Need help with rear defrost problem

[hawkeye405]

Hi guys,
The grid lines on rear hatch aren't functioning properly. When I start the truck, the 2 center grid lines warm up and stay on as long as the truck is running. When I turn on the rear defrost, the yellow light on the switch turns on as normal but the rest of the grid lines don't warm up. I replaced the switch and still no change.

Any ideas?

 

[Blckshdw]

The traces have tiny breaks in them, which doesn't allow the circuits (each line) to be completed. Do you have a meter and know how to test for continuity? You'll need to check each line to locate the break, they sell repair kits to bridge those gaps so your rear defrost starts working again.

Should be plenty of youtube videos if you're more of a visual learner

 

[hawkeye405]

I have a multi meter and know how to use it. I checked all traces visually and didn't see any breaks at all. What I don't understand is that the defroster turns on as soon as the truck starts.

 

[Mooseman]

Most of the breaks are usually under the black "bakelite", or whatever it's called, from the rubbing of the weatherstripping. It eventually wears through it. That's the reason the two middle ones aren't affected because they're not under it. If you put a strong flashlight on the outside, you will see what I mean.

 

[budwich]

I have a multi meter and know how to use it. I checked all traces visually and didn't see any breaks at all. What I don't understand is that the defroster turns on as soon as the truck starts.

what you have is two problems. the first is likely a stuck relay / switch for the defroster which is why its on at start up. The other problem is you have some broken runs which result is only partial defrost.

 

[hawkeye405]

Thanks budwich, I'm off this Monday and Tuesday so I'll have to find the relay and check for cracks with a flash light.

 

[hawkeye405]

Okay Mooseman, i found a few breaks, now how do I repair them? A new rear window is $500

 

[DAlastDON]

Okay Mooseman, i found a few breaks, now how do I repair them? A new rear window is $500

Use this or similar. https://www.amazon.com/dp/B000ALBZJY/?tag=gmtnation-20

 

[Mooseman]

You would have to redo the main line from the connectors up and down the sides on the inside of the Bakelite. It'll be ugly but it'll at least work.

 

[mrwitty_1]

If the breaks are in the Bakelite area I used copper conductive tape with conductive adhesive and ran a strip down both sides from top to bottom close to the Bakelite.

 

[Mooseman]

If the breaks are in the Bakelite area I used copper conductive tape with conductive adhesive and ran a strip down both sides from top to bottom close to the Bakelite.

What dimensions tape did you use? It can handle the amps OK?

 

[hawkeye405]

After searching some more on the web, I found this company that sells all kinds of defrost repair products as well as new kits: https://www.frostfighter.com/index.htm

I still have to figure out if I need to replace the whole defrost or just try repairing what I have.

 

[Sparky]

Curious how that turns out. Mine was totally busted except for those two lines as well, but even the lines themselves had thin/worn spots from something. With so many breaks the only option I had was to replace the glass for $500, or I just lived with it for 5 years.