom Mieczkowski
1987 K75S

[JohnHall]

They all do that! :laugh
Seriously though, take a look at the IBMWR site there are several possible solutions in the K-bike section.

[roy]

On my 85 it is almost always the connector on the rear of the Speedo housing. These connectors are held in with a single screw and plastic cap. Gently but firmly reseat the connectors and the problem should go away. The speedo is the bottom connections and I suspect that the wires slowly pull the connectors loose.

Good Luck

[mieczkow]

Thanks for the responses. I've checked the BMWIR site and there is good stuff on there. I'll start on this "fix" sometimes tonight.

Question: any way to get the instrument cluster out without taking off the whole front fairing?

[deilenberger]

Thanks for the responses. I've checked the BMWIR site and there is good stuff on there. I'll start on this "fix" sometimes tonight.

Question: any way to get the instrument cluster out without taking off the whole front fairing?Nope. Bit of a PITA, but once you get to doing bolts screws where it mounts to the frame - make SURE these are tight (they like to loosen up..)

Before you pull everything apart - try cleaning the sender connector on the right side frame tube - little square connector. I've had this one cause intermittents more than once on several K bikes..

[godzilla]

I just give mine a couple thumps and it comes back to life. :dunno

[redhot]

We pulled my whole unit out a couple of weeks ago and sort of looked it over, cleaned a few things, but didn't really take the insides apart - put it back on and it worked. HOWEVER - it has a mind of it's own. It won't go all the way back down to 0 and sometimes, it just doesn't want to work?? Now I have a GPS, so I really don't rely on it as much. Be careful if you take it off the bike, I've heard that it can be pretty sensative.

Good Luck!!

Tina

[mieczkow]

Well, how can I thank you for the numerous observations, advice, cautions, etc? You know, even when a Beemer gets busted somehow something good happens.

I strongly suspect the connection/oxidation villain. A lot of the visible connectors have a coat of crude, and I've already swapped out the old headlight connector and soldered in a new(er) one. I won't jump into the insides of the speedo - but I'll clean the heck out of any connectors I can identify. I did clean the sender unit, but maybe I'll pull that again and clean it up one more time.

I guess I'll be in the garage a bit over the next week or so - between the "C" bar swap and the speedo, this should keep me pretty busy. I've had the left side of the fairing off, so I'm pretty comfortable with the "fairing off" operation.

And as soon as I'm done with the handlebar swap, Tina, I'll send you an e-mail on the backbars.

Don't be surprised, all you guys, to hear from again at some point in the middle of this! With a "help" plea, more than likely.

[PGlaves]

Go to radio Shack or other electronics store. Get some spray circuit board cleaner. Spray the speedo board and use compressedair to work the cleaner down into the punch through connectors where the components are mounted to the board. Spray, then use compressed air three or four times. This usually cleans those connections nicely and provides a year or so of working speedo.

And - believe it or not - you can keep the thing clean by riding on washboard roads every now and then. The pounding and bouncing of the speedo cluster keeps those board contacts nice and fresh.

[cjack]

We pulled my whole unit out a couple of weeks ago and sort of looked it over, cleaned a few things, but didn't really take the insides apart - put it back on and it worked. HOWEVER - it has a mind of it's own. It won't go all the way back down to 0 and sometimes, it just doesn't want to work?? Now I have a GPS, so I really don't rely on it as much. Be careful if you take it off the bike, I've heard that it can be pretty sensative.

Good Luck!!

Tina

That is usually from a missing ground connection to the speedo. The three pins from the ckt board to the speedo are the most intermittant ones. Ground, signal, and plus 12. The permanent fix is to carefully wire across the connections and eliminate the problem forever. There are also some intermittant issues with the four pins from the ckt board to the amplifier strip mounted at the bottom of the speedo. Same fix. Wire across them with some fine wire like the kind used in CAT 5 etc.
There are no other permanent fixes for this problem except getting a new speedo-tach instrument pod which has the connectors fixed better to eliminate movement from vibration.

[SheRidesABeemer]

Does this work for anyone else? When I bought my K75, with 46K on it, one of the seller's parting comments was: "if the speedo stops working, just blow the horn 3 times". It made no sense to me at the time. But now, that's what I do. I'm the friendly neighborhood biker, tooting my horn. Sometimes I wave at non-existant friends at the same time. Sometimes I go months without a problem, other times, it will happen 3 times on a ride. Go figure.

[JimVonBaden1]

I used a fine emery board to clean all the pins inside the speedo/tach. It cleared up the intermittant issue on Tina's bike, but there is still another issue. Both the tach and the speedo wont go back to zero, and hang at 2500 RPM and 25 mph respectively. They move fine when the engine and speed go over those, but otherwise hang there.

I suspect the mechanical linkage, gears, pin slides etc. are gummed up. Is there a safe way to clean them? Electrical contact cleaner or similar?

Thanks,

Jim :brow

[cjack]

I used a fine emery board to clean all the pins inside the speedo/tach. It cleared up the intermittant issue on Tina's bike, but there is still another issue. Both the tach and the speedo wont go back to zero, and hang at 2500 RPM and 25 mph respectively. They move fine when the engine and speed go over those, but otherwise hang there.

I suspect the mechanical linkage, gears, pin slides etc. are gummed up. Is there a safe way to clean them? Electrical contact cleaner or similar?

Thanks,

Jim :brow

I think you have a missing ground somewhere. Since it is both meter movements, you need to look at the ground paths on the board and where the ground goes from the input pins #13 and #23. If you have a good clock and lighting, then the input pins and connector grounds are all good.

However...many times the black face of the instruments raises up off the plastic on the meters and interfers with the needle travel mechanically. You should be able to see this and also maybe see a slight marking where the needle(s) have rubbed the black adhesive face which has come loose. The fix, should this be the case, is to pop both needles off their shafts (carefully and straight up with a lever of some sort) and remove the faces from the meters by taking out the three or four small black screws. Then carefully (do not bend or tear...take your time with tension...glue releases with tension but it takes time) lift the black face off the plastic, clean both surfaces, and reglue using some great kind of contact cement. You can mount the plastic on a wooden board with toothpicks sticking up some drilled holes in the wood to be sure of the final alignment when you drop the black face down on the plastic. Reinstall the faces and the needles (they just press on...note the zero mark on the face).

[cjack]

Does this work for anyone else? When I bought my K75, with 46K on it, one of the seller's parting comments was: "if the speedo stops working, just blow the horn 3 times". It made no sense to me at the time. But now, that's what I do. I'm the friendly neighborhood biker, tooting my horn. Sometimes I wave at non-existant friends at the same time. Sometimes I go months without a problem, other times, it will happen 3 times on a ride. Go figure.

I guess it causes a drop in voltage and a slight surge when it comes back or maybe a spike. That could cause a tiny weld across the not so conducting pins on the speedo and temp fix the problem. Tapping the left side of the pod with your hand also works sometimes.
The seller was avoiding the fact that the speedo needed fixing or updating and new complete pods cost about $800 or so.