Scirocco Register

Evening gents,

On these cold misty mornings, one thing that has eluded my otherwise gremlin free electrical system is the rear screen demister.

I have replaced the switch, the little light even comes on in the switch is on, so it's getting power. All connections seems sound (!) and I can't find any fuse related item to check on the fuse box. Odd...

Looking at all the window tracks, well, they seem to be in unbroken order, no obvious scratches through them that would cut the circuit.

Any ideas on what to check please?

Cheers

Russ

Broken wires where they pass through to the tailgate? Do you have a working rear wiper? If so, the fault is likely in the live feed to the heater. Otherwise it could be a broken earth wire.

Yes, the rear wash wipe is working fine.

I'll check if I'm getting power at the window element end, better get myself a multimeter!

If it is the element I guess I'm stuffed?

9 times out of 10 it’s a broken wire from where the boot lifts up and down.

Many thanks, I'll check that too.

Evening gents,

So got myself one of those new multimeters for dummies. It shows power getting to and from the rear demister.

https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1

I have seen some rear doors for sale stating that several of the 'tracks' are not working so theoretically some at least should be.

Meh...

Any thoughts...

I did find a new old stock wiring loom for sale on DE Ebay but the chap refused to post it to UK....

When you say power getting to and from the demister, do you mean 12v on one side and zero at the other?

Good question!

Will have a re-check. The gizmo has a circuit checker on it too, so I know power can get from one side of the window to t'other.

I'll have to get the manual out again. Wish I'd paid more attention in Physics class's instead of playing conkers and chasing girls!!!

So it sound as though at least some of the heater wires are good. The next step in the diagnosis would be to measure the voltage between each end of the heater and an earthing point. You will find an earthing point somewhere in the luggage compartment, likely under the mat.

With the ignition and heater switched on, you should get a reading close to 12V at one side, and close to zero at the other side. If you get 12V at both sides, that tells you have a bad earth connection. If you get zero at both sides, that means power is not reaching the heater from the switch.

I think you may have just struck gold. I didn't have anything turned on when I was poking around!

Duh...

Rule of thumb. If you're checking resistance or continuity through a circuit, you need the circuit switched off, with one probe at each end of the circuit (usually doesn't matter which way). If you're measuring voltage, you need the circuit switched on, with one probe (+ve) on the point in the circuit you are testing and the other probe (-ve) connected to earth (car body). And obviously with the meter set to DC volts not AC.