Another DIY project: clean chassis ground point behind right rear tail light
 

Just thought I would do a little write up here so folks could see what can happen.

I've been playing whack-a-mole with cleaning all the grounds, which can be the source of many frustrating electrical gremlins.

This past weekend I decided to repair the crumbling rubber gasket around the right rear tail light housing. It was also an opportunity to check the chassis ground point behind the housing. I had thought I fixed some lingering issues but they came back.

First I did some research and read a few threads on the topic. Here is a good one:
http://forums.pelicanparts.com/porsche-911-technical-forum/451961-any-tips-successful-removal-tail-light-assembly.html

Remove the 3 screws that hold the lens cover in place. There should be 3 rubber washers that go behind them. Our host also sells a handy dandy set of 6 black screws with the rubber washers.

Remove the bulbs. Good time to spray some contact cleaner in there. A fellow Pelican (Uwanna) recommended using a product called Deoxit D5. I have some on order now but I just used regular contact cleaner for this job.

http://www.mcmelectronics.com/conten...s5/200-040.jpg

Next up is removing the screws that hold the housing in place. I must be living right because I did not have a problem with the captive nut that hold the housing in place like so many others.

IMPORTANT: Put some painter's tape on the bumper. and the top of the fender. It is practically impossible to maneuver the housing without scratching the paint.


Once you get the housing out, you have some options.

1) Work with the housing in place.

2) Remove the housing.

Removing the housing can be a bit tricky. There are two wires to work with. One is the female end of the wire harness that connects on the inside of the engine bay. You may have some success by disconnecting the male end and pushing or pulling the female end of the connector through the engine bay wall. Also you might want to have a shop vac handy. There is all kinds of dirt, rocks and road grime stuck up in there.

What I chose to do was to remove the back of the housing (2 screws) and disconnect the individual wire connections.

If you take this approach you should take a picture first before disconnecting anything.

http://forums.pelicanparts.com/uploa...1456441241.jpg

I was pretty surprised by how clean mine looked. Note that there is a clay-like material that seals the back panel on the housing to protect it against the elements. A lot of that material crumbled off just by me touching it. When I put it all back together I sealed the housing with 3M 08008 Black Super Weatherstrip and Gasket Adhesive.

http://ecx.images-amazon.com/images/...L._SL1500_.jpg

Ok, so this is what I found behind the housing. Think I need to clean that?

http://forums.pelicanparts.com/uploa...1456441545.jpg

Last year I fixed a leak around the oil sender unit and I cleaned up what I could from inside the wheel well but I obviously didn't think about this. I degreased this whole area and then used my dremel with a small wire wheel brush and contact cleaner to clean the ring terminal back to shiny material. I also put in a new M8 bolt, nut and washer to make sure I had a good, clean contact.

Installation is the reverse of removal. :D

Hope this helps.

Right on! I did a similar project a couple years back, and for gasketing material, I ordered from McMaster Carr... picts in this link
http://forums.pelicanparts.com/porsche-911-technical-forum/744742-tail-light-house-seals.html

Nice find on the stuff from McMaster Carr!

Another thing I forgot to mention was the drain plug in the light housing was old and broke easily when I tried to remove it. It's really a good idea to take that out to get the housing out. Be prepared to order a replacement though.

Is there a diagram that shows all the ground point in the car? Does the current flow diagram show?

Here is a pic from another thread.

http://forums.pelicanparts.com/uploa...1357063084.jpg

The factory wiring diagrams show the ground points for each circuit and there is also a ground points table and diagram in the back of the Bentley.

Awesome thanks!!

Do you have a picture of the ground after you cleaned it up?

I don't think I took a pic. I used a new bolt and washer so it was all bright and shiny. :)