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Help-2012 Astra J S model rear window demister button problem - Printable Version

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Help-2012 Astra J S model rear window demister button problem - irishastraowner - 9:th-Apr-2015

I have a 2012 astra and the light does not come on on the rear window demister button. I only baught the car 2nd hand.
Its the button with the white box and the wavy lines through it.
Can anyone point me in the direction of the possible problem

RE: Help-2012 Astra J S model rear window demister button problem - tucpal - 9:th-Apr-2015

welcome have you checked the fuse for rear demist

RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 9:th-Apr-2015

I TAUGHT AN ERROR MESSAGE MIGHT COME UP IF IT WAS A FUSE.
SO YOU THINK IF I JUST CHANGE IT, IT MIGHT WORK?
WOULD I BE ABLE TO TELL IF THE CURRENT FUSE IS GONE BY LOOKING AT IT?

RE: Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 9:th-Apr-2015

Hi and Welcome,

I would check the fuse 1st in case it is that have you checked through the fuse thread?
http://www.vxoc.org.uk/forum/Thread-Fuses

If it's not listed let me know and I'll look it up tomorrow for you.

You can tell if the fuse is blown by looking at it side on.

RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 9:th-Apr-2015

I looked the fuse (engine compartment) in circuit number 6 and did not look blown.
There is no fuse in circuit number 9 at all. I assume this is correct for an s model petrol.
any other ideas? As weather not cold I can't really test if demister working or not.
Does the engine have to be running a long time for the rear window demister to work?

RE: Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 10:th-Apr-2015

Having a look on TIS and I would also check fuse 17 in the Instrument Panel Fuses.

Here's a Schematic for the above.

[Image: Power%20Ground%20Controls%20and%20Subsys...rences.jpg]

Also fuse 18 in the engine compartment there is also a relay K04.

Here's the Demister Schematics for the above.

[Image: Defogger%20Schematics.jpg]

The Demister should work once the engine is started.

Also not all cars will have all the fuses relays etc.


RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 10:th-Apr-2015

I had a look at circuit 17 in the instrument panel. The fuse looks OK.

CIRCUIT 18 IN THE ENGINE COMPRMNT HAS A SQUARE FUSE THING(NOT SURE HOW TO TELL IF THIS IS OK OR BLOWN,ANY SUGGESTION? IS THAT "SQUARE THING" JUST A DIFFERENT TYPE OF FUSE?

WHAT DO YOU MEAN BY THE RELAY?

THANKS FOR YOUR INPUT BTW

RE: Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 10:th-Apr-2015

Yes it's a fuse mate I'll have a look after tea and see if I can give you any tips on checking them ones.

That relay will control fuse 6, 9 & 18 so if the relay is at fault them 3 circuits wouldn't work.

RE: Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 11:th-Apr-2015

Sorry I didn't get back yesterday.

the big fuse you should be able to tell by holding it up-to the light, if not you can pop the the cover off to look inside.

RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 12:th-Apr-2015

Switched fuse18 & 19 in engine compartment to test if it was the fuse.light would still not come on demister switch. As I said fuse 6 looks OK.
As all other instruments are working in don't think it's the relay.
Any further suggestions??
Any other way to test the window demister?is it possible that the light in the demister button is not lighting?

Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 12:th-Apr-2015

It could be a blown LED. You could also put a multi meter on the connector on the rear window (1 each side) and get someone to turn it on and see if you get a reading, or a test lamp if you don't have multi meter.

I'll see if there is anything on TIS tomorrow for checking the system.

Is the car still under warranty? If so get it booked in.


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RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 28:th-Apr-2015

What is a lamptest?
I still haven't been able to solve this problem.

Help-2012 Astra J S model rear window demister button problem - Rusty2009 - 28:th-Apr-2015

A test lamp is just a 12v light bulb with a positive and negative wire.


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RE: Help-2012 Astra J S model rear window demister button problem - irishastraowner - 2:nd-May-2015

I HAD TO USE THE REAR DEMISTER DURING THE WEEK AND IT LOOKED LIKE IT WORKED. The condensation cleared from the lines.
It looks like the lights for both back and front(not the 3 buttons in the middle) demisters are not lighting up.when I push the front one all the air gets sent to the front. I have taken pics to show but wasn't able to upload. Rusty do you have an email add I could send pics to?

RE: Help-2012 Astra J S model rear window demister button problem - everson38 - 26:th-Sep-2018

(2:nd-May-2015, 13:21:30)irishastraowner Wrote: I HAD TO USE THE REAR DEMISTER DURING THE WEEK AND IT LOOKED LIKE IT WORKED. The condensation cleared from the lines.
It looks like the lights for both back and front(not the 3 buttons in the middle) demisters are not lighting up.when I push the front one all the air gets sent to the front. I have taken pics to show but wasn't able to upload. Rusty do you have an email add I could send pics to?
Hey I was wondering if you any luck with finding out what happened with this?

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