E38 wiring harness repair

I am not an expert, so take all information and instructions on this page with a pinch of salt. It is quite possible that they will harm you, your wallet, your car, or all three. If in any doubt at all, take your car to the professionals. You have been warned.

If you suspect that the wiring harness is damaged, then take a closer look (this has been reported as a common problem):

Take off the front wheel.

Remove screws holding the wheel arch lining.

Un-clip plastic lugs and remove lining.

Cable harness is now exposed.

Un-clip cable tie and inspect metal panel edge behind the harness.

Sharp edge tends to cut into the harness.

When harness is unwrapped, many torn, completely broken or fused wires become evident.


Torn and broken wires have to be cut and the ends cleaned (one wire at a time to avoid mixing the wires up). Slide a piece of heat-shrink tubing on one of the wires and solder the ends together. Use electronic grade solder and non-corrosive flux. Make sure that solder flows completely over the whole joint. Slide heat-shrink tubing over the joint and heat gently. For wires where only the insulation is torn apply insulating tape.

Spray moisture inhibitor on the wires and wrap in insulating tape.

Add a piece of foam tube (cut to fit) behind the harness to protect it from the sharp edge.

If you find any mistakes or want to suggest additional info that I should include, please e-mail me.