On the E46 models, BMW has issued a recall to fix their E46 tail light fault. We created a step by step procedure to show the damage that is done and how to perform this repair yourself.
The kit below has both bulb holders and the repair cable (100K10107).
You may also find damage to the bulb holder connector (12527519956) and wire terminals (12521433217), at which point replacement is highly recommended to complete the job and prevent any further issues.
This was done on a 2004 BMW 330xi experiencing the intermittent tail lamp out indicator on the dash. BMW has issued a recall to repair all affected vehicles. This walk through was done on the driver’s side as that was the side that was bad. The passenger side had no issues, but was still upgraded to prevent this from happening there. The repair kit (100K10107) comes with everything to do both sides.
Remove the bulb housing for the left tail lamp and disconnect the plug. This is the culprit. The ground terminal is too thin to support the amount of current flowing through it causing resistance and heat to build up. A melted connector and corrosion is the outcome.
The ground pin slid right out. Notice the green corrosion on the wire also. This is exactly why the ground wire needs to be upgraded. That will be cut off and the new ground wire attached to it.
BMW does not cover replacing the bulb socket housing, but it should be replaced especially if it’s corroded like this one. The #2 pin is the black corroded ground pin in the top row.
These are the parts I used for the repair. I also replaced the corrector that was melted along with the #3 pin for the red/yellow wire since the ground wire melted through and that pin was corroded also.
I repaired the ground wire on the vehicle’s harness with a new terminal.
The long brown wire is the new ground wire with a larger spade connector that can handle the current demands. The bottom part as you can see is to connect to the vehicle’s ground wire. If the connector was still good the factory ground wire would have been cut in half and both ends attached to the new ground wire.
Plastic housing for the bare connector.
The last step is to attach the new spade connector to the ground pin on the circuit board. BMW was kind enough to leave an attachment point there, as if they saw this coming. Because of the damage the ground pin had I just bypassed the connector all together and went straight to the grounding tab. Now this piece can be reinstalled. Always check all light functions after this repair.