Late Heated rear screen switch not working? Here'show to fix

[Andy T 0]

My rear heated screen/demister switch started playing up a while back, requiring a good shove to work. After buying a couple of dud ones off ebay, I resorted to fix the original one, which was fairly easy with only basic tools, here's how -

 

Open the switch up by carefully prising the 4 tabs on the outside, then pull the two halves apart (careful, two small chrome bullets with springs attached will fall out! Ideally hold the switch with the buttons facing the floor to keep the pins in place.)

 

Once apart, there is a small white plastic plunger that pushes the copper contacts together - the plunger wears away over the years, mine looked like the heat had melted it.

 

Check the copper switch contacts, clean them with a screwdriver blade or smooth sandpaper. Now might be a good time to the check that both bulbs are working, with a continuity tester or battery.

 

Unclip the plunger assembly from its pivot point. Now carefully remove the white plunger & spring from its housing using a small electrical screwdriver. There is a small lug on the side of the pluger that restricts its travel - carefully remove it with a stanley knife. Now find a small metal nut or ball bearing that will fit into the housing before the spring and plunger - You will have to experiment here to get the right spring tension when re-assembled (I used a 2mm thick nut) refit the spring & plunger, holding it in place until the assembly is clicked back into the pivot point. Carefully rock the assembly back and forth to test - the spring pressure should hold the switch contacts together firmly.

 

To re-assemble - Drop the chrome pins into the two holes of the push switch housing (bullet ends first). Carefully refit the switch innards to the housing, click into place. Now go test!

 

It's easy to do, self explanatory really, I've probably made it sound more complicated than it is!

[fla 9]

Not so much switch related but my rear window takes AGES to demist and the door mirrors take even longer if at all. Any suggested checks for either? I cleaned the rear window thoroughl;y with glass cleaner hoping that would help, but it still takes just as long. The door mirrors dont seem to do anything, well today ther was no difference at all after about 20 minutes - rear was fine after this though, so i switched it off.

[pete_griff 0]

useful post - thanks :)

 

will hopefully have a crack at mine come the weekend (sympathise with your bad luck buying switches off ebay as well!)

[Andy T 0]

Not so much switch related but my rear window takes AGES to demist and the door mirrors take even longer if at all. Any suggested checks for either? I cleaned the rear window thoroughl;y with glass cleaner hoping that would help, but it still takes just as long. The door mirrors dont seem to do anything, well today ther was no difference at all after about 20 minutes - rear was fine after this though, so i switched it off.

 

I've had problems with the heated mirrors before, could be corrosion on the spade connectors on the back of the glass, or failed elements. Not sure why the rear screen would be slow to clear, do you have a multimeter? I could check the voltage/current draw across mine for reference.

[fla 9]

Not so much switch related but my rear window takes AGES to demist and the door mirrors take even longer if at all. Any suggested checks for either? I cleaned the rear window thoroughl;y with glass cleaner hoping that would help, but it still takes just as long. The door mirrors dont seem to do anything, well today ther was no difference at all after about 20 minutes - rear was fine after this though, so i switched it off.

 

I've had problems with the heated mirrors before, could be corrosion on the spade connectors on the back of the glass, or failed elements. Not sure why the rear screen would be slow to clear, do you have a multimeter? I could check the voltage/current draw across mine for reference.

 

Thanks for that andy. I presume it should 12V across the demist connectors?

[mattnorgrove 0]

Not so much switch related but my rear window takes AGES to demist and the door mirrors take even longer if at all. Any suggested checks for either? I cleaned the rear window thoroughl;y with glass cleaner hoping that would help, but it still takes just as long. The door mirrors dont seem to do anything, well today ther was no difference at all after about 20 minutes - rear was fine after this though, so i switched it off.

 

I've had problems with the heated mirrors before, could be corrosion on the spade connectors on the back of the glass, or failed elements. Not sure why the rear screen would be slow to clear, do you have a multimeter? I could check the voltage/current draw across mine for reference.

 

Thanks for that andy. I presume it should 12V across the demist connectors?

 

Aplogies for the Hijack, but if you could measure the resistance across a known good element, that would be very helpful to me, I know my switch works have cleaned the spade connectors either side of the element, (male and female halves) and receive 12v at the connectors when the switch is turned on.

 

Still get no demisting of the back screen though! I've checked for breaks in the actual element all the way across the whole rear screen and nothing is apparently broken, really starting to annoy me though, as with this cold weather we've had, a rear demister would be very handy!!

 

Thanks in advance chaps! :D

[nia573 0]

mattnorgrove - On my Mk2 Golf the rear window wasnt demisting & I noticed that the wires were broken as they pass through from the body to the tailgate (in the rubber convoluted tube). Once I crimped them back together everything worked fine!

I too was getting 12v at the terminals but it was the earth wire that was broken - I think it should be 12v at one side & earth at the other

Not sure if the Corrados suffer from this but it may be worth a try