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      11-13-2012, 11:51 AM   #1
brad bedell

Drives: E90 335 and S54 Z3M
Join Date: Oct 2012
Location: dallas tx

iTrader: (1)

LCI LED tail lights, why they go bad.

As these cars are going out of warranty, you guys might want to know about this cheap fix. I'll do the other light after I make sure this one is good. When I do, I'll write up a DIY.

History Overview:
Service bulletin:
LEDs in Rear Lamp Inoperative
E90 (3 Series) from August 31, 2008 to February 2, 2010
The LEDs (Light Emitting Diodes) in the outer left or outer right rear lamp are inoperative. Affected are the
LEDs for the parking lamp/tail lamp or the turn signals. No Check Control message is displayed.
Corrosion of an internal connection within the tail lamp
Replace both outer rear lamps (left and right), even if only one side is inoperative. Refer to Repair Instruction
REP 63 21 180.
All lamps are to be retained intact by the dealer, awaiting either:
A parts 1. return request to send parts to BMW
An indication to scrap the parts based on information provided in the dealer's scrap report, at which time the parts are to be destroyed to prevent reuse."

That leads me to today:

I picked up some of these 'warrantied lights' recently for the purpose of trouble shooting. It's certainly NOT the connection in my case. However, if it were the connection, a bit of dielectric grease on the contacts will prevent the corrosion. BMW certainly knows this and would have 'cleaned the connection and used some grease' instead of replacing all the lights.

I suspected they had a bad solder joint. So I disassembled the lights and re-flowed the joints at the connectors between boards. I noticed when bench testing with a 9v battery that I could get them to all light up and flicker a bit if I put pressure on the solder joints.

The light came apart reasonably easy with a small screw driver. I pried them apart slowly by twisting the screw driver. They are glued on with a plastic cement or maybe even something like superglue. It's a very light bead, so breaking it apart was pretty easy. Sealing them back up will be a bit more of a chore, but not impossible. I'll get the big boy camera out to reassemble them after I repair the board.

Anyhow, this is the initial bench test:

I touched up the solder joints at all these connections shown by the pen. (at all the white wire connections)

I need to hook it up to a 12v power source to verify. I'm just using a 9v battery.

After testing a few times. I decided to stress test my 'fix' and toss it around on my desk a little and retest after each 'toss' to look for bad connections. I found I had to retouch a few of LED's. They were easy to identify by pressing down lightly with my finger on the LED itself.

Looking at the board, most of the connections are not shiny like a good solder joint. They are dull which leads me to believe the manufacturer of these boards didn't program their robot quite right. It probably needed a bit more solder and a couple more milliseconds of heat.