Shared Knowledge

"BMW - Wiring Harness Repairs and Connectors"

2 March 2013


Summary: depending on location of wiring harness damage, either a partial harness may be available from dealer or other or wires in damaged harness can be repaired via new wires, soldering and heat shrink tubing. Wiring harness connectors are a different matter and can be hard to identify and order. Wiring harness connectors may have to be improvised as best you can.



BMW Z3, 1997, 50,000 miles.

Garage fire damaged right side (passenger in United States).

Wiring harness fire damaged: windshield washer pump; side marker to include connector and speed sensor cable from firewall.


Wiring harness repair:

With battery disconnected from car, separated burnt wires around washer pump.

One wire at a time, cut out burnt section.

Cut out enough so that remaining wire visually fine on both ends.

Using new wire of similar gauge, slipped piece of heat shrink tubing (available at hardware stores) over new wire, twisted new wire to one end of wire to be repaired and then soldered wire junction.

With new wire attached to old, slipped heat shrink tubing over soldered junction and using cigarette light moved under tubing, shrunk tube tight around junction.

Took another burnt wire and repeated, heat shrink tubing placed on wire and moved away from pending solder junction, twisted new and old wire together, soldered junction and then slipped tubing down over junction and shrank into place.

Repeated the same for other burnt wires in harness going to washer pump.

Once all wires repaired, took electric tape and wrapped entire length of repaired harness, doubling back once at one end to get 2 overlapping layers.

Using small cable ties, secured electric tape with cable ties many times to include where electric tape met cable harness good wire.


Wiring harness connectors:

What a headache.

I have been unable to find a wiring harness diagram that shows a part number for any connector attached to the harness.

I have even pulled a good connector free and copied down the number on it but Internet search and dealer search of parts finds no match.

You know that connectors are damaged in accidents and other, like my garage fire, but the dealership does not have a way to identify a specific harness connector.

So what to do?


In my case, I had to deal with missing side marker connector.

With new side marker in hand, I could see I need some way to connect to the 2 short pins in the lamp connector and it appeared these pins were about the size of pins common in personal computers (PC).

First tried some old PC audio cables I had but obvious pin spacing not close enough for me to push on an audio connector.

Then tried a 3 pin PC fan connector and it fit.

Clipped off wire attached to center of 3 pin connector and pushed PC fan cable over pins in lamp connector.

With connector in place and connected to 9 volt battery, lamp lit.

Taking a tube of black Silicone sealant, filled around my PC connector inside lamp connector to make a nice tight flush seal.

Now cut wire from wiring harness such that enough room to pull out side marker for bulb replacement when needed, slipped heat shrink tubing over pending solder junction and soldered wires from socket to harness.

Slipped heat shrink tubing over soldered junction and shrank tube tight around junction using a cigarette lighter.

SO the bottom line is to attempt to find some sort of pins that will slip over the pins attached to the part and make a connector using silicon sealant.

In my case a PC connector worked because of pin size and spacing but suspect there are many wired pins that can be found if you look at auto parts stores and else where.

Just be sure to use pinned wires of the same gauge as those associated with the part. Do not want to solder on small wires when the part is going to draw a lot of current.



Ron - Shared Knowledge Home