[bordermancer]

I want to replace the entire trunk lid wiring harness on my 2008 328xi sedan. The rubber boot between the car body and the trunk lid is ripped and I also found that a 16 ga brown wire was broken. Due to the age of the car I think I might start experiencing many more broken wires at this vulnerable spot that constantly causes the wires to bend and unbend whenever the trunk is opened or closed.

I found a new wiring harness for sale and thought that this might be the best route forward. Then I realized that when I'm trying to string the new harness into place it might be nearly impossible the get the two large ends of the new rubber boot through the small hole in the car body. There is no way to get my hand into the inside of the trunk to push the boot through the hole, so I would be forced to try to tug it through from the outside.

Has anyone managed to do this successfully without destroying the new boot or wires and without going insane??

[Serf27]

Remove the pins from connectors and feed the wires through the body.
Feed the wires through the boot and then re pin wires.
Tedious but will work if you cannot get the rubber boot through the car body.

The whole job seems tedious and I wouldn’t do it because one wire ripped.

[e90yyc]

^ What he said

I’ve got the same thing as you: Torn boot and a busted ground wire. I also considered replacing just the boot until I saw what a pain in the balls it was going to be.

In the end I soldered the broken wire (medium pain in the balls due to having to pull the boot down to get access) and said fuck it to the rest. Not worth all the hassle IMO.

[Efthreeoh]

I'm in e90yyc's camp on this. I also repaired the wire harness at the hinge flex point. I had several wires broken along with the ground wire. If you so desire you can find braided machine flexible wire and replace the OE wire at the flex joint. Or do what I did, which was removing the trunk liner and reroute the harness to get a bit more slack. Then solder the broken wire back together and use heat shrink. Then cut the accordion boot off and wrap the harness at the hinge joint with Tesa automotive wire loom harness tape. It makes for a better flexible joint at the hinge line. I fixed mine some 5 years ago and it's holding up excellently.

I've done this on three of my cars over the past 30 years.