Rear Wiper Works When No Key In Car!

[fatgut]

I'm asking if anybody has had this fault on an estate before in order to save me some time on the detective work. Already have a multitude of other problems to fix in just the tailgate area, so keen to be as quick as possible. (Gas struts weak, tailgate glass won't open again-this time I'm doing it!) Today's C5 new trick which made me think I was losing my sanity was when the tailgate was open, the key was in my pocket, and I saw the wiper suddenly sweep. It then continued to do so all day, just the odd bit of wiping, seems linked to tailgate being opened or shut, and I think it seemed to do it once when I shut a back door too. Hope it's not doing it when car parked unattended,unable to monitor today. It can stop with the wiper half way across the screen. No idea if it would do it with when driving as had really wet weather up here all day, so rear wiper on non-stop when on move today. Used the so-called search facility on this site found zilch so reverted to usual plan b and manually trawled all posts and found one which mentioned similar problem, but no desciption of any fix/result. My guess is I'll be getting into the tailgate interior and looking for water ingress/shorts/corrosion/broken wiring/poor earths as per usual! Any short cuts will be very greatly appreciated, thanks.

[Randombloke]

My guess is I'll be getting into the tailgate interior and looking for water ingress/shorts/corrosion/broken wiring/poor earths as per usual! Any short cuts will be very greatly appreciated, thanks.

 

My first port of call would be the rubber cable shield on the extreme LHS of the tailgate when you are standing behind it. There have been other posts on this site or the Yahoo one about finding cable damage in here. It's easiest to see when the glass is open but the main tailgate is not.

 

There is also a loom that is partially hidden by the near side plastic hinge cover.

 

I have a random glass section of the tailgate opening problem which I have to write up for this site.

 

BTW, it's possible to get the glass open by removing only a few of the poppers that hold the tailgate trim in place. Start under the wiper at the top, and then progress towards the nearside then down the side towards the bottom. You only need 6 to 7 poppers out before you can get your hand in and move the plunger. The plunger goes up, not down - I removed some more before realising my mistake.

 

When the glass part is open, you then need to remove the 4 Torx screws that allow you to remove the housing for the high level brake light. This will allow better access to the cables mentioned and will allow you to see if you can get better access to the struts? In addition to these 4 screws, the high level brake light is also held in place by 2 of those trim type plastic studs that nearly always break when you remove them so I keep 3 or 4 in the car as spares.

 

Good luck!

[fatgut]

Thanks for that once again randombloke, I did give that most exposed bit of loom in the rubber cover a wiggle in the hope that it would magically reproduce the phenomenon, but it didnt, so at least I know where to start now, and I'll roll it into starting the tailgate glass repair too, sometime after Christmas. Just read your latest post on the random opening tailgate glass - that one sounds even worse, the more I learn about this car the more I fear for my future leisure time!

[fatgut]

;) Fixed it no problem, was indeed one clearly broken wire within the rubber boot connecting tailgate to body at top left. Snapped right through, insulation and all. Suspect this will not be the last of these here as is filled with an amazing number of VERY thin wires which are inividually surprisingly inflexible. The short piece of wire I used to patch in was a lot more flexible than those in the loom, and was very similar in thickness/core size. The wiring is really kinked at this point when the tailgate is shut, so a real weak point I think.