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    A few electrical issues...

    Hi there, long time listener, first time caller.

    Recently got me a rallycross car. It's a '91 318is.
    It's got a few issues, and I'm trying to understand how to begin diagnosing them.

    1. Turn signals:
    The turn signals don't seem to work well. The right side bulb is dim when I have the parking lights on, and neither of the front bulbs flash with the turn signal engaged. When I hit the hazards, they do indeed work.
    Yesterday, I had off-and-on performance from both sides of the front, but after I changed bulbs neither worked for turn signals again.

    2. Parking Brake light:
    Occasionally, the parking brake light turns on without any perceptible reason. Where should I check? Is there a handbrake contact I should investigate first?

    Thanks!!

    #2
    Activate your signal switch and check for power at the bulb sockets. If nothing, your switch is bad, maybe repairable, but it's often easier to just replace it.

    Check that the parking brake handle is staying down reliably, if it is you probably need a bit of an adjustment at the switch, pretty unlikely that the switch is kaput.

    Comment


      #3
      Thanks for the reply!
      I forgot to mention - the rear turn signals all work just fine. Do you still think the switch might be the culprit?

      Comment


        #4
        I would check a few of these things

        - Grounds for the turn signal, they are grounded near the bumper area. If the grounds are old and oxidized, which im sure they are, that can contribute to a voltage drop and cause issues.
        -Replace the bulbs with new, always a good idea and I think you have done this already.
        -Shorting of wires that lead from the center console to the rear seat area (that lead to the trunk) are very common to have rubbing against metal which can cause a break in the wire insulation. I would pull the console and rear seats and inspect along the length of the wiring harness but certainly check the sensor first.
        Owner - Bavarian Restoration
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          #5
          I would consider starting with replacing all related fuses too. The fuses can still be good but corroded and oxidized leading to voltage drop from increased resistance. Once the voltage drops, they can have strange behavior.
          Owner - Bavarian Restoration
          BMW and European Electronics Repair and Restoration
          www.BavRest.com
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            #6
            Thanks for the tips.
            I am truly blanking on where the grounds might be for the turn signals. Does anyone have a picture?

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              #7
              I had issues w turn signals buying off the shelf brands. Once I put the OEM bulbs I had no issues. Also make sure the bulb is making good contact w/ the metal connection in the holder....if not bend it up so it is. I even sanded down the bottom of the bulbs in case there was any corrosion/etc keeping from making a good connection.
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                #8
                IIRC, the grounds are collected either by the drier for the AC or by the ABS pump. Remove your plastic headlight cover panels in the engine bay and inspect.

                OE bulbs are probably made by the same folks we'd typically buy from in the aftermarket, just have to make sure the spec is correct for the application as some bulbs will fit, but won't function.

                Comment


                  #9
                  Update!

                  A few issues were present, one due to the car's age, and another due to my idiocy.
                  Since at least one of the bulbs worked before I changed them, that was my first avenue to chase...


                  The grounds were all good, as was the switch (according to my multimeter)

                  For the right light:
                  The issue was actually in the right front parking light. The contacts were bad. If I held the bulb in the socket, the hyperflashing stopped. I tried to bend the contacts to be better in touch with the bulb, but ended up actually blowing fuse 23 instead (inevitably crossed a ground there somehow). Anyway, new turn signals were on order, so I bent the pins out completely, and left the car parked.

                  For the left light:
                  I learned that the two locators on the bulb are of uneven heights, which means there is only one way to put them in... and I had put them in backwards.

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