Rear defrost

[mikewest_08]

So I have a 86 t type with no rear defrost and I wanted to see if anyone knows someone or knows if you can install one in it. I live in Portland or so it would be a nice thing to have. Thanks


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[salvageV6]

Once you get the proper window glass in, you can run a 12 gauge wire to the front and a 10 gauge ground wire where G134 is, above the rear window.

The switch itself needs power on a 12 gauge wire from the power accessory circuit breaker location which feeds the power door locks, power seat, theft deterent etc.

It also needs power from the seat blt/acc. fuse, and a wire to the lamps circuit, and it's own ground wire to G104 which isn't a critical location just need a ground on an 18 gauge wire to run the timer and lamp in the switch.

Not too bad a job once someone installs the correct glass.

My headliner is out if you need some connection pictures.

Replacement glass must have the quick disconnect tabs on it for Faston or 1/4" style connectors, or you may have to silver solder leads to the copper/solder pads on the glass itself.

Not sure how they come as replacements....

 

[mikewest_08]

Pictures would be nice if you could and thanks for the info it helps a lot.


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[salvageV6]

For Starters....

 

[GNRick]

I found this one on ebay but if you search for a generic one you might find it cheaper. Another option is to get a rear glass with the defogger in it from a junk yard. Don't forget to pull the switch too. http://www.ebay.com/itm/NOS-REAR-WI...E-GM-BOX-/301302602201?_trksid=p2054897.l4275

 

[Bruce Urie]

Once you get the proper window glass in, you can run a 12 gauge wire to the front and a 10 gauge ground wire where G134 is, above the rear window.

The switch itself needs power on a 12 gauge wire from the power accessory circuit breaker location which feeds the power door locks, power seat, theft deterent etc.

It also needs power from the seat blt/acc. fuse, and a wire to the lamps circuit, and it's own ground wire to G104 which isn't a critical location just need a ground on an 18 gauge wire to run the timer and lamp in the switch.

Not too bad a job once someone installs the correct glass.

My headliner is out if you need some connection pictures.

Replacement glass must have the quick disconnect tabs on it for Faston or 1/4" style connectors, or you may have to silver solder leads to the copper/solder pads on the glass itself.

Not sure how they come as replacements....

Jeez, SalvageV6......you are good! You've always known your stuff on these cars.....you even helped me wire my rear view mirror with lights to both operate when the doors open, plus when using the switches on the mirror....you had me go test a few things, then told me how to do it...this is on my '87 GN, and it works just great! I really admire your knowledge (especially the electronics) and how helpful you are to the guys here, including me......face it, you're just a pro! You're such a positive asset to this community....... I hope this guy follows your advice....looks like he couldn't go wrong.

Bruce '87 Grand National

 

[salvageV6]

Those are crappy cell phone pics.
I was trying to photograph behind the plastic parts still in place, so they will be updated with better photos.

Also the rear seat was soaking wet so I found a leak from the trunk in my car so that's a plus....

All you need to have to generally work on these cars successfully is the factory service manual, and gnttype.org, and of course this site.

I assumed factory glass but of course there are aftermarket solutions as well.

If you wanted to skip the factory switch and associated wiring you could use a 12 volt triggered timed relay with 30-40A contacts and a trigger switch mounted anywhere you like for it, but the factory stuff just plain works good.

You'd still need a heavy wire from the fuse panel/timed relay out to the glass no matter how you wire it up and the good ground.

 

[1986BuickGrandNational]

Those are crappy cell phone pics.
I was trying to photograph behind the plastic parts still in place, so they will be updated with better photos.

Also the rear seat was soaking wet so I found a leak from the trunk in my car so that's a plus....

All you need to have to generally work on these cars successfully is the factory service manual, and gnttype.org, and of course this site.

I assumed factory glass but of course there are aftermarket solutions as well.

If you wanted to skip the factory switch and associated wiring you could use a 12 volt triggered timed relay with 30-40A contacts and a trigger switch mounted anywhere you like for it, but the factory stuff just plain works good.

You'd still need a heavy wire from the fuse panel/timed relay out to the glass no matter how you wire it up and the good ground.

Hey...quick question...u seem to know bout this so hence my inquiry....just installed my 3rd...yup 3rd defogger switch...when I turn it on the light lights up orange just fine...BUT when turned off the blue light doesnt backlight...all three switched I tried didnt work...what am I missing????