Heated Rear Window - basic electronics
Hoping that someone can help me with some very basic electronics advice (as I have no idea at all).
I don't think my heated rear window gets warm when switched on and I'd like to find out why that might be.
When the switch is ON the yellow light in the instrument binnacle comes on. Does that mean anything other than that the switch is in the ON position?
I have a digital multimeter but don't know how to use it. Is it simple to check if there is current arriving at the heater element in the rear window?
There don't appear to be any breaks in the heater element.
Any help much appreciated, as always.
Yes , it's as simple as you suggested. There should be a visible part of the copper strip where the electric cable joins it. You should be able to see the electric cable somewhere on the edge of the glass. Put the probe of the meter into the copper ensuring that there is a positive contact. Ground the other cable and turn on the rear demister. I think that you actually need the engine running to provide power to the rear demister due to the large power consumption. You should see 12v if the electrics cables are working. You might need to experiment a few times to check you are making contact with the positive cable.
I had the same problem and discovered that the cable was broken in the conduit which slides between the body and door due to the constant bending. It's a heavy cable so doesn't like being bent in the same place. Simplying replace the damaged cable avoiding a junction in the conduit.
Check that you have a circuit on the heater element. Check the resistance between the positive cable on the door connector and ground. You should measure a few ohms. There could be a break somewhere. I don't think that you can repair the individual element break that you have identified. Next time there is a frost forecast, turn your rear door to the wind and see if it clears with the demister
There is a special conductive paint available to repair broken heating elements on glass.I last saw it 20 years back but am sure there is still a market for it today,
Have trawled the internet for heat conducting paint - most reviews are pretty poor (including for that one that Halfords sells) but have selected one and ordered.
Will report back (with my 1 to 5 star rating) once I've given it a go.
So, I said I would report back.
I opted for this product as it wasn't the cheapest but not the most expensive and seemed to come from a UK company that operates in the electrical field. The product appears to actually be manufactured in Germany (so obviously good for G Wagons).
www.uk.rs-online.com/web/p/conductive-adhesives/1015621/
Anyway, it arrived next day. Tiny little bottle but it does seem to go a long way. The paint is actually nice and thick as opposed to some of the reviews of other products that complained those were very thin and the paint ran all over the place. I masked off the area on the glass and applied 3 coats leaving about 1 hour between coats. Removed masking tape the next day. The paint is actually silver so it's not a perfect match colourwise with the heated elements but if not for that then you'd be hard pressed to see the join.
Just checked with my multimeter and very nice circuit now flowing along full length of the previously damaged strip.
Bear in mind that my break was very very short so not sure how it would work with bigger problem but having said that I give it 4 stars (would have been 5 but for the colour match).
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OK - have tested the electrics and (a) I have a good 14.2v supply to one side of the window and (b) a good earth to the other side of the window.
So maybe it's just my imagination about it not working. I have given the inside of the window a really good clean so will check to see how it behaves next time it mists up and I switch on demister.
There is one of the copper threads going across the window that has a very small break in it though (maybe 1mm) so obviously that particular wire won't be working. Does anyone know of a repair solution to fix that problem? Is it possible to solder across the gap (please don't all shout "idiot" at the same time - I did say at the outset that I don't know what I'm doing)
Mark