Brake lights on all the time and dimly lit - after some stereo work '90 4-door 325i

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  • dcf_atl
    Noobie
    • Aug 2021
    • 11

    #1

    Brake lights on all the time and dimly lit - after some stereo work '90 4-door 325i

    Hello All
    My brake lights are on all the time and dim - '90 4-door 325i
    Googled but didn't find anything.
    Not about the check light
    Might not be related but yesterday installed a 4-channel stereo amp. Could we have tweaked a wire somewhere or something?
    And today . . . . both rear brake lights are continuously on and dim when key in the ignition. When I step on the brake pedal they brighten up but then go back to dim.
    Thoughts?​
    Attached Files
  • 82eye
    E30 Mastermind
    • Jan 2009
    • 1854

    #2
    time to download the etm and trace wiring.

    you can get a copy here : http://wedophones.com/Manuals/BMW/
    grab one before the resource is gone forever.

    Comment

    • dcf_atl
      Noobie
      • Aug 2021
      • 11

      #3
      Thanks 82eye (I think)

      closest I could find it "1991 BMW 325i Electrical Troubleshooting Manual.pdf" think that would be same for my 90?

      Comment

      • Panici
        Moderator
        • Dec 2009
        • 2311

        #4
        I would be inclined to use the '89 manual.
        Perhaps they did not make any revisions for the 1990 model year?

        '87 BMW E30 325is Turbo

        '99 BMW E36 M3 - - - '98 BMW E36 328i

        Comment

        • dcf_atl
          Noobie
          • Aug 2021
          • 11

          #5
          Yupp I printed out the "Stop Light" section for it -- but would sure love to hear a similar experience to save a few (or more hours)




          Attached Files

          Comment

          • reelizmpro
            R3V OG
            • Dec 2003
            • 9446

            #6
            Sounds like low current is getting into the brake light circuit. Where did you mount the amp? Did you run any wiring under the steering column?
            "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

            85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
            88 M3 - LACHSSILBER/SCHWARZE
            89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
            91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

            Comment

            • dcf_atl
              Noobie
              • Aug 2021
              • 11

              #7
              Thank you you ALL ! using a combination of all your advise we figured out that it was a bad cruise control module or something related to it. Process of elimination on things that shared the same fuse. The problem was solved by unplugging the cruise module above the ECU.

              Comment

              • Panici
                Moderator
                • Dec 2009
                • 2311

                #8
                Glad you got it sorted. Thanks for coming back and updating the thread.
                Helps when people search with the same issue.

                '87 BMW E30 325is Turbo

                '99 BMW E36 M3 - - - '98 BMW E36 328i

                Comment

                • 82eye
                  E30 Mastermind
                  • Jan 2009
                  • 1854

                  #9
                  Originally posted by dcf_atl
                  Thank you you ALL ! using a combination of all your advise we figured out that it was a bad cruise control module or something related to it. Process of elimination on things that shared the same fuse. The problem was solved by unplugging the cruise module above the ECU.
                  nice fix. thanks for posting.

                  Comment

                  • reelizmpro
                    R3V OG
                    • Dec 2003
                    • 9446

                    #10
                    Originally posted by dcf_atl
                    Thank you you ALL ! using a combination of all your advise we figured out that it was a bad cruise control module or something related to it. Process of elimination on things that shared the same fuse. The problem was solved by unplugging the cruise module above the ECU.
                    There you go. Good job. I'm very surprised it was the cruise module. I haven't heard of anyone having a problem with that before.
                    "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

                    85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
                    88 M3 - LACHSSILBER/SCHWARZE
                    89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
                    91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

                    Comment

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