Naughtie

Well this was a surprise!

A couple years ago, right around the same time I installed factory Euro taillights in my allroad, I began getting a "Right Rear Brake Light" fault when I opened my tailgate.

Initially I thought I messed up the VCDS coding for the new lights. But then the intermittent fault became a full-time fault.

I was still under CPO warranty, and discussed it with my service department. But because I changed the light modules, the service advisor warned me that if the fault was due to my work, repairs would be on my dime. So I stood down, thinking I'd tackle this easy repair when I had a spare minute.

In the mean time, on VCDS, I noted another strange error code, "Rear Glass Break Sensor." I believe it's the short, approximately 8-inch trace on the rear window right below the center brake light. However, this fault never resulted in a dash warning, and my rear defroster continued to work, so I disregarded it.

Fast forward to today, when I finally got around to disassembling my tailgate trim.

Boo-Yah! Look at this mess!

Two wires broken. Another hanging on by a strand. The two heavier gauge wires with a chunk of insulation missing. And the thicker black wire towards the bottom of the bundle is my coax antenna lead. All of this carnage is happening where the wiring harness straps to a "guide tray" mounted under the headliner, and transitions the wire to the moving hinge arms of the tailgate.

The woven carbon fiber jacket at the top left corner of the photo stops just short of the wear point. The "protection" from this point on is the sticky fabric wire wrap tape that's common everywhere else.

It appears that Audi's intent was to keep this from happening by providing a bunch of slack tucked in the headliner: in the second photo, I'm holding the bundle approximately in the "U" shape it's held in by two brackets.

Unfortunately, the zip tie that was right over the point of damage seems to have been cutting each time the tailgate was operated.

To add insult to injury, there are two (!!) gray-with-black-stripe wires in this bundle, and I didn't notice before cutting, so have an extra splice to make.

I was thinking of making a stink with Audi service since I brought this to their attention back in 2017 (I popped in for a visit today and their initial reaction is they wouldn't cover it), but the difficult part was pulling all the trim off, and I trust myself more than them to put this together in a way it's not going to rip itself apart again.

Sure would be nice if the engineers considered this an area of high (or likely) wear, and provided connectors and a short, replaceable harness for this portion subjected to repeated motion.

The car has 95k miles on it and I open the liftgate at minimum 6x on a normal day. Despite the high usage, this is pretty shoddy assembly and shouldn't have happened to this extent.

Naughtie

I should have documented this repair with photos. Shoulda woulda coulda.

I made my splices (butt connectors with good ratcheting crimpers) where the wires run straight in the tailgate, alongside the rear window, and where they run straight behind the rear-most passenger side window (d-pillar).

Other tools: T25 & T27 torx; trim removal tool; assorted pick tools; low profile T25 driver; electrical tape; fabric wire tape; 18ga wire.

This required removal of 5 pieces of trim:
- inside tailgate, rear of headliner, covers liftgate motors, pulls out straight back (no screws)
- d-pillar trim, piece w/ rear cover track, one screw in track @ top, one screw behind the cargo tie-down loop (also joins three pieces of trim)
- tailgate lower trim, 4 screws (two inside the emergency reflector compartment, one each under each brake light access panel -- total of 6 retainer clips along the lower portion roughly in line with the courtesy lamp, and 4 retainer clips along the upper portion - this piece also latches to the upper tailgate trim, and a pick tool or pry tool is handy for separating
- upper tailgate trim, single piece U shape around the top and sides of the rear window: sides are engaged with 2 retainer clips each side and pull in towards the center of the rear glass, and then 3 or 4 more clips along the top edge that pull out away from the glass
- small curved trim piece that covers the hinge and wire harness -- no clips, just needs to be pulled apart like opening a clam
- there's a trim retainer screw in the "saddle" that holds the main body of the rear cover shade; I removed this screw, but I'm not sure it was necessary

Two things to watch for: the tailgate trim has a bunch of rubber bumpers to keep the plastic trim from rattling against the steel tailgate, and many will fall out during the removal. The main tailgate trim can't be pulled too far from the tailgate without disconnecting the wiring to the tailgate close button and the courtesy lamp.

There are two wire retaining clips. One is under the headliner. I used a T25 bit and a 1/4" wrench to remove it, and bought a "Ultra Low Profile Hex Driver" to reinstall it. The other is at the pivot point (where the wires got eaten). It's held in place with a plastic rivet that can be pushed out with a pick tool. The only reason to remove this tool is to reinstall new zip ties to replace the three that need to be cut to remove the wire harness.

The remainder, I believe, is straight-forward wire repair. As for the area of damage, after making repairs, I wrapped the zip-tie location with a few wraps of electrical tape, then I slid the existing Kevlar sleeve up so that it protects this section of the wire harness where it contacts the first zip tie. I then applied another few wraps of electrical tape around the Kevlar sleeve. I used 4.8mm wide zip ties, wider than original, to distribute the gripping force over a greater area of the wire. The zip tie width is limited by the slots that are molded in to the bracket.

Reassembly is also straight forward. The only problem area I had rejoining the two tailgate trim pieces. A hook took was handy for engaging the lower piece to the upper piece where they clip together. For practice, I test assembled these two pieces on the workbench to see exactly how they clip together. Unfortunately, they can't be installed pre-assembled.

danzee

It looks like you've thoroughly explored the Allroad's tailgate. Well done!
My wife has a 2013 Allroad that needs the camera wiring and connector looked at. Can you describe what I need to do to get to it?
TIA

Naughtie

I wish I had taken photos along the way -- this would have made a nice walk-thru post.

Look through my written description in my second post above. Depending on where the wiring fault is, you may only need to pop off the two liftgate trim pieces. But if it's the wiring, and not the camera unit itself, I'd bet the fault is at the same location where my wires were compromised. If so, this will required the interior piece as well, just to get enough working room of good wire to make your splices.

danzee

Seems logical. Will do. Thanks.

It sucks that a car just a few months out of CPO warranty (and only 64K) shouldn't have a well-known design/assembly problem corrected under a warranty extension. There's even a TSB out that explains the problem and fix,and that explicitly disallows fixing it gratis after the warranty expires. Shame on you, Audi. That's bush league.

Naughtie

Oh, I haven't heard about the TSB.

I was still under warranty, but had just installed the ROW taillights when the problem popped up. So I took it in, but stupidly volunteered the change I recently performed, and was told that if the new lights were the cause of my trouble, I'd be on the hook for costs for diagnosis and repair.

I didn't crack it open to investigate until after warranty, so I was SOL, even though I had my previous service visit & specific complaint recorded in their system.

But truth be told, the most daunting task of this whole repair is getting the panel off and exposing the wire. The repair itself is very simple. And in the end, I have a lot more confidence in my repair job than the stock wiring at this hinge point.