Irratic Tail light Problem

[Manolito]

I was following the wifemobile today at lunch and I noticed that she had no left brake light on her 2004 330i.

This evening in the garage, the car had no brake light or turn light on the left, and the running lights looked dim.

I pulled the brake light bulb and checked it, and it checked OK.

I put it back in, and I had no lights at all on that side for a while, then they all came back.

The only odd thing now is that the brake light on the left side comes on a half-second later than the other two brake lights.

Anyone seen this before?

Where is the ground for the left tail light assembly?

Thanks!

[gixerdave1983]

im not sure where the ground is but its definitely a ground problem

[Manolito]

Found the solution on another forum. Turns out that there is a bad design in the tail light plug that causes the ground connection in the plug to corrode and eventually heat up and melt the plug. Others have had the same problem.

The fix is to bypass the plug and ground the tail light with a separate wire. There happens to be an available spade connection on the ground trace in the tail light, so you can easily make a second ground and still be able to detach the tail light quickly.

You solder a short wire onto the brown ground wire above the plug, then put a female spade plug on the other end of the wire and plug it onto the ground trace in the tail light. Tape up the solder joint on the ground wire so it doesn't touch and short out a hot trace in the tail light.

[Manolito]

Turned on the running lights and turn light and blocked the brake pedal.

Everything was working this morning, but I still measured 2.5 volts between the ground trace in the tail light and chassis ground, meaning that I had a poor ground connection and the bulbs were working with only 10 volts.

I peeled back the insulation on the brown ground wire, and measured zero volts between the wire and ground. This meant that the brown wire was well grounded, but was not well connected to the tail light.

The astute observer will note that I turned off the lights before snapping the photos, else the photos would not have turned out well.

Since I had read that cleaning the plug was only a temporary fix to a design problem, I soldered in a second ground connection between the brown wire and the ground trace in the tail light (see photos).

[NikG]

Is it possible a relay fuse is on its way out
A friend had a similar sort of problem with an e36 model and thats what ended up sorting it out!

Hope this helps mate