Side blinker light not working- Wire?

[LarryNH914]

2008 X3 E83

So, have a 2008 with a driver side blinker that is not working. Blinks fast as expected. Brought bulb, but no joy. The other signal lights on the Driver side work as expected (fast).

Took off working side light assembly on passenger side, put it on Driver side, and it does not work either.

Took assembly on the Driver side and plugged it into the Passenger side, it works.

So, both light assemblies work, but neither works on the Driver side.

My Multimeter on the contact plug shows some jumping around when blinker is on the Driver side (and static when blinker not on), but my multimeter is not an expensive one. only gets to 0.14 volts or so, but the pulse is probably quicker than the Meter can react? (Note to self, try on good side).

Sooooo, anyone else have an issue like this? How would I diagnose this? The wire goes through the metal fender wall, to where, I don't know....

Thanks,
Larry

[LarryNH914]

It gets a bit weirder.....

Tested the side marker on the passenger side, with a slow blink, it goes up to 9V...

But, while I was observing the lights from the rear, on the passenger side, it was the yellow top light that was blinking...
On the Driver side rear, it was the brake light that was fast blinking.... Is this a feature or a bug? Is the computer noticing no blinking from the normal light and switching to the brake light?

Anyhow, replaced the bulb on the rear driver side, but still no blinking.... WTH? Tested rear driver side blinker with a multimeter, and nothing coming from the contacts for the bulb.

Here is where it gets weird. Noticed a trailer connection module tapped into the wires. The trailer connection has LEDs for the blinkers and lights. When the Passenger side blinker is on, only the passenger side LED on the trailer connection blinks. When the Driver side blinker is on, there are 2 leds blinking... (Now that I think about it, perhaps not so weird if the computer decided to turn the brake light into a blinker, if that is a thing?, have to look at the markers on the lights.)

BTW, they used quick splices.... I hear bad things about these.

So, I am thinking that perhaps the Driver rear blinker wire was severed by the 3 way (actually 4 way, but 3 wires) connector used to connect the trailer light module box. If I get the rear blinker working correctly, perhaps the side marker will work.

[LarryNH914]

So, does anyone know if the Blinker circuit fails, the X3 fails over to blinking the brake light? Or, is there a short in the light controller?

[LarryNH914]

OK, so disconnected trailer wiring, no difference. Trailer wiring was not an issue.

Took multimeter to poke around. Ground good. BUT! The positive side was also good to ground!! That's not right! Where is the short.

To eliminate the wire being shorted out, I disconnected the LCM (Lighting Control Module, some call it the Body Control module). The Positive side showed no continuity to ground. So, apparently, the positive wire is not shorted out from the rear of the car to the LCM (part number BMW 3 450 190 or BMW 61-35-3-450-190).

Would I be correct in saying the LCM is bad? It looks like another LCM would need to be reprogrammed by a BMW scan tool. Darn! Anyone in Southern Maine that can do this?

Should I try a used one at $119 or a new one (superseded part) at discounted price of $550

If not the LCM, what?

[LarryNH914]

I brought a used LCM (using the part number on the module) off of ebay for $120, plugged it in, and all worked.

Supposedly, this module also stores the mileage, and one can plug in the VIN and current mileage using P A Soft ($80 for software/hardware). I have not done this yet. There is a yellow dot near the trip mileage, this may be the "Tamper dot" that would be cleared? From my understanding, if the ebay module had more mileage than the original, a tamper dot would not go on. But, not sure it is worth it on a 195,000 mile car. The mileage is stored in 3 modules and should match.

So, fixed for now.