Problem With Heated Rear Window

[Castorkid 11 1 Cars]

Dear all,

I am having a problem getting my heated rear window to work. I have a multi-meter and a basic understanding of auto electrics and am a bit stumped.

 

I have taken some pics of the back of the heated rear window dash switch and the grey connector block behind:

 

 

I've numbered the grey connector blocks female ends 1-5 and the back of the black switches male connectors lettered A – F.

No 1. Has a +ve feed from the fuseboard (P) via red wire 106 which is switched on with the ignition

No2. Is earth (I presume for the bulb in the switch?)

No3. Is a yellow wire that is +ve when the headlamps are switched on

No4. Is a red wire also numbered 106 again from the fuseboard (P) which has no +ve feed whether the ignition is on or not

No5. Is a white/cream wire numbered 107 again coming from the fuseboard (P) and I think should be the +ve feed to the heated rear window relay once the switch is pressed.

 

When the switch is connected to the grey block the following meet – 2C, 3A, 4F, 5D.

 

1, B and E are effectively redundant.

 

When the switch is pressed it seems to connect E and F.

 

If I connect 1 (+ve feed) with 5 (wire 107) the heated rear window has 11V across it and works.

 

When the switch is connected up to the grey block, the switch light comes on when the headlamps are turned on and then goes out if the switch is pressed. No voltage is detected at the heated rear window.

 

I have bought a second switch and the same happens.

 

Can anyone explain what’s wrong?

 

 

Key to Haynes manual diagram:

53 – Heated rear window

54 – Heated rear window relay

55 – Heated rear window switch

 

Thanks for looking

Cheers

NicK

[Weser 30]

Looks to me like you have answered your questions. Looking at the wiring diagram your right 106 needs to join 107 to via the switch to turn the relay on. The fact you have two wires labelled 106 and one isn't connected (assuming the grey block and switch are both correct) means that the one that is not connected isn't used. So I am assuming that you need a switched live on the other 106 wire pin 4.

 

This could be checked have you used the multimeter in the continuity test (beeps when the probes are put together) to find out which pins are joined when the switch is pressed. My guess is that when the switch is pressed Pins F and E on the switch are joined? Is that correct?

 

If they do then you need to find out why you haven't got a switched live on the 106 wire in pin 4. Have you checked the fuses?

 

What do the other numbers of components on the wiring diagram correspond to?

 

I'm no expert and must admit looking at the diagram I am getting a little stumped as to why the headlights light on the switch goes out when the switch is pressed. I can only assume that this is normal behavior as then the "heated window on light" would come on an take over, and this is not shown on the diagram.

 

Hope that helps.

[Castorkid 11 1 Cars]

Weser, thanks for the input. Yes, when the switch is pressed F and E are connected, BUT E does not connect to anything on the grey block, hence the mystery?!?

[Weser 30]

Ahh sorry I meant F and D? Are they connected when the switch is pressed? My feeling is still that you should have a switched live on the other 106 wire in pin 4.

 

Has the switch / heated rear screen ever worked? Whats the history of the car is it new to you? I.e do you know if the wiring has been tampered with?

[Castorkid 11 1 Cars]

Weser, I don't think the heated rear window has ever worked. Had the car 4 years now and only just started using it as a daily!

Switch defo doesn't connect F and D, only F and E.

Nick

[welshpug 1,657]

I think you may have the wrong switch, I have one here with a grey dot which matches the colour of the plug.

 

However it matches neither your switch or your plug!

 

terminal b is not present on my switch

[Castorkid 11 1 Cars]

Hi Welshpug

Mine is an '88 phase 1.5. would you happen to have a pic of your switch? I'm wondering if a previous owner tried replacing the switch and got the wrong type.

[Weser 30]

Yer that's what I was thinking something must be wrong! You could get it working by removing the spade terminal carefully from Pin 1 and putting it into the location of where the E leg goes. However this probably isn't a great way of doing it.