New to me, 1998 750iL. There is a warning on the dash (I think - missing pixels) about checking the brake lights. Took a video of the brake lights, since I can't be in 2 places at the same time. Interesting result. It seems the 3rd brake light works just fine, but the taillights do not.
I always thought the 3rd brake light and taillights were in (more or less) the same harness and ran from the same point, controlled by the same brake light switch, though ending at different places. This car has 120k on it and has been very well taken care of, however that does not preclude some knucklehead doing strange things. The taillights are not oem, they have clear upper lenses. I just picked up a 1998 740iL for parts, that I could swap out the light assemblies with. I have tested the bulbs (DVOM), they are good.
Any thoughts or suggestions would be helpful.
Thanks
Mike Drives:
BMW's
E24 - 635CSiA - (1) 1985 (US)
E24 - 635CSi - (1) 1985 (EC)
E31 - 850iA - (1) 1991 (Black)
E31 - 850iA - (1) 1991 (Calypso Red)
E32 - 740iA - (1) 1994
E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
E32 - 735iL - (2) 1990
E32 - 750iL - (1) 1990
E38 - 740iLA - (2) (1) 1997 & (1) 1998
E38 - 750iLA - (1) 1998
E38 - 740iA - (1) 2000 "Short Sport"
E39 - 528iA - (2) - 2000 & (1) 1997
Also:
2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
2014 Dodge Dart Rallye (Daily Driver)
2007 Mercedes Benz CL600 (Brabus SV12S)
Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
1967 Buick Riviera (2)
I put a jack handle between the seat and brake pedal, then power the seat forward till the pedal is depressed. Then I would check fuses with a test light to verify fuses are OK. Then I would test the brake light sockets themselves to verify voltage to them.
Take a close look at the bulb sockets, sometimes the contacts get burned from the heat of the bulbs. Had a similar problem with my son's 98 750. Had to replace the taillight assembly.
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00 740iS
84 635 (euro)
88 M6
84 745i
88 325iX
92 850i (6 spd)
Solved!
Since I can't watch the brake lights and push the pedal, I just used my phone and shot a movie. The only brake light I had was the 3rd one. Started digging around and found both outboard bulbs burned out, however both inboard bulbs tested good. Got to digging around some more and discovered the BMW harness does not use a separate wire for each bulb (inboard/outboard). The taillight itself must have those wires soldered together. The harness in the aftermarket taillights were looking for a separate wire, so there was no connection to the BMW harness. Consequently, with both outboard bulbs fried and no connection to the inboard lights, no brake lights.
The fix. Remove taillights and connect both inboard and outboard hot leads together via solder and heat shrink and voila! We have brake lights.
Thank you gentlemen. You helped me think outside the box.
Regards
Mike Drives:
BMW's
E24 - 635CSiA - (1) 1985 (US)
E24 - 635CSi - (1) 1985 (EC)
E31 - 850iA - (1) 1991 (Black)
E31 - 850iA - (1) 1991 (Calypso Red)
E32 - 740iA - (1) 1994
E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
E32 - 735iL - (2) 1990
E32 - 750iL - (1) 1990
E38 - 740iLA - (2) (1) 1997 & (1) 1998
E38 - 750iLA - (1) 1998
E38 - 740iA - (1) 2000 "Short Sport"
E39 - 528iA - (2) - 2000 & (1) 1997
Also:
2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
2014 Dodge Dart Rallye (Daily Driver)
2007 Mercedes Benz CL600 (Brabus SV12S)
Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
1967 Buick Riviera (2)
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