R100 instrument cluster plug

Discussion in 'Airheads' started by Big John Sny, Nov 30, 2011.

  1. Big John Sny

    Big John Sny Been here awhile

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    Anyone else here have any issues with the plug that goes to the cluster. I get lights that dont work when it is cold outside. I have cleaned all of the terminals and it gets better, but on cold mornings I am not making good contact after a couple of weeks or so. I have tried putting dielectric grease on the contacts to try and keep them corrosion free. I don't much care about the gen light since I have a voltmeter, but I don't like riding without an oil warning light I can trust.
    #1
  2. PaulRS

    PaulRS Dutch fool

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    You sure it's the plug causing this problem?

    Most of these problems are hidden inside the cluster.
    Open it up and be amazed how flimsy the bulbs fit in the plastic 'print plate'. :huh
    Give that a good clean.

    Oh, and you defiantly want your gen lt to work, on lt means no charge.

    Paul.
    #2
  3. disston

    disston ShadeTreeExpert

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    I think your battery may be getting weak. If the Gen light is off the alternator is not working. The Gen light is part of the circuit. How's your bike running? Does the Batt have enough juice to start?

    There are contact cleaners that leave a dielectric residue. I think this may be better than what ever dielectric grease you use. Electronic contact cleaners are usually not at the auto parts stores but you can find them at Radio Shack or electronics supply stores. Sometimes sold under the name of TV Tuner Cleaner.

    I have fixed these type of plugs by carefully bending the contacts with a small probe, sharp pointy thing.Carefully insert sharp pointy object into space between rubber part of plug and metal female socket. Object is to only slightly deform or reform the metal so it will make contact. In severe cases I have deformed the male portion of the plug by squeezing each individual prong with a pair of pliers. I don't think this is needed on an Airhead. Just fix the harness side of the plug enough so it makes contact.

    Charlie
    #3
  4. shel-bou

    shel-bou Adventurer

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    Had the same problem with my 1986 R100.
    1. use a voltmeter to see if there is voltage at the pin in the plug which supplies non working light.
    2.If there is voltage check light and circut board with voltmeter on ohms.
    3. If no voltage see if there is voltage in wire suppling pin.
    4.If there is voltage in wire but not the pin then plug is faulty.
    5.If no voltage in wire trace back thru loom.

    On my bike the plug was faulty didn't want to buy new so I bought used slightly different colour code on wires. Used clymers manual schematic to match the wires. When buying used plug there are two different types I think change was 1979-1980. Check Max BMW fiche.
    #4
  5. boxerboy81

    boxerboy81 Stay Horizontal

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    Are we talking about the thick multi female plug that fits into the rear of the instrument shell, which the circuit board within the shell fits into?

    Only clean the plugs with electrical cleaner, avoid using a dremel and small attachment. The plugs will be clean, but might also be loose.

    The internal circuit board might be toast after these many years, so an inspection and testing as described above may be a valuable start.

    If the plug at the top of the loom (which fits into the back of the instruments) is toast, then I believe they are nla.

    I've previously read that they were made by Wurth, but not any more. A good used one is an option, but then it still needs to be spliced into the old loom.
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I believe the wiring harness plug used to be available, but not any longer. A decent used harness is the solution there. Check it out as already suggested. There are numbers on the plug for each connection and those are listed in the wiring diagram.

    The harness can be worn in the area under the steering head where it constantly flexes. It's possible some wires are shorting together. I've seen that and bad connections at the plug. But I've seen high resistance in the light board much more frequently. That's where I'd look first.
    #6
  7. Big John Sny

    Big John Sny Been here awhile

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    I cleaned the contacts in the in the plug as well as the pins. I also cleaned the contacts on the circuit board in the speedo itself, however, I did not check the resistance. That is a great suggestion. I find it weird that it only happens when the speedometer is cold. Acording to my voltmeter I am putting out nearly 14 volts over 3000 RPM. After the last time of cleaning every contact, it now only doesn't show the oil and neutral light when the temp gets to the mid thirties. The lights were fine again by the time the temp got up to the low 40's. I find that really odd.

    Thanks for all of the suggestions.
    #7
  8. disston

    disston ShadeTreeExpert

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    I thought you might like to have somebody agree with you. Yes it seems odd to me too that you get this problem only when it is cold.

    Maybe it's not a problem but an idiosyncrasy.

    Charlie
    #8
  9. Big John Sny

    Big John Sny Been here awhile

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    Ha, is that like saying that my beemer is not unreliable; it just has character?

