Rear Heated Screen Not Working

[Stef Williams]

Speaks for itself really - now not working, but mirrors are working, still attached at the connector on the window so a bit flummoxed

 

[sidepod]

Do you have a voltmeter to hand, check if there is power at the window element when switched on?
If no voltmeter, use a bulb and a bit of cable.

If power but no heat then the element is duff.

If no power then try at the switch etc.

 

[Stef Williams]

Do you have a voltmeter to hand, check if there is power at the window element when switched on?
If no voltmeter, use a bulb and a bit of cable.

If power but no heat then the element is duff.

If no power then try at the switch etc.

None of the above but will try thanks

 

[mrcheesbrough]

Just wondering. Is your window a single or double glazed one? Ours is double and the heated window is pretty pathetic.

 

[Stef Williams]

Just wondering. Is your window a single or double glazed one? Ours is double and the heated window is pretty pathetic.

Yes its double glazed but was working fine???

 

[mrcheesbrough]

Hmm. You've got me thinking that perhaps ours isn't working. I'll have to look into it.

 

[Stef Williams]

Hmm. You've got me thinking that perhaps ours isn't working. I'll have to look into it.

Yeah exactly.......

 

[mrcheesbrough]

@Stef Williams. Did you ever get this sorted?

 

[zennorboy]

Mine's not working either. Independent T4 VW guru says there is power at the switch and that the mirror elements and double glazed rear window are all working...so there must be a break somewhere in the wiring, probably in the main line going to the rear of the vehicle. To access this, all the trim gubbins has to be removed!

As I'm still recovering from needing a new steering rack AND a broken cam belt I'll just have to make do with a chamois this winter.

 

[mrcheesbrough]

Mine's not working either. Independent T4 VW guru says there is power at the switch and that the mirror elements and double glazed rear window are all working...so there must be a break somewhere in the wiring, probably in the main line going to the rear of the vehicle. To access this, all the trim gubbins has to be removed!

As I'm still recovering from needing a new steering rack AND a broken cam belt I'll just have to make do with a chamois this winter.

Hey @zennorboy. What age T4 are you driving? I think I may of made a useful discovery but as mine is a 2001 with a double glazed rear window it may not apply to all ages/specs of conversion.

 

[zennorboy]

Morning mrcheesbrough

Very close to yours I would think; same colour too.

May 2002 California Event.

 

[mrcheesbrough]

Morning mrcheesbrough

Very close to yours I would think; same colour too.

May 2002 California Event.

Okay. Here's what I discovered. The double glazed screen isn't heated. However, as you're no doubt aware, it has wires connected to it as though it were. Now here's what I worked out - the circuit for the heated rear screen is in fact used to power the high level brake light. The power from the heated window switch terminates behind the rear right taillight as it is redundant and the original wire connects into the taillight (on the brake light circuit) thus powering the high level brake light using what appears to be the heated screen element.

Sorry for the longwinded explanation. There's a quick test you can do check this is the case on your Event model. You'll need two people. One to press the brake pedal and the other to disconnect one of the 'heated screen' connectors (behind the curtains in either side of the window) and check for brake light activity.

Mystery solved. Shame it's not heated though. Bare in mind the switch still operates your heated mirrors which is why it's still fitted on the dashboard. However this may only be the case on mine - let me know if you find the same with yours.

 

[WelshGas]

Okay. Here's what I discovered. The double glazed screen isn't heated. However, as you're no doubt aware, it has wires connected to it as though it were. Now here's what I worked out - the circuit for the heated rear screen is in fact used to power the high level brake light. The power from the heated window switch terminates behind the rear right taillight as it is redundant and the original wire connects into the taillight (on the brake light circuit) thus powering the high level brake light using what appears to be the heated screen element.

Sorry for the longwinded explanation. There's a quick test you can do check this is the case on your Event model. You'll need two people. One to press the brake pedal and the other to disconnect one of the 'heated screen' connectors (behind the curtains in either side of the window) and check for brake light activity.

Mystery solved. Shame it's not heated though. Bare in mind the switch still operates your heated mirrors which is why it's still fitted on the dashboard. However this may only be the case on mine - let me know if you find the same with yours.

