rear demist wiring

[hymodyne]

Greetings,

I have a GT6 MK III that is just about ready to get put back on the road. I've been working on it for about 2 years now, a frame off restoration. All wiring is working, except I cannot find the wire that powers the rear demist. it should be BL/White or just plain White according to the diagram, but I do not see any such wire coming out of the harness under the dash. Can I power the this circuit from any 12V wire? Also, I don't have a rear demist indicator light with bl/wh wires powering it, only one with purple/black wires going to it.

Just trying to button up the dash and would like to not have to open it up again...

James

[rotoflex]

Predominantly Purple with Black stripe should from the horn relay to the horn pushbutton.
What's hooked up to the horn button & horn relay now?

The Demist (heated backlight) wires should be Predominantly White with Black stripe.

This photo is from a few years ago, but you can see the demist switch at top center with the WB & Green wires.


Does your wiring harness seem to still be original, or re-wrapped?  Tomeorrow I will have time to Assume The Position & investigate from which branches of the wiring harness the indicator lamp & switch wires come.

FWIW, here's a late GT6 Mk3 diagram which is different around a few points, but I think demister wiring is not one of the differing points.
http://i66.photobucket.com/albums/h276/rotoflex/Triumph%20GT6/mk3-wiring-variant-1.gif

[John Bonnett]

Hi James, I know just what you mean about not wanting to take out the dashboard again, I've been through it myself.

If you have the loom for the car, the black and white heavy duty cable should be there. You will have a grey plug and socket which joins the rear wiring loom to the main loom and this will be located somewhere in the passenger compartment near the bulkhead. The lighting wires are in the plug but the heated rear screen cable is joined not by the plug and socket but by bullet connectors but it is right next to the plug and socket.

The demister warning lamp on my car is in the rev counter; a red lamp.

If you have to take a new feed do make sure that the cable is capable of handling 10 Amps.

I hope this helps a bit

John

ps I hope your screen works after all this effort. My looked perfectly fine but it doesn't work.

[John Bonnett]

I've just found this picture of the switch connections

[hymodyne]

Thanks for your helpful replies!

Its the heavy bl/wh wires that I cannot find... There's a wh/green heavy wire and the solid green wire. in the area of the dash that aren't connected. I'll start there.

Again, many thanks.

James

[rotoflex]

Please notice that on my picture, the gauge on the left is not the OEM water temp gauge, but a Smith's combo mechanical oil pressure/water temp gauge.  The red wire to the instrument lamp going to it should be the same as the OEM temp gauge.  The two wires with the unconnected blue terminals at the end are for the OEM electrical temp gauge.

[hymodyne]

Thanks to the good images of the backside of the rear demist switch from you fine fellows at clubtriumph.uk.org.,I  came to find out that my car has a green and white heavy wire for the switch, not a black and white wire. tested the contacts at the hatch and got a good reading.

going to put the gearbox tunnel in place in a few days and install the heater hoses and outlets.


james

[John Bonnett]

Well done James, another conundrum solved. The next hope is that once fitted the transmission tunnel doesn't have to come out again.

John