Thread: Tailight Fix
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Old 12-10-2007, 09:44 PM   #11
Registered User
Join Date: May 2005
Location: Toronto
Posts: 71
My Ride: '03 330ci ///M vert
Originally Posted by ssm1991 View Post
Thanks for the compliment.

I did the right taillight before since it was the one giving me the problem. I saw your post so I did the left one today -- this time with pics.

All photos are for the left taillight. Process is the same for the right.

The only materials and tools you need are:
- a 0.25" blade receptacle (available in Radio Shack, Home Depot or any electronics shop)
- a 5" strip of size #18 or larger wire
- rubber or vinyl electrical tape
- utility knife
- pliers

1) Release the taillight housing and lay it on the trunk.

2) Release the connector by pressing on the sides then pulling. Take note of the circled tab. That's the point we'll connect to later.

3) Cut a 5" piece of wire and strip one end about a quarter of an inch.

4) Insert the stripped end into the blade receptacle and crimp using any pair of pliers. Try pulling out the wire afterwards to make sure it's tight.

5) At the connector, the ground wire is the brown one. It's noticably thicker than the other wires.

6) Using a utility knife, carefully strip half an inch of insulation on the brown/ground wire 2"-3" from the connector.

7) Strip half an inch of the other end of the new piece of wire and wrap neatly (mine wasn't too neat in the pic) around the exposed ground wire.

8) Wrap tightly with electrical tape.

9) Plug in the connector again and insert the blade receptacle into the tab.

10) YOU'RE DONE!! If you've been having that annoying intermittent bulb-out problems and all bulbs seem to be ok, this is I think a more permanent solution. Replacing just the connector like what's done at the dealer will just bring back that problem after a few years. The problem is that the connector pin for the ground is too thin to carry all that current to the bulbs reliably. So eventually the pin builds up electrical resistance and will melt in some cases. Running a parallel connection using a thicker connector will solve it. (I'm an electronics engineer by education btw)

Thanks so much for posting this. I had this problem since I picked up my 330i, and I looked into everything. This weekend I saw that the ground wire connection had corroded and that the plug itself had a hole in the #3 spot. I pulled the wire out of there, re-made the connection and plugged it into that spot on the tailight - so far so good. No errors!

Thanks again!
Razkal is offline   Reply With Quote