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Thread: 1973 R75/5 Turn Signal Lights

  1. #1

    1973 R75/5 Turn Signal Lights

    I have a R75/5 without fuses. Last weekend I had the bike out and about mid-way through, the turn signals stopped working.

    All the connections seem good and there was really nothing that happened to cause the malfunction.

    Just wondering if anyone has had this problem and can offer suggestions.


    Thanks,
    Peter

  2. #2
    Liaison 20774's Avatar
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    Welcome to the forum, Peter! The circuit is pretty simple generally speaking. Power comes from the bike to the bulbs and the grounds are right there at the lights. So, first thing is to make sure the grounds are solid and that the bulbs are OK. With both not working, it sounds like the problem might be somewhere else. The handlebar switch is what sends the power to the bulbs, so it's possible there is some corrosion going on in the switch. Those early bat-wing type switches can be problematic to open up...haven't really had the pleasure! But if you do decide to have a look-see, best to work inside a big plastic bag because small parts and springs could go flying.

    Snowbum has a non-fused /5 electrical diagram here:

    https://bmwmotorcycletech.info/Slash5Schematic.jpg

    If you look at the #4 item on the top, that is the right signal. Follow the wire through the connector to the switch. The switch seems to be getting power from the turn signal flasher, so maybe that has bit the dust.
    Kurt -- Forum Liaison ---> 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!

  3. #3
    Quote Originally Posted by 20774 View Post
    Welcome to the forum, Peter! The circuit is pretty simple generally speaking. Power comes from the bike to the bulbs and the grounds are right there at the lights. So, first thing is to make sure the grounds are solid and that the bulbs are OK. With both not working, it sounds like the problem might be somewhere else. The handlebar switch is what sends the power to the bulbs, so it's possible there is some corrosion going on in the switch. Those early bat-wing type switches can be problematic to open up...haven't really had the pleasure! But if you do decide to have a look-see, best to work inside a big plastic bag because small parts and springs could go flying.

    Snowbum has a non-fused /5 electrical diagram here:

    https://bmwmotorcycletech.info/Slash5Schematic.jpg

    If you look at the #4 item on the top, that is the right signal. Follow the wire through the connector to the switch. The switch seems to be getting power from the turn signal flasher, so maybe that has bit the dust.

    Thanks, I'll give it a try.

  4. #4
    Hi Peter, I have a /5, I had a few issues with my turn signals that turned out to be a bad flasher relay, it's in the headlight bucket as you may know. Also check the connections in there, could be a simple fix. I did use a generic flasher and it just didn't work right, I ended up getting one from EME - problem solved.

    Chuck
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  5. #5
    Quote Originally Posted by mpsaxon View Post
    I have a R75/5 without fuses. Last weekend I had the bike out and about mid-way through, the turn signals stopped working.

    All the connections seem good and there was really nothing that happened to cause the malfunction.

    Just wondering if anyone has had this problem and can offer suggestions.


    Thanks,
    Peter
    Did both sides stop flashing? If so, check the wires going to the housings (have to remove the lenses) for 12vdc (pulsing) when the signals are activated.

    Grounds can be verified by simply moving the metal housings when either side is activated. The fronts ground directly to the metal housing, through the t.s. stalks, so moving them would reveal any problems.

    Rear signals have their own separate ground wires, so if the rears are attempting to flash, then you probably have ground issues at the fronts.

  6. #6
    Quote Originally Posted by RPGR90s View Post
    Did both sides stop flashing? If so, check the wires going to the housings (have to remove the lenses) for 12vdc (pulsing) when the signals are activated.

    Grounds can be verified by simply moving the metal housings when either side is activated. The fronts ground directly to the metal housing, through the t.s. stalks, so moving them would reveal any problems.

    Rear signals have their own separate ground wires, so if the rears are attempting to flash, then you probably have ground issues at the fronts.
    All 4 stopped working. The front grounds are solid. I believe I traced the rears back to the headlamp and everything seems tight there too. Someone else mentioned replacing the flasher. I thought the lamps would still light, just not flash if the flasher didn't work. Any opinion on that?

  7. #7
    Quote Originally Posted by mpsaxon View Post
    All 4 stopped working. The front grounds are solid. I believe I traced the rears back to the headlamp and everything seems tight there too. Someone else mentioned replacing the flasher. I thought the lamps would still light, just not flash if the flasher didn't work. Any opinion on that?
    I think it depends. I believe the flasher is a mechanical one, not electronic, so it essentially is a three position (center off) switch which routes power through left or right circuit. I have had two things happen, bad flasher, no lights, and bad flasher, lights on (one side only) but not flashing. Never had all lights on, not flashing. I've got a buck that says its a dead flasher.

  8. #8
    Quote Originally Posted by FELAW View Post
    I think it depends. I believe the flasher is a mechanical one, not electronic, so it essentially is a three position (center off) switch which routes power through left or right circuit. I have had two things happen, bad flasher, no lights, and bad flasher, lights on (one side only) but not flashing. Never had all lights on, not flashing. I've got a buck that says its a dead flasher.
    The flasher worked. I used an OEM flasher and it works better than ever.

    Thanks to everyone that offered help.

  9. #9
    Registered User ebeeby's Avatar
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    Mar 2003
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    McKinney, Texas
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    681
    Thanks for the update!
    1973 R75/5

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