Heated rear screen & door mirrors not working

A8L Chick · #1 10th January 2013, 09:47 PM

Well, Unlike Sloss's problem a year or so ago, I have neither my heated rear screen working nor my door mirror heaters working

??? Now, I've checked the fuses on the side of the dash panel that are associated with the rear window? and that was fine, I've also checked the HUGE fuse that is located in the boot (above the battery) and that is also fine. No codes shown up on the proper audi diag and now I'm totally stumped????

When you press the "demist" button on the control panel (in the car) the little amber "active" light comes on and then times off as it should-but it does diddly-squatt???

Am I missing something???

Any help greatly appreciated before this cold snap sets in???

Bex

sloss · #2 11th January 2013, 07:02 AM

Bex,

As the little warning light comes on that means there is lecky to the switch. That switch then energised a Relay which then feeds the rear window heater.

I don't know where that Relay lives but once you get to it see if it latches, if so then see if the load side ie the window shows continuity.

It may not be as simple as that with radio aerials etc embedded but then it's an '8

Stew,

A8L Chick · #3 11th January 2013, 07:08 AM

Quote:

Originally Posted by sloss

Bex,

As the little warning light comes on that means there is lecky to the switch. That switch then energised a Relay which then feeds the rear window heater.

I don't know where that Relay lives but once you get to it see if it latches, if so then see if the load side ie the window shows continuity.

It may not be as simple as that with radio aerials etc embedded but then it's an '8

Stew,

Thanks Stew,

It's a difficult thing to check on your own lol. I think the relay is 1 of 3(ish) by the large fuse above the battery???

If anyone could possibly confirm this I would be eternally grateful.

47p2 · #4 11th January 2013, 07:58 AM

Relay No.1 in the attached image

sloss · #5 11th January 2013, 08:18 AM

Quote:

If anyone could possibly confirm this I would be eternally grateful.

47P2 - Looks like you have a slave now......

Bex,

With a helper you should feel the Relay energise with switching it on and off.

If it does energise then check for live on Load side - if OK then look for fault in window wiring.

On your own with a meter it's still easy enough to check.

With everything off check all the Relay terminals for live - probably none.

Switch on Ignition and check again - 12v on supply side of Relay only.

Operate window heater switch - live onto Relay trigger and load side also comes live.

If all that works then it's likely to be the window itself - broken connection somewhere or knackered screen wires.

In that case switch it all off and check for continuity from load side of Relay. Take either side to earth to see if Window wires are OK.

If that shows open circuit then brick the window and claim on Insurance...

A8L Chick · #6 11th January 2013, 04:49 PM

Quote:

Originally Posted by sloss

47P2 - Looks like you have a slave now......

Bex,

With a helper you should feel the Relay energise with switching it on and off.

If it does energise then check for live on Load side - if OK then look for fault in window wiring.

On your own with a meter it's still easy enough to check.

With everything off check all the Relay terminals for live - probably none.

Switch on Ignition and check again - 12v on supply side of Relay only.

Operate window heater switch - live onto Relay trigger and load side also comes live.

If all that works then it's likely to be the window itself - broken connection somewhere or knackered screen wires.

In that case switch it all off and check for continuity from load side of Relay. Take either side to earth to see if Window wires are OK.

If that shows open circuit then brick the window and claim on Insurance...

Thanks for all help

LMAO at the last sentence.

I shall let you all know how I get on (as per usual lol)

sloss · #7 18th January 2013, 10:48 AM

Hey Bex,

Did you get it sorted out OK

A8L Chick · #8 22nd January 2013, 09:29 AM

Quote:

Originally Posted by sloss

Hey Bex,

Did you get it sorted out OK

Hey everyone.

No I'm afraid the new relay hasn't cured the issue. I still have no heated screen/mirrors (which is not fun in the current weather conditions)

I might just order the fuse for the hell of it-I haven't got a volt meter to test after the relay so I'm pretty stumped there.

I can't even see where the collectors are for the rear screen to check for a nic in the element/connections, can't see how it would get damaged anyway????

So, no, none the wiser

47p2 · #9 22nd January 2013, 11:39 AM

You need one of these!!!

snapdragon · #10 22nd January 2013, 01:43 PM

I'm not so sure it is the window itself as each element is in parallel, so if one was damaged, it would only affect that line rather than all of them.
The main ones at the sides are too robust to be damaged in normal use.
According to the SSP287_035 PDF, "The Central Control Module for Comfort System actuates the heated rear window over the Rear Window Defogger Relay J9. The relay activation information is supplied to the Central Control Module for Comfort System by the Climatronic Control Module."

Looks like CC panel sends a message via CANBUS to the Central Control Module and that sends juice to the J9 relay.
see page 45, but the relay output goes through C18 radio interference suppressor on the way, so maybe that is duff!
https://dl.dropbox.com/u/1273965/A8L...Components.pdf
https://dl.dropbox.com/u/1273965/A8%20fuses-pred-d3.doc (see p.17 for fuse and relay location if you haven't got that far)

Good luck