Project E36 M3 - Replacing the Foglight and Harness Connector August 18 2021
One of the foglights went out on our E36 M3. No problem, just swap in a new bulb, right? With a new bulb in, the foglight still didn't light up. The problem ended up being a combination of the foglight itself and the harness connector. We'll show you how we replaced the foglight and the harness connector.
We started our diagnosis by removing the right foglight. Insert a flathead screwdriver into the hole in the cooling duct, and push aft on the tab that releases the foglight.
The photo above shows the tab that you are aiming for when you stick your flathead screwdriver in the cooling duct.
Once the foglight pops out, disconnect the harness by squeezing the two tabs on the connector and wiggling it off.
We turned on the foglight switch and used a multimeter to probe the connector for voltage. Sure enough, we got 12 volts at the connector. So that suggested that the issue was with the foglight itself.
We twisted off the rear cap on the foglight to reveal that the insulation on the internal wiring had crumbled away. A short in the wiring could very well have been what was causing our foglight to not illuminate. We brushed some liquid electrical tape over the wires to see if that would insulate our wires from each other and solve our problems. With the wires insulated, we plugged the lights back in, but unfortunately, the foglight would still not light up. We then removed the left foglight and hooked the right foglight into the left harness. It still didn't light up, indicating something with the foglight was still wrong.
I attempted applying more liquid electrical tape to see if that would work. Upon testing the foglight again, the foglight would light up momentarily and then turn back off. Tilting the foglight would cause it to go on or off. Pushing on the connector on the back would also cause it to go on and off. Further investigation showed the rubber around the connector pins was crumbling.
Switching the left foglight to the right harness and still having no illumination pointed to an issue with the foglight itself. Switching the foglight back to its original place, pushing on the connector and seeing the foglight go on and off pointed to an issue with the connector as well.
It was time to buy both a new foglight assembly and a new connector. Note that the failed foglight unit was a Hella unit, and we have noticed that the quality is not as good as the ZKW units. The fitment isn't as good, the wiring insulation isn't as good and the plastic seems more brittle.
We start replacing the connector by removing it. The connector comes apart by prying on these five tabs.
We magnified and read the part number off the back of the connector. Only the last 7 digits are printed. The full part number is 61131378417. We ordered a new connector and the 61130007445 pins that go inside. We're not 100% sure on the part number of the pins, because they were quite tight and didn't go on very easily. There was also some conflicting information between the vendor description and realoem.com. In the end, the pins we ordered did the job, but 6113007446 with the larger pins may be the correct part number.
There was not much slack in the foglight harness in order to work at the foglight opening, so we pushed the harness up into the engine bay to have easier access to it. You can see the old connector insulation was old and crumbly. It was time to replace these.
The new parts ready to go in.
The pins simply drop into the connector and the lid snaps closed to lock everything into place. We cut off the old connector and spliced in the new stuff.
Some soldering, heat shrink around each wire and then heat shrink around both wires made for a clean-looking repair. Make sure you don't mix up the wiring. If you are unsure, use a multimeter to see which wire is getting 12 volts, and the other wire will be the ground. We added a few extra inches of harness length to make any future servicing a little easier.
We plugged the new foglight in and everything works as it should. It was a fairly straightforward job once the diagnostics were completed.