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Brake lights "check" problem. Pls help.

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  • Brake lights "check" problem. Pls help.

    I occasionally get my "check brake lights" LED to light up while driving. The bulbs are OK (I did change them all to be sure), so it's a wrong signal. It happens at random, no real correlation with rough road. Did anyone have this happen? What's the remedy?

    The pain is that it happens at random, I went to see my electrician twice over it, and could not demonstrate the failure:grr:

  • #2
    It could be another faulty circuit in any of the circuits that service illumination.

    For example...my car would pop the check control for brake lights.
    Bulbs ok, so I added more tension to the contacts in the bulb circuit.
    No problems for a week then the check brake lights is back... by this time, the car had a problem with the left front flasher.
    Once the short in the flasher circuit was repaired.. no more check brake light advisories.

    m

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    • #3
      Try wire brushing all the bulb holders and using dielectric grease on the bulbs. A small rise in resistance from corrosion can cause a check light.

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      • #4
        I've had this problem many times (roughly 5). It could be the brake sensor wire. Possibly there could
        be some oxidation on the connections, or loose conections. Clean them up and do a visual inspection
        of the wires. Replaceing the sensor wires (cheap) would be the best attempt.


        Disclaimer: Remember, I know absolutely nothing, but it doesn't prevent me from having an opinion or suggestion. :

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        • #5
          Mine was a problem with the relay box above the left side rear wheel well. Fiddled with the connection and it goes away...comes back later though. I never tried to replace the box. This is a common problem.

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          • #6
            I think I got it fixed. I did some cleaning of the bulb holders and connectors first, didn't help. I then removed the lower part of the dashboard to get access to the brake pedal sensor. I sprayed it liberally with WD40 (lubricates and restores electrical contact), and I "massaged" every single wire without disconnecting anything. It did the trick, two days without the issue so far...:yeah:

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            • #7
              Mine has started to trip the "brake lights" check panel LED.
              it only happens when the air temp is below 70 deg and I use my right turn signal.
              I will do some checking this week.
              GraemeD

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              • #8
                I have an issue with my "brake lights" check light coming on every time i turn on the car untill i touch the brake pedal. after touching the pedal it goes away untill the next key cycle. Ive heard this is pretty common also... could this be a loose bulb connection also? Doesnt seem to me like it would be since it happens all the time.

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                • #9
                  NickB,
                  This is absolutely and perfectly normal. That's the way the system was designed. RTFM! :p

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                  • #10
                    Originally posted by pawelmontana
                    NickB,
                    This is absolutely and perfectly normal. That's the way the system was designed. RTFM! :p
                    Haha, hey thanks! PO didnt have the manual! lol. Another "normal" problem im curious about... Parking brake light and battery light, battery light stays on (upon startup) untill i release the e-brake and nudge the gas. Ive seen the pair mentioned briefly and have had no success with searching. Any explanations or links to explanations/fixes?

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                    • #11
                      I have fixed this random problem on my M3 and a 1986 325. In both cases, the cause was a faulty third brake light check relay. It's a 1" square circuit board inside the third brake light housing. You can bypass it or replace it. If you bypass it, you will lose monitoring of the third brake light only. Connect the two green/black wires together to bypass it. Replacing the board requires the use of a soldering iron.
                      According to Don Fields, this board tends to fail due to heat from the sun shining through the back window.
                      John
                      88 ///M3 Cinnabar
                      84 318i Black
                      sigpic

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                      • #12
                        Originally posted by GraemeD
                        Mine has started to trip the "brake lights" check panel LED.
                        it only happens when the air temp is below 70 deg and I use my right turn signal.
                        I will do some checking this week.
                        Graeme...You need a right front parking light/turn signal harness with the plug.

                        m

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                        • #13
                          NickB, PLease test out the search function.


                          Disclaimer: Remember, I know absolutely nothing, but it doesn't prevent me from having an opinion or suggestion. :

                          Comment


                          • #14
                            Originally posted by Mmark
                            Graeme...You need a right front parking light/turn signal harness with the plug.

                            m
                            I found the problem yesturday, if you remove the tail light assembly, in the bulb holder, the brown wire that goes from the connector to the metal frame had high resistance (5.5 ohms)where it connects to the frame. The small spade connector that you can just see, but can't remove without completely dissasembling light assembly.
                            Well I sprayed "De-Ox" in there & worked it with a pair of needle nose. That reduced the resistance to 0 ohms. Reinstalled the tail light & no problems. (so far)

                            The reason it would trip the "check" panel is that some voltage/current would "back up" through the stop light bulb circuit because all of the current could not get to ground due to the high resistance, and that would trigger the current sensor for the brake light.
                            GraemeD

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                            • #15
                              Originally posted by NickB View Post
                              I have an issue with my "brake lights" check light coming on every time i turn on the car untill i touch the brake pedal. after touching the pedal it goes away untill the next key cycle. Ive heard this is pretty common also... could this be a loose bulb connection also? Doesnt seem to me like it would be since it happens all the time.
                              Exactly the same happens to me!

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