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Thread: 76 R90/6 neutral light plug

  1. #1
    Registered User plehman's Avatar
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    76 R90/6 neutral light plug

    So I pulled out the spacer between the pegs to replace the neutral light switch that was leaking and nasty. I hocked up the fresh new one and still no green neutral light. Strangely, I have seen the light recently, so I thought the light in the instrument panel actually still works, but extremely intermittent. I assumed it was the transmission switch in the bottom of the transmission housing.

    Pain to remove and replace, but it was my first winter project. But why no light?

    thanks!

  2. #2
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    Check the bulb anyway. They can get a little corroded in their socket.

  3. #3
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    If I am not mistaken, this may be one of the "inni" vs "outie" issues with these switches.

    Check this site for information:

    http://bmwmotorcycletech.info/neutralswitch.htm (Snowbum)
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

  4. #4
    Registered User lmo1131's Avatar
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    Read me -> http://www.bmwmoa.org/forum/showthre...switch-anomaly
    And Me -> http://bmwmotorcycletech.info/neutralswitch.htm

    The two switches look the same but work opposite..

    Your light goes out when in neutral and on when in all the gears...which is for a late model airhead tranny.

    The only fix..not more washers...is to swap it out for the right one.
    Check the continuity of the circuit with a lamp tester to determine if the problem is inside the instrument cluster (corrosion, broken wire, bulb, etc.); move the gear selector through all gears. Obviously if the test lamp works as anticipated the problem is in the cluster. If not... you may have the wrong switch.

    through 9/'75


    from 9/'75
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  5. #5
    Registered User plehman's Avatar
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    It's the longer post 75 switch, matching the replacement exactly. But:

    "If you forget to install this ~2mm washer the neutral lamp will NOT work correctly, no matter which switch you have installed....and you may have shifting problems." snowbum

    The existing didn't have this spacer and I didn't put one in - darn. Can that really make it not work?

  6. #6
    Administrator 20774's Avatar
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    First things first...take the wire to the switch, stick a paper clip into the connector, turn on the ignition, and touch the paper clip to the engine case. If you get a light...it's the switch. If you don't get the light, then it's something with the wiring or bulb.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  7. #7
    Registered User plehman's Avatar
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    Yeah, no light. I'll pull off the S fairing and dig into the instrument cluster (again).

    Next weekend... thanks

  8. #8
    Registered User plehman's Avatar
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    open circuit

    OK, sorry for the delay. I pulled off the engine spacer (came out much easier this time) and did two things.

    1) I checked the circuit for the light. Multimeter thinks it's a good circuit. It reads open anyway. Now, I really suck when it comes to electrics so nothing is too simple or obvious.

    2) Then I checked the switch itself, which is still in the transmission. No circuit. The old switch, which was leaking and working intermittently does show an open circuit. Question: is this switch bad? (it's in the bike, in neutral, no transmission fluid yet). I would assume, remember I don't know much, it should read open circuit (as in: multimeter showing some reading - like when you touch the two leads).

    Big reason I pulled it all apart again, other than it doesn't work, is that the excellent article by Snowbum states that you need that spacer, which I stupidly didn't see on the old switch and didn't come with the new one. I will install with the old one.

    "if you forget to install this ~2mm washer the neutral lamp will NOT work correctly, no matter which switch you have installed....and you may have shifting problems."

    What do ya think?

  9. #9
    Administrator 20774's Avatar
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    1) Check the circuit? What does that mean? The easiest way to check that circuit is to find a paperclip and stick it inside the connector that goes to the instrument pod, turn on the ignition, and touch the paperclip to the engine. Does the neutral light come on? That's an indication of a good circuit. If no light, then the circuit is not good.

    2) Is the switch bad? I'm a little confused when you wrote "it should read open circuit (as in: multimeter showing some reading - like when you touch the two leads." If you touch the two leads together in the ohm setting, the meter reading will be 0 ohms or pretty close. That is a continuous circuit or the circuit has continuity from one lead to the other...duh, the leads are touching! An open reading is when you wave the two leads in the air...the meter will show probably "1." or maybe a bunch of dashes. That's an open circuit.