Makes sense that explanation, as I cannot really see how a double glazed unit could be fitted with a working heating element as the heated glass would expand unlike the unseated pane.
I know when I got my 2014 the option was rear double glazed or heated, not both.

 

[zennorboy]

Thanks for the advice mrcheesbrough. I will get my electrics man to check this out properly, rather than me faffing about without not really knowing what I'm doing and I will post his findings here when I know.

I certainly have the the two connections behind the rear window curtains with wiring and I certainly have a double glazed unit. Why would VW put all that wiring there if the unit has no heating element? The double glazed unit and single glazed unit are/were obviously two separate part numbers...bafflingly!

And another thing...having never really looked before your advice, I'm amazed that there are live connections (if in fact they are supposed to be live) so close to presumably flammable curtain material.

 

[Stef Williams]

Thats interesting, I'll check the brake light scenario. Yes my heated mirrors work on the button

 

[mrcheesbrough]

Thanks for the advice mrcheesbrough. I will get my electrics man to check this out properly, rather than me faffing about without not really knowing what I'm doing and I will post his findings here when I know.

I certainly have the the two connections behind the rear window curtains with wiring and I certainly have a double glazed unit. Why would VW put all that wiring there if the unit has no heating element? The double glazed unit and single glazed unit are/were obviously two separate part numbers...bafflingly!

And another thing...having never really looked before your advice, I'm amazed that there are live connections (if in fact they are supposed to be live) so close to presumably flammable curtain material.

@zennorboy It's a simple enough test to see whether the 'heating element' supplies current to the high-level brake light. No need to employ an expert at an extra cost. All you do is unplug one of the connectors behind the curtain (either will do), get someone to press the brake pedal and look to see if it illuminates (I suspect it won't). Plug the connector behind the curtain back in, get someone to press the brake pedal and the high-level brake light should illuminate. I don't think the double-glazed window was ever intended to be heated, despite it looking like a heater element and there still being a dedicated switch on your dashboard.

 

[mrcheesbrough]

Thats interesting, I'll check the brake light scenario. Yes my heated mirrors work on the button

I'd be interested to know your result. I spent quite a bit of time studying wiring diagrams and investigating it on our Westy.

 

[zennorboy]

Despite any reasonable sense or logic, you are absolutely right, at least in my case. I have just performed the test...foot on the brake, upper brake light works, disconnect 'heated rear window' feed, foot on the brake, upper brake light doesn't work!

One can only presume from your investigations that double glazed rear windows are not heated.

Still surprising to me as my bus was ordered from Hanover with the full winter kit, extra insulation and heated everything...except the rear window apparently.

Thanks for that.

 

[mrcheesbrough]

Despite any reasonable sense or logic, you are absolutely right, at least in my case. I have just performed the test...foot on the brake, upper brake light works, disconnect 'heated rear window' feed, foot on the brake, upper brake light doesn't work!

One can only presume from your investigations that double glazed rear windows are not heated.

Still surprising to me as my bus was ordered from Hanover with the full winter kit, extra insulation and heated everything...except the rear window apparently.

Thanks for that.

Hurrah! Glad to of helped shed some light on this. I have a feeling that @Stef Williams will have the same result and we can all rest in the knowledge that were not meant to see out of the rear window in the colder part of the year. I'm sure there would of been some logical engineering reason as to why the double-glazed window wasn't heated. I guess we'll never find out.

Best make the most of it now while the warmer weather is around.

 

[CYCLOPATH]

Hurrah! Glad to of helped shed some light on this. I have a feeling that @Stef Williams will have the same result and we can all rest in the knowledge that were not meant to see out of the rear window in the colder part of the year. I'm sure there would of been some logical engineering reason as to why the double-glazed window wasn't heated. I guess we'll never find out.

Best make the most of it now while the warmer weather is around.

I do remember, from a post last year, that if you opt for a heated rear window , then you don't get the double glazed one, because the two are not compatible .
I would imagine if you look closely you will not see the heating elements in the window?

 

[WelshGas]

I do remember, from a post last year, that if you opt for a heated rear window , then you don't get the double glazed one, because the two are not compatible .
I would imagine if you look closely you will not see the heating elements in the window?

Yes. If you heated one side of a double glazed unit then - BANG. No window.