Rear Window Heater doesn't stay on?

[Berty]

Hi Folks,

 

This morning was the first time in a while I'd had to switch on the rear window heater/demister but the light on the dash only stays on for a few seconds and then goes off again and the window doesn't demist.

 

Anybody know why this could be and a workaround?

 

Thanks in advance

[Berty]

Also checked all fuses. Bit of a mess to have to remove the glovebox.

No fuses blown, fuses where they should be at least.

[PetrolDave]

Is your radio reception OK?

 

I ask because the rear window heating element is also used as one of the radio antennas. There is a filter between the element and the power & radio, which in earlier VAG models is known to fail.

 

I'm wondering is this is faulty and the BCM is not seeing the correct current flow into the rear window heater and turning it off.

 

Worth seeing with VCDS if the BCM has any fault codes.

[Berty]

Radio is fine, everything in the car is fine. The only thing plugged it was a Sat Nav into 12v so unplugged that and nothing.

 

I even tried a good slam of the boot to see if there was something amiss in there.

 

It's a 2nd hand car but a 2015 registration and seeing as I've only had it since August chances are it's never worked since I had it as it's the first time I tried it.

 

I don't have a VCDs. I did have a loan of a OBDEleven but didn't make any changes to the system that should relate to this. Only changed things like lighting settings and wiper settings. I just hope that one of the changes haven't mucked this up. Seeing as It's a Company car as well I might wait so until the next service and just say "Ummm, doesn't work" and see what they say unless there are other suggestions.

[Berty]

Update on this. No update as such.

 

OBDEleven(bought one as I've 2 VAGs)

 

No Faults at all.

 

Under Central Electronics

Basic Settings

Rear Window Defogger

It's NOT ACTIVE

 

Trying to change this causes the fuse to be engage 10 times. That's about it. It's a 30amp fuse and not blown, I've changed it also.

 

I can also perform a dash button test elsewhere in OBD and that comes back good. Fuse is good, button is good, rear defogger doesn't engage.

 

Would the assumption be really the problem is likely on the rear screen somewhere? Is that accessible without major tools or not worth the bother? Just let a dealer worry about it.

 

Thanks

[Neily03]

Might be worth asking in the MKII forum really?

[goath]

its under warranty so take it to a dealer!!!!!!!!!!!

[Neily03]

its under warranty so take it to a dealer!!!!!!!!!!!

 

Not unless it's got an extended warranty at 6 years old....

[glosrich]

Read the post...........its a 2015!

[Berty]

Wow, you turn you back on the computer for 5 minutes and that happens.

 

Yes it's a 2015, No I won't be asking in the MK2 forum and Yes I'm sure I'll ask a dealer but I don't want to be caught out with "We can see you've made changes to the brain of the car, warranty VOID etc"

[goath]

2015 registered car is not 6 years old......... unless I have missed 5 years of my life

[Neily03]

The original post made no mention  of what year the car is and the OP's profile says its a 2010.....

[goath]

It is under warranty and you have touched nothing..........remember that

[goath]

The original post made no mention  of what year the car is and the OP's profile says its a 2010.....

But the subsequent one did - read the thread!

[PetrolDave]

Would the assumption be really the problem is likely on the rear screen somewhere?

There are 3 possible areas:

1) the wiring to the rear screen - check for open circuit, especially where it goes between the body & the tailgate, in both the power AND the ground side

2) the rear screen is often also used as one of the radio aerials and there is a filter between the power lead to the rear screen & the rear screen itself which taps off the signal to the radio

3) the rear screen itself has been damaged and become open circuit

 

Check with the rear screen turned on whether you get 12V at the actual connections to the screen heating element. If you do, then it's fault 3) but if you don't then it's one of 1) or 2) and you'll need to remove some trim to work out which.

[Berty]

Thank you for your reply. As I don't think I'll be able to check if it has an electrical connection as (1) The Fuse is engaging(clicking sound) and (2) I don't really have the tools then I'll just try to ring my local Skoda guy. Had to get an oil top up there 2 weeks ago and it took 30 mins for an apprentice to do it. (Why you ask, because I didn't have to pay for it and could charge fleet company)

[Paulius55]

The rear screen is only used as an aerial on the hatchback, on the estate the aerials are in the side windows. It's not clear if the OP has hatch or estate.

[Berty]

It's a Hatchback but I think I'm towards the bottom of the problem here.

 

I rang the dealer to book it in and he says "Ring your fleet company first" and then I find out that a few months ago the vehicle was rear ended. Rear Bumper, wing and rear glass.(2 weeks before I got the car on my 1st day). Booked into the dealer now by fleet company. DEFO not my fault meddling with settings, thankfully.

[James@RRG_Skoda_Rochdale]

The relay lives in the same fascia board as the fuse panel. Have a check if the relay is clicking, find and remove it. I've had a couple with burned connectors so check them for scorch marks and replace if necessary.

[Berty]

About the relay. I could run a TEST using ODB and you can hear something click about 10 times(very quickly) and fail the test. The fuse, not burned out, is not engaging with a click when I press the button.

 

Anyway. It was in with the Stealers today and they said they are going to replace the Control Unit which of course isn't in stock. It will done next week so here's hoping it fixes it. It will be done under Warranty.

[Berty]

Update for those who search for something in the future on this subject

 

It was brought into the Stealer who Diagnosed a Warranty Failure in a Control Unit that is, I assume from OBDEleven, to be Control Unit 9. Not a part they regularly keep in stock so with waiting for a Garage slot to diagnose and then order the part and repair it took a while.

 

Then they advised that this completely reset the keys so my spare key is now redundant until I get it in to be re-coded as well.