    If you have the switch type shown by Lew as 9/75 with the two bent over contacts, and it is installed correctly, touching the meter leads to the two contacts, with the bike in neutral, you should read pretty close to 0 ohms, ie, a continuous circuit. It sounds like if you don't have the washer, your current tests of the switch are inconclusive.

    But, do check the circuit per 1).
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #10
    Registered User plehman's Avatar
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    OK, sorry for the bad vocabulary. I tried the paperclip and bingo! I got the green neutral light. So the light circuit is good.

    Now please tell me again about the switch. I'm very sure I have the correct switch per Lew. It matches the "bad" one that was in there. Duncan of Duncan's Beemers sold it to me (he's knows the bike '76 R90/6) so it should be the longer one. Is there a test of the switch? or should I just reinstall with the spacer?

    thanks a lot.

  11. #11
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    Just so it's clear, the older switch actually made contact with ground inside the transmission. The newer switch simply closes a circuit inside the switch which then connects one of the contacts to ground. Do you have the later switch? You tested the bulb side of the circuit which connects to one of the blades of the switch. Another wire connects to the other blade and that wire goes to frame ground. Try checking for continuity from that connector to the engine...do you read 0-ish ohms? If so, then that part of the wiring is good, too.

    To test the later switch, in one condition it reads open...ie, no continuity between the two blades. If the other position, it would read continuous between the two blades. You can switch between the two conditions by pushing on the rounded part of the switch that sticks up inside the transmission. To be honest, I don't know which way the switch goes...do it close the circuit when the rounded part is protruded from the body of the switch or when it is pushed in to the body? Possibly Snowbum makes that distinction on his website.

    But at least you can tell if the switch is "switching". If it is, then either you don't have the washer/spacer installed or you could have the wrong switch for your application.

    Did we ever get the part number that you ordered? That should tell us if you at least (hopefully!) got the right part.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  12. #12
    Registered User plehman's Avatar
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    I'll have to check on Monday for the part number and will keep working on this.
    Thanks for your help.

  13. #13
    Monza Blue 1974 R90/6
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    I'll describe the above slightly differently.

    There are two type of switches.

    If you have the right one for your year transmission, when it is in neutral, the light will illuminate on the dash. When you are in gear, no light.

    If you have the wrong switch, when you are in neutral, you won't have a light. But, surprise, when you are in gear, you will have a light! So, wrong switch becomes an "in gear switch".

    As long as the problem was with your old switch, not in the wiring, connections, or dash lamp, your new switch should give you a light. Test it out before you screw it into the transmission. Attach the wires, turn on the key and press the plunger.

    The light should come on and off as you depress and release the plunger.

    Make sure that is working right before you put the switch in the transmission.

    Now, the spacer - I didn't know that every transmission needed one. I thought some did, some didn't and some might need two. It has to do with the depth that the switch protrudes into the transmission and the distance the plunger is from the piece that depresses it. No spacer, when tightened, the switch protrudes too far into the transmission, and the plunger will always be depressed. So, use a crush washer to take up some of the thread so the switch doesn't go as far into the transmission. This is a good thing to test before you fill the transmission up with oil again. Again, I think I have seen some transmissions with two crush washers to get the switch adjusted right so the plunger can fully extend.

    If the switch was working ok (light was coming on and going off as you pressed the plunger) before you installed in the transmission and now that it is installed, it doesn't work when you shift in and out of neutral, take it out, add a spacer and try it again until you get the adjustment right so that light is on in neutral and off in gear.

    Barron

  14. #14
    Registered User plehman's Avatar
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    Success

    Great explanation - thanks Barron. It is after all, just a switch. Basics!

    So with the single spacer installed (crush washer), and some clean up of the wires, the neutral light glows a satisfying green. Snowbum was right, without the spacer it will insert too far and the light won't come on (off has the button depressed).

    Now I just have to reinstall the engine spacer, but this time I've put it in the freezer over night.

    Thanks again.

  15. #15
    Monza Blue 1974 R90/6
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    Nice. Glad to hear it was just a problem with the old switch.

    Barron

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