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Thread: Reverse lamps come on while driving

  1. #1
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    Reverse lamps come on while driving

    plus the beeping back up alarm... so annoying...

    every day now... intermittently...

    switch? short?

    other?
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  2. #2
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    Very likely to be the reversing switch - found under the shifter plate on the early models - although it could be the boot hinge wiring it is less likely - quite an easy circuit to fault-find as shown below:

    https://www.meeknet.co.uk/e31/e31_91.pdf#page=281
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  3. #3
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    ok this morning i opened my garage door with the reverse lamps on !!!! and that dinging...

    battery dead.

    removed fuses 12 and 17 for reverse lamps, no effect.

    disconnected battery and stopped of course... reconnect and lamps on again...

    nasty nasty nasty !!


    Quote Originally Posted by Timm View Post
    Very likely to be the reversing switch - found under the shifter plate on the early models - although it could be the boot hinge wiring it is less likely - quite an easy circuit to fault-find as shown below:

    https://www.meeknet.co.uk/e31/e31_91.pdf#page=281
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  4. #4
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    update... the batteries are not dead... 13.6 volts!!

    seems like im trying to start my car as if it was in drive, when it should be in neutral or park to start...

    some switching bewitching??

    WTF man...

    either the Gremlins have run rampant or i think somebody must have died in my car in the past...




    Quote Originally Posted by starship1701a View Post
    ok this morning i opened my garage door with the reverse lamps on !!!! and that dinging...

    battery dead.

    removed fuses 12 and 17 for reverse lamps, no effect.

    disconnected battery and stopped of course... reconnect and lamps on again...

    nasty nasty nasty !!
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  5. #5
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    It's not the reversing switch then! The trouble is that the car thinks it is in reverse when you try and start it due to 12V getting up the reversing light circuit.

    So, 12V is getting there somehow - most likely place is the hinge wiring, but, is there an 'always hot' wire that runs up one of the hinges? It would seem unlikely - I'll have a poke around the diagrams.....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  6. #6
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    There's no 'always hot' that runs up the hinges - although there is power that is on the closed-circuit system which switches OFF after 16 minutes.

    Have you fiddled with anything recently?

    Things are slightly complicated by the fact you have a Canadian variant - do you have DRL's?
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  7. #7
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    thanks Timm, in discussions with Wuffer we kinda both think it has something to do with the shifter plate, ergo it thinks its in reverse and wont start... but always shorted with no key, thats the mystery, unless yes its right inside the plate??

    i haven't fiddled with anything for a very long time and trunk relays.pdfyes i have aftermarket DRLs been on the car over 5 years now...

    i did notice a very warm relay in the trunk, nothing changed when i removed it... the one with the red circle...

    also removed fuses 12 and 17 from front, no change.
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  8. #8
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    That's the reason I discounted the reverse switch - disconnecting the fuses would have removed power to the reversing switch and to the reversing lights - and as they were on before you even got in the car then it can't be the switch.

    There will be a short somewhere - you mention you have custom DRL's - are the two contacts ts shorted together on the back of the bulbs? To shorten the possibilities, if you are in a situation where the reversing lights are stuck on try removing fuses until you find the source of the power - rear and main boxes - that would give us a much better chance of finding it.
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  9. #9
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    thanks again Timm,

    today i will remove the fuses and relays 1 by 1 and see if i can find a clue...

    funny though, with no key in the ignition, if i rock the shifter back and forth from park to 1st, the idiot lights on the dash blink on and off... and if i recall at one point they stayed on... with no key...

    ergo lending credence to my shifter plate theory...

    hmmm...



    Quote Originally Posted by Timm View Post
    That's the reason I discounted the reverse switch - disconnecting the fuses would have removed power to the reversing switch and to the reversing lights - and as they were on before you even got in the car then it can't be the switch.

    There will be a short somewhere - you mention you have custom DRL's - are the two contacts ts shorted together on the back of the bulbs? To shorten the possibilities, if you are in a situation where the reversing lights are stuck on try removing fuses until you find the source of the power - rear and main boxes - that would give us a much better chance of finding it.
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  10. #10
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    Yes, it certainly sounds as if it is something under there - possibly pull the cover and have a poke around....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  11. #11
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    update...

    pulled all fuses and relays 1 by 1, front compartment no change. boot lid fuses/relays had 3 anomolies...

    pulling fuse #43 cut all power to car... reinstalled.
    pulling fuse #33 cut all power to car... reinstalled.
    pulling relay K72 cut all power to car... reinstalled.

    furthermore, after moving shifter back and forth again a few times lighting up my dash lights, the car started... WTF? but the reverse lamps and dinging still going. turned off car and reverse lamps still on and dinging.
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  12. #12
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    Well, I love a mystery - especially when electricity is involved, but this one is peculiar! But, there is a link between the things that were removed and the reversing lights - and that is a RED/GREEN wire that runs to the trunk lights - this is supplied by F33 and K72. But there is more to this.

    As a start, there must be a short between the reversing lights and the trunk lights - and that will be in the hinge wiring - so that's where to start:

    https://www.meeknet.co.uk/e31/BMW_E3...ing_Repair.htm

    Once you have fixed that problem there may be more to do - but that's where to start - and, if you have joined the two contacts on the front DRL's remove those bulbs, Canadian models do all sorts of strange things with those connected....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  13. #13
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    this past spring my boot lid wouldn't open and the culprit was a broken boot lid hinge wire... in fact several wires were broken and i painstakingly soldered each one back together and shrink wrapped them individually...

    so this morning i had my 8 towed to a repair shop and according to Murphy's Law, when the car arrived, the reverse lamps were not on nor was the backup alarm ding happening... the car left my home with the reverse lamps burning...

    it figures...

    a thought came to mind when i was driving home last Thursday with the dinging going on, after a sharp left turn and the dinging would stop... then 2 minutes later it started again... maybe i should be driving left all the time...




    Quote Originally Posted by Timm View Post
    Well, I love a mystery - especially when electricity is involved, but this one is peculiar! But, there is a link between the things that were removed and the reversing lights - and that is a RED/GREEN wire that runs to the trunk lights - this is supplied by F33 and K72. But there is more to this.

    As a start, there must be a short between the reversing lights and the trunk lights - and that will be in the hinge wiring - so that's where to start:

    https://www.meeknet.co.uk/e31/BMW_E3...ing_Repair.htm

    Once you have fixed that problem there may be more to do - but that's where to start - and, if you have joined the two contacts on the front DRL's remove those bulbs, Canadian models do all sorts of strange things with those connected....
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  14. #14
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    At least we have a clue where the short is and the wire colours!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  15. #15
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    indeed... and the shop tells me its repaired and that it had a damaged wiring harness in the boot lid...

    no more details yet...

    thank you Timm...

    Quote Originally Posted by Timm View Post
    At least we have a clue where the short is and the wire colours!
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  16. #16
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    Timm, it looks like once again you were correct...

    it appears as though the trouble was in fact at the boot lid hinges area, of which i attempted repairs last spring but perhaps it was yet more issues?

    wrapped nicely with plenty of slack...

    in any event, problem solved and more importantly, you were right!

    thank you Timm boot right.jpgboot left.jpg
    "...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge

  17. #17
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    Always my pleasure to hear that it worked out!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  18. #18
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    Quote Originally Posted by Timm View Post
    Always my pleasure to hear that it worked out!
    Tiimm's the man! He diagnosed my "trunk/boot" lid wiring issue from across the pond as well.
    1993 850Ci.....18 years & 165,000 miles and counting!

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