S124 Tailgate Wiring harness

Back in late 2023 the soft close mechanism on my 300TE became erratic.  Sometimes it would work and sometimes it wouldn’t.   Sometimes it would randomly come on when driving.  At the time, I assume it was to do with the mechanism, so purchased a second hand soft close and had it fitted.  It didn’t fix the issue.   Since I was about to go on a family road trip, I just unplugged it.

Over time, it became apparent that the issue wasn’t the soft close.  All the electrics had stopped working on the tailgate.  This became obvious when the bulb out warning came on.  The number plate lights were not coming on, the wiper was not coming on and so on.   Since the 3rd brake light is a bit of an afterthought on these cars, it is not linked to the bulb out sensor, but it was also not working.

It was clear that the issue was my tailgate electrics.   As everything was not working, it was obvious the ground wire had broken in the harness.   The ground wire is the thickest and is the most likely to break.

I had a couple of options.  Repairing this wire, or replacing the harness.  I elected to replace the harness.   I figured that after 30+ years and almost 400,000km, I would be playing whack-a-mole with the rest of the wires if I tried to fix them.   The trim in this area is very brittle and taking it on and off wasn’t ideal.  Plus it would end up being more time consuming and expensive.

I purchased a new harness from Kurth in europe and waited for it to arrive.   This job was also an opportunity to fix a few other things that needed doing at the time.   Some of my trims around the rear aperture were broken and I found a much better set for sale.   My 3rd brake light housing was cracked, so I got a reproduction one from OctoClassic.   There is also a long plastic piece that goes on the bottom of the tailgate.  Mine was all cracked, but I was able to buy a complete spare tailgate.  That car had been white with a palomino interior.  I took a piece of broken trim and went to autolac who made me a spray can in the correct cream colour for my car.

I was going to try and do this job myself, but after almost a year of not getting to it, it was time to send the car to a professional.    I’m glad I did as the job took four hours for somebody with experience.  It would have taken me at least double, probably more.

In the end the old harness was ok other than that one broken wire, but I am still glad I did it this way.

Its great to have the soft close working again.  When it is not, the tailgate rattles.  In addition, the broken 3rd brake light cover, aperture trim and the bottom trim all look so much better.   Now the car goes to the panel beaters to fix the damage from the P-plater earlier this year.