Roadster trunk wiring loom repair

[KBH22102]

The wiring loom in my 01 M roadster was wearing and several wire casings had failed with visible wire exposed. This problem will eventually affect cars whose owners regularly open and close the trunk. The combination of wire crimping from the hinge and water exposure from runoff is a recipe for electrical shorts. I would guess that 75% of battery drain issues in roadsters start here.

BMW does sell a repair kit for the ‘Loom of Doom’ issue, but I thought to just reroute the wires inside the trunk to eliminate water exposure problem and cut down on crimping. I dissected the wire bundle from the weatherproof sleeve and then cut the wires one at a time and rerouted to an inner opening in the trunk lid. I cut a new hole in the deck lid liner and installed a grommet. I then threaded the cut wires one at a time and then spliced them back together. Once I was done and verified that all associated lights and trunk locks were functioning, I enclosed the bundle in flex tubing.

Yeah my solution may invite some snagging on trunk contents, but I typically don’t throw a lot of loose stuff in there so I think that issue should be minimal.

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[KBH22102]

I capped the stock grommets with small electrical plugs to seal them from water leakage. In time I’ll source some flat electrical plugs to cover those holes.


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[ProductUser]

Thanks for sharing and adding pics. I'll inspect my wire loom this weekend.

[Vintage42]

I like the way you staggered the splices. What is that tape used for wrapping before you put on the flex tubing.?
Ever since I got the car in 2012 and saw other DIYs, I have avoided opening the trunk as much as possible.
A few times a year I open it all the way. Most of the time I open it just enough to reach in.

[KBH22102]

What is that tape used for wrapping before you put on the flex tubing?

I used heat shrink tubing after I spot soldered each splice. I wrapped the bundle in 3M electrical tape, then installed the flex tubing, and then finished with another wrap of electrical tape.