djmccoy77

My OBC recently indicated that I needed to "Check Rear Lights". Along with one of the tail lights being burned out, my reverse lights were comming on when they weren't suppose to i.e. when ever the car is in gear (not just reverse). I thought this problem was a result of the burned out bulb and it would correct itself when I replaced the bulb, but it didn't. The OBC control indicator stopped the "check rear lights" notification, but the reverse light problem is still there. Any ideas about what's going on?

The_Andyman

Might be a short, or corroded connections.

Im not sure bout the E39 but the E36 seems to suffer a bit due to wiring being bent around evertime you open the boot and close it, it can cause chaffing to wear through the wires inside the sheath that protects them

Might be worth checking the wiring, I think it will be on the left hand side of the boot, near the shut line on top

The_Andyman

Or even easier it might just be the reverse light switch sticking, although im not sure if this will be under the gear stick or on the gearbox

djmccoy77

My guess is that it might be the reverse light sticking. If it was a short, I think the OBC warning would still be on. One question though, if the reverse light was indeed sticking, wouldn't it be on all the time and not just when the car is in gear? I don't know if I mentioned before, but the light turns off and back on every time I switch gears.

Stephan

I have exactly the same problem, we changed the both sensors on the gearbox without any progress
But my lights is on all the time...

Kind Regards
Stephan

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My Cars:
Alpina B10 Biturbo #91 -06

Al-Afghani

I have the same problem, I think it started after they replaced my clutch, I have been pulled over by cops etc. Annoying as SH**,

mateusz

did any one figure it out why is it doing that i had my clutch changed by amco and my car is doing exactly the same thing.

Bread

Damn, I was hoping to find a resolution to this issue on this board. I've got the same problem with the reverse lights coming on in every gear. I believe this is why the cruise control no longer works as well. I've replaced both the backup light switch, and the gear identification switch to no avail. Has anybody had this problem and found a solution?

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Jason

'00 E39 M5, '88 E30 M3, '78 IHC Scout II, '99 Ducati 996

mad dem21

I had the same problem about a week ago. My reverse light and mirrior would dip in any gear. Frist I thought it was the back up light switch and replaced it. Didn't do a thing. The way I fixed it was easy. The gear identification switch has a wire connected to it. That same wire splits in two and plug into a sensor that is a little forward of the gear identification switch. I just switched the two wires, somehow the wires were disconnected and someone put them on in reverse. problem solved..

Bread

Hmm, fishy. Who would be removing the connections to those two switches? They aren't in the way of any kind of maintenance procedure. This would only make sense if your trouble with the reverse lights happened directly following a visit to a mechanic. If the problem started randomly, then this is not a possibility.

I just got back from inspecting the transmission. I see only two switches, and two wire harness' on the drivers side of the transmission. RealOEM confirms this. The two wiring looms do come together and run side by side up over the tranny and through the chassis, but they do not splice together at any point. They are two separate harness'.

Upon detaching the connectors you can see that each sensor has two wires inside (the gear selector switch has both wires moulded into one strand of insulation making it appear as a single wire). I tested both switches for function:

Gear identification switch: Continuity test reveals that the switch is in a normally closed loop position. Current harness connection colors: Violet/Purple Brown/Orange

Backup light switch: Continuity test reveals that this switch is in a normally open loop position. Current harness connection colors: Grey/Black Grey

These switches have opposite functions, so it's easy to see that if the wiring harness' were reversed that the backup lights (mirror tilt, PDC, etc) would come on in neutral, rather than in gear. Yet this is not the case for either of us. The reverse lights DO come on in reverse. They also come on in every other forward gear. This leads me to believe that there is a problem with the gear identification switch circuit. These two circuits work together since the PDC works in reverse AND first gear. Unfortunately I don't have a wiring diagram resource to verify which wiring goes to which plug. Can anybody assist in this matter?

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Jason

'00 E39 M5, '88 E30 M3, '78 IHC Scout II, '99 Ducati 996