Coming home lights and heated rear windscreen not working...

[Connorb5anda]

Hi all,

Ive recently purchased an S3 pre facelift and its great fun however there are a couple of minor teething problems I would like to sort out and was hoping for some help....

Firstly the heated rear windscreen doesn't work - Ive checked the fuses ( and the forums ) and have had no luck. So i put a circuit tester on the two soldering tabs here:





Which made a circuit!

I then noticed this on the other side which was a little more concerning.... not too sure why anyone would need to solder here....








Then I realised that just because I am getting a circuit at the two soldering point doesn't mean that the windscreen heating element is not broken as it could be making a circuit back into the car.

Is the next best thing to take the wires out of the module pictured above and test the wiring going through the car and forward?

also the rear heated button led stays lit only when engine is running - when just the ignitions on it goes off after a couple of seconds



The other problem is, and could be me being a numpty... the coming home lights do not work - no Led lighting ever no matter if I hold it tap it anything. Ignition on / off - light /dark it doesn't matter its dead. Anyway of testing this with VCDS?

My first suspicion is the clifford alarm that is installed - after about 30 seconds the immobiliser kicks in and seems to cut some power to the car. I have a booking in with some guys in Guildford to remove it as its a bit overkill where I live so I guess reviewing this once removed might make sure there is nothing complicating the issue....


Any help would be great - and very appreciated...

Connor

 

[OCD-A3]

Looks like there should be wires connected to the solder points in your second picture. See how the traces on the glass run to those points but do not continue between them, just like the first pic? Seems there is probably a similar module missing, did you look behind the trim there? Maybe some broken wires or a disconnected harness hanging? I'll take a look at my car in the daylight and see if I've got something connected there.

Not sure about your CH/LH lights, but you can check if they are enabled in VCDS. Goes your head lamp switch have a CH/LH setting?

Depending on what loses power when you turn the ignition off, it may be normal behavior. Many of the functions that work with ignition on (such as head unit and power windows) will remain functional after turning the ignition off, but only for a limited period of time or until you open the door. Not to say that the Clifford alarm isn't interfering in some way though.

 

[coxy8329]

The unit, 8P4 035 225B, in the first photo is part of the radio diversity antenna system. I doubt it is anything to do with the rear screen heating but I wait to be corrected.
Has the heat unit been replaced with an after market unit? As that may explain the to missing wires.

 

[Connorb5anda]

Looks like there should be wires connected to the solder points in your second picture. See how the traces on the glass run to those points but do not continue between them, just like the first pic? Seems there is probably a similar module missing, did you look behind the trim there? Maybe some broken wires or a disconnected harness hanging? I'll take a look at my car in the daylight and see if I've got something connected there.

Not sure about your CH/LH lights, but you can check if they are enabled in VCDS. Goes your head lamp switch have a CH/LH setting?

Depending on what loses power when you turn the ignition off, it may be normal behavior. Many of the functions that work with ignition on (such as head unit and power windows) will remain functional after turning the ignition off, but only for a limited period of time or until you open the door. Not to say that the Clifford alarm isn't interfering in some way though.

Hey,

Thanks for the response, Ive removed the lighting control switch today to find the plug un attached to the CH / LH button which would explain a lot.... I probably should have looked at this first before starting with VCDS! Anyway all is now good on that front!

The unit, 8P4 035 225B, in the first photo is part of the radio diversity antenna system. I doubt it is anything to do with the rear screen heating but I wait to be corrected.
Has the heat unit been replaced with an after market unit? As that may explain the to missing wires.

You are right man, that module is for the radio diversity antenna, had a check on ETKA which is still new to me.... So it would defiantly make sense that the other two wires are for the heated windscreen. I partially removed the trim again today and can see any traces of some wires that may have been removed!

I do have an aftermarket head unit - I'm a bit stumped on where to attempt to look for wires to trace from now!


If either of you guys get a second to check to see if there is a module that would be awesome, thanks again for the help!

 

[hollows wife]

there should be another module in the tailgate which is the diversity antenna module ,the heated screen runs through this as well. its bigger than the one in your picture and is hidden by the plastic tailgate panel.

 

[Connorb5anda]

there should be another module in the tailgate which is the diversity antenna module ,the heated screen runs through this as well. its bigger than the one in your picture and is hidden by the plastic tailgate panel.

Excellent, so once I've tracked that down I should be able to run wires possibly? ETKA suggests is has the part No. 8P4 035 225, do you know if this is in the lower tailgate trim? Ive tried to remove this but have had no luck - I have remove the two torq screw but its always feels as though the plastic is going to break.....

Thanks again pal!

 

[hollows wife]

yes its in the lower trim panel which is held on by metal spring clips , remove the screws then hold onto the recess where the screws were and just yank on the panel it will come off .

 

[Connorb5anda]

Got the lower trim removed and found what looks like the OEM connection.... however when testing the two pictured contacts with a circuit tester theres no luck. Does anyone think its worth running the wires to the point in the above picture where I am getting a circuit?

 

[Connorb5anda]

strangely there was another unplugged connection in the boot module :/

Thanks for everyones help its now all working!