Always "in" reverse
 

I'd exhausted my search and self diagnostic avenues regarding this issue, so a post was the next step.
My '02 3.0 X5 with manual trans constantly thinks it's in reverse; that is the reverse lamps are always on and with the passenger side mirror is always tilted down (if the selector switch is in the correct position).
The reverse lamp switch is fine; I've tested it with a multimeter, tried a second one and tested it with a multimeter while installed (to make sure the selector rod was actually activating the switch.
The lamps etc stay on even with the switch disconnected, but there doesn't seem to be a short in the harness. I checked the resistance between the two sides of the plug and it's infinite (no connection/short).
Pretty sure it's a LIM issue at this point which probably requires the GT1. Just wanted to fish for some answers before shelling out money at a shop or for a GT1 of my own.
Thanks!
Jonathan

The reverse switch closes the circuit so with the switch removed completely there is no logical reason to why the lights stay on.

Do they go out when the car is off? or in position 1?

I know! The only non-LIM reason I could think of was a short in the wiring, but I tested it for continuity (one multi-meter lead on one prong of the plug, the second on the other prong, resistance was 1 (infinite)).
The parking-mirror tilt is the other give away... it's not just a lamp issue, the truck "thinks" it in reverse (unless the mirror cues of current flowing in the lamp circuit).
They go out and the mirror returns to it's normal position when the vehicle is off or in position 1.

Have you tried disconnecting the switch electrically at the tranny? I know you've tried other switches an all that but have you just unplugged it and seen if it still does it?

Yes, that was the switch to which I was referring. To be clear, the lamps are lit (and mirror tilted) with the plug that connects to the physical reverse switch (threaded into the trans) disconnected.

Well I have been zero help. I'm stumped. Maybe one of your Lighting Modules has gone (A3 maybe).

Sorry

I would think it's the switch/sensor on the transmission. Maybe disconnecting has same effect as being stuck in reverse?


I found this on another BMW forum:

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..
GL

That's a good point 545. Did you try shorting the plug that connects to sensor with a paper clip or something and see if that fixes it?

I believe he (she)'s referring to an automatic transmission, as the manual doesn't have a gear identification sensor or switch.
The only wiring, switches or sensors on this trans is the single, mechanically activated reverse lamp switch. It's almost identical to the one on my '69 2002: just a push button switch that is "pushed" by the reverse selector rod inside the trans and opens or closes a circuit. Disconnecting this switch would have the same effect as being out of reverse, as the circuit would be open. As previously mentioned, this has no effect, so I'm thinking it's a lighting module.
Thanks for the interest and the search though! Keep coming with more ideas!
Jono

maybe they've wired it to be in reverse as in selecting reverse breaks the circuit? Hence shorting the plug would confirm or deny the theory......

I like your thinking! But this would mean (since the functionality of the switch was tested) that putting the vehicle in reverse would turn off the lamps and return the mirror to home.
I'll try it anyway! Stand by for result...

Well not necessarily, the switch may complete the circuit all the time and break the circuit to turn the lights on. Remember these switches aren't hardwired to the bulbs they are connected to a control module so anything is possible.

Who knows but it's worth trying every avenue in order to save money......

Looks like you only disconnected the sensor, however you can bypass the sensor to test if it's the sensor or the wiring (maybe a short).

You can bridge the terminals from the harness to manually switch the rev. lights on and off and this checks the wiring.

I've attached a picture for a Honda and instructions (hopefully you can follow) having the same issue.

Since you are driving an MT, there is an easy way to test the switch.

Yes the key has to be on (engine off), otherwise the lights would still be on when u leave it parked in rev. gear and take the key out and walk away....

Put it in neutral and turn the key to "on"...your rev. lights will be on, if ur having the problem you described,

Now unplug the sensor from harness. The lights should no longer be on. You can bridge the terminals (SEE PICTURE-Hopefully a similar 2 wire setup for the X5) from the harness to manually switch the rev. lights on and off and this checks the wiring. If they didn't turn off at all, make absolutly sure u unplugged the right thing and then you can check the wiring.

QUESTION: Just to be clear, when you unplugged the sensor did the lights stay on? If they did then you are dealing with a "short".

So what's the verdict?

Thanks for the ideas, but in the original post I mentioned that the lamps are still on even with the sensor disconnected. I checked the harness for a short by testing for continuity between the two sides of the harness plug, but the resistance was still infinite (no short or contacting wires).
The sensor/switch works fine, as tested with a multi-meter.
As suggested I bridges the sides of the harness plug, but no change.

I reckon you have a short. It is electrically impossible for the light to be powered on but have no voltage coming through the harness.

You have a short somewhere so you'll have to find it

To be honest if it were mine I'd pay the $10 for a new switch, your multimeter could be bad or you might be doing it wrong just seems easier to me to get the switch and then once you've ruled that out you can focus on running up the line from the harness to find the short.

One question I didn't ask is how long have you had the X and has it been like that since you got it? Some people retrofit a switch into the reverse light so that they can turn it on for hooking up a trailer in the dark etc

A new switch was the first thing I did!
Besides checking with a multi-meter, I've traced the wires from the switch to where they disappear into the dash with a huge bundle of other wires with no luck.
It IS possible for the lights to be on with no current in the harness: in spite of the physical switch being similar to old ones the circuit is different. In old style circuits, the reverse light switch controls the current that goes directly to the lights (as simple a circuit as you can imagine); in newer Bimmers it just sends a signal to one of the modules to tell the computer the vehicle is in reverse (so it tilts the passenger mirror etc). If there's a problem with the module, the wiring might be fine but the car still thinks its in reverse.

Ahh we are talking about different harnesses obviously - I'm talking about the one that plugs into the bulbs at the back of the vehicle.

Good luck with it

With the lighting control module (LCM) taking sensor inputs and driving outputs, it appears to be your issue. Just as you have checked for shorts at the switch, you could check the plugs on the LCM to see if there is corrosion there or visible damage. I don't know how many separate lighting modules there are, but the schematics are available.

Just curious, was the instrument cluster changed?

The "Reverse detection" function is only active when this function is correspondingly coded in the instrument cluster. If the instrument cluster is coded for manual transmission, the program and selector lever display for automatic transmission is masked out.
The information "reverse engaged" is made available in the form of a telegram via the body bus (K-bus ).

I finally cracked and took it to a friend's shop, where by pure coincidence, they had a GT1 for a few weeks.
You're on the money with the cluster guess, although it seems to be a fault within the cluster. We decided to leave it alone, seeing as a new cluster is a dealer-only touch to the tune of $900.

Glad to hear you've narrowed down the issue.

The dealer will want you to pay full price however in the US you can call BMWNA and they will work out some deal to replace the cluster. For example you may only pay a percentage of the total cost, maybe only labor. May be worthwhile looking into?