Problem with Rear Right Taillight – Possible LCM Issue?
 

Hey guys,

I was hoping someone might have some insight or have had a similar issue to what I am currently seeing with the rear taillight on my X5. I have had the problem before with either a melted plastic housing or a burn through hole in the metal but this is a new one for me. From what I can tell the light housing is working correctly and when bench tested all the lights work but when it is installed in the vehicle the bottom light refuses to light up. There is no corrosion on the connector to the light and we have not had any water issues. Has anyone had their Light Control Module fail in this manner? Is there a possible fray point for the wires? My understanding is that the LCM has to ‘detect’ the light otherwise it will not turn it on and throw a warning but the contacts are clean, the bulb is new and it works on the bench.

I am going to check the continuity of the line going to the taillight from the LCM this week but I wanted to see if anyone had seen this before. I thought it was going to be a quick fix but it looks like it isn’t. Any help would be great, thanks.

2001 X5 5 speed, 200k+ miles and going strong!

you should check where the male and female connector plugs into each other and check for continuity there. if that makes sense.

Are you talking at the LCM or the plug into the light itself?

the plug into the light itself, but ya at the lcm would be good to check too.the only issue I had with my tailights is a burnt spot where the bulb sits, which I just soldered up and been good for over a year now.

If it test o.k.on the bench but doesn't light up when you plug it in, you should verify that you have voltage at the connector. No voltage, trace the wiring back to see if you have voltage at the LKM. You could have a break in the wire.

So I just unplugged the A connector on the LCM and the lights went into safety mode, lighting up all the marker lights EXCEPT the rear right taillight. This makes me thing that the issue is not the LCM but a wiring problem. The investigation continues.....

keep us updated . thx

Finally got some time at home to look into this. The wiring tested ok so I moved onto the LCM and found this. Anyone know where to get an Infineon BTS736L2 chip? Looks like they are out of production.

Can't help with the sourcing the I.C. but assuming you do find one (or replace the entire LKM) the next question is... What caused the excessive current?

How are you at soldering SMDs? ;)

BTS736 BTS736L2 Smart 2 Channel Highside Power Switch Infineon Genuine | eBay