A4 Courtesy Lights not working

[bobbinz]

OK, so I just bought an A4 Avant B6, not my first Audi, and on the whole I'm happy with my purchase. However I have a few niggling questions/queries. My belief is that it's a Base model, though I have the black roof bars which I'm told is a factory option.
I'm looking at the DIS upgrade, as just the remaining mileage is not telling me all I need to know. I may also do a/m parking sensors, if only to keep the wife happy (not a sexist remark, honest).

My plea for help/guidance however is re the operation of the rear courtesy lights and associated functions such as door open sensors and hence the auto lock function. There doesn't appear to be any circuit to the rear doors beyond central locking and speakers. I know that I don't have rear electric windows, (no biggy). But the problem I have nearly fallen foul of a couple of times is opening the back door and having the the central locking re-lock because the car hasn't sensed the doors as open, therefore the courtesy lights also go out much more quickly, or don't come on at all if say the car has been 'left' unlocked for a while. A pain if I'm belting the kids in!

I've noted that there is a fuse allocation, no.23, "Door (rear left / rear right)" but in my car this is not installed, no terminals, nowt! Is it a retrofit /option? I was looking at faulty micro-switches in the lock mechs, but am not so sure now, bearing in mind that I don't even have the relevant fuse.

Electrics on both the front doors behave as intended, as does the tailgate. I've searched the internet for various phrases that I'd expected to reap plenty of answers, but the nearest I got was the m-switches and I'm not convinced about dry joints in those, especially now I don't have a fuse OR it's associated holder.

So... any ideas or better still, knowledge of getting rear doors to play with comfort systems please.

thanks in advance

Tony

 

[DieselJake]

Don't quote me but have been told this is generally just a wiring issue, in my case it must be anyway as this dumb garage messed with my car and ended up frying the ccu (all at my expense ) when it was rewired one of the rear doors wouldn't show and all doors are now on the wrong side according to the driver display.

 

[bobbinz]

Jake, thanks, I've read several posts now, mainly to do with VW, but also Audi about dry/cracked joints on the door lock pcb. The microswitches are prone to failing in this manner, affecting all from Central locking to courtesy lights everything in between.

I came across another thread that suggested I check to make sure the fuse wasn't blown. Didn't bother straight away as fuses never blow! However, I don't even have fuse 23, the specific fuse to the rear doors. So was looking to find out if anyone had run up against retrofitting rear door sensors and associated electrics. Plus getting at the pcb in the door is a real headache.

I might also look into footwell lighting which I'm sure must be available, had it on my '98 A6, it'd be nice in my A4....

 

[swarcup]

The fuse is present when rear electric windows are fitted i believe as they are controlled via can-bus as they have a door control unit fitted, when rear electric windows are not fitted then the wiring for the lock etc comes direct from the ccu. I would start by looking at the wires inside the rubber boot from the car to the door as these are prone to breaking, from there i would strip out the lock mech and clean/grease up the microswitch. One of my rear doors was doing this and once i had cleaned up the microswitch it has worked ok since.

 

[bobbinz]

swarcup, thanks, I had considered the rear window mechs for 23, guess I was clutching at straws, especially after one of the threads I found pointed at 23 for the lights, don't really fancy pulling the lock mechs out, but looks as though that's where I'm heading. Heyho!

 

[quattrojames]

I had the exact same symptoms in my A6 when I bought it, and it was the microswitches in the door handles. If the previous owner didn't use the back doors much then it's common for the switches to fail. I didn't faff about regreasing them, jut swapped them for the ones off the A4 as I had them there.

 

[bobbinz]

I had the exact same symptoms in my A6 when I bought it, and it was the microswitches in the door handles. If the previous owner didn't use the back doors much then it's common for the switches to fail. I didn't faff about regreasing them, jut swapped them for the ones off the A4 as I had them there.

So the lock mechs on the A4 and A6 rear doors are common?

 

[quattrojames]

Mine were yes.