    Also I can push the plug to one side or the other and they come back on while I am pushing on it.
    #9
  10. shel-bou

    shel-bou Adventurer

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    I should mention the mylar printed board inside the instrument housing is troublesome. The sockets where the lights plug into wear out. When the instrument housing is apart check the contacts for the lights with ohm meter or you might be able to plug in the cluster plug and wiggle the lights. I think the printed board is still available or try e-bay [german]. Used electrical stuff is risky check vendors rating. I call it a printed board but it's just a mylar sheet.
    #10
  11. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Not really a mylar sheet - but copper circuit traces sandwiched between two layers of plastic (mylar?). The problem is that the pins (that contact the big rectangular harness plug) are only staked to the traces. After thirty or forty years enough corrosion builds up in there that electricity isn't flowing from the pin to the copper trace.

    I wish it was possible to re-create that mylar sheet. I've got ideas how to fix these things, but a replacement circuit would be ideal.

    Pushing on the harness plug to enable the lights, could be the plug or those pins. Are you sure the female connections are tight?
    #11
  12. Big John Sny

    Big John Sny Been here awhile

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    I tried pinching them down just a bit to try and make sure the plug was tight on the pins. If the resistance is high between the pin and the copper ribbon, maybe I could try to solder the connection, or quit being a tight wad and replace it.
    #12
  13. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Have you looked at the price of those light boards recently? I wouldn't call you a tight wad for trying to fix it. On top of that, some of the early ones are NLA.

    The first ones I soldered came out pretty ugly, but they worked. The trickiest part is getting solder to flow when there's corrosion, but you've got to solder because there's corrosion. So it's gotta get cleaned first as good as possible, and then not heat it too much or the pins loosen in the plastic and all the mylar melts. :lol3
    #13
  14. Big John Sny

    Big John Sny Been here awhile

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    I haven't looked at prices. What is the going rate? I am guessing this is no longer available from BMW or just crazy priced from them?
    #14
  15. disston

    disston ShadeTreeExpert

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    Here's the page from realoem.com that shows the part. It's NLA

    http://realoem.com/bmw/showparts.do?model=0291&mospid=51884&btnr=62_0222&hg=62&fg=11&hl=26

    You can try to repair it yourself or have somebody with more experience repair it for you. If you don't have much experience with electronics type repairs then sending it out may save much grief in the long run. If ruined then somebody else may not be able to save it.

    The guy to send it to is the other guy on this thread. If you haven't noticed the Tag line on WireSpokes posts say he does instrument repairs. I've heard he's pretty good but I have no personal experience because I have been able to do all my own, so far.

    If you search the site you should be able to find some pictures and other threads about peoples repairs. There's a way to use Google to do this. That's better than the in house search engine.

    I'm personally not convinced that the problem is in the board yet. You say that pushing on the external rubber plug, to the side,makes everything work? So it's still possible that connections between the the pins and the sockets of the rubber plug are the problem? Of course pushing the rubber plug also pushes the contacts inside the instrument housing. I'm just not convinced yet but others seem to say that chances are the problem is just the board.

    Charlie
    #15
  16. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I agree - it's most likely, from the evidence presented, that it's the plug. However, don't discount the light board pins. Frankly, I think it's easier to do a resistance check on the pins than to figure out if current is making it through the plug into the light board. It's also not difficult to use a bright light and a magnifier to check out the connections in the plug. Any that look large can be carefully tightened up. But do be gentle - they can break, and then you're screwed!
    #16
  17. mattsz

    mattsz moto-gurdyist

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    My first post to ADV!

    About my first BMW, a '75 R60/6!

    Which is my first bike ever!

    Wirespokes mentioned soldering pins to the printed circuit mylar - I have recently done this with good results. I had two non-working instrument lights - brake warning light and high beam light.

    Now I don't know what to think about that brake warning light, since all my research says that it's to warn about low brake fluid level, and I don't have hydraulic brakes. But I do have a high beam, and I thought it might be nice to have *that* indicator light working. I got out the multimeter, and did lots of poking around (I didn't check any resistances, I just used the continuity tester) - I discovered that on each of those two lights, the positive pin had no electrical contact with the conductor on the mylar. So I soldered the high beam one, and now it works perfectly!

    I didn't bother with the brake light pin, since I don't know that it would ever light up anyway. Can anyone tell me about this light on this bike?
    #17
  18. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Welcome to the forum! And to riding!:evil

    You've got an adventure ahead of you!

    Well done getting the high beam indicator working.

    As for the brake light - you're right. No point messing with that one since there's no hydraulic fluid to concern you.
    #18
  19. Horsehockey

    Horsehockey A GPS? Huh?

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    Unplug the plug. Examine the female holes on the plug. They're numbered. #12 in the upper right corner is the ground for your idiot lights on the dash. As Disston has suggested above, pinch #12 just enough to deform it to ensure a tight connection to the pin. Reinsert and test.
    #19
  20. boxerboy81

    boxerboy81 Stay Horizontal

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    My R100RS hasn't shown the instrument back lights, neutral or high beam light for a while either. The indicators, oil and gen still work.
    #20