I just put my new back glass on my blazer, it's got the rear defroster and wiper that I assume are in good shape. (The defroster is all still intact at least, the wiper appears to be all there.)

I'm going to head back to a junkyard to find the stock switches but I'd like to see a wiring diagram of how it all goes together first. My Chilton manual doesn't seem to have any info on the defroster or rear wiper circuits.

I'm assuming the defroster just works off of 12V, that's not too hard. The wiper is a little harder. Is the thing self parking? (This is a 1st gen.) Is the rear wiper multi-speed? From a little reading I'm thinking it's a two speed self parking motor with a case ground. That still doesn't tell me which wires are what though!

Has anyone done this? I did a search and couldn't find anything about adding the thing (lots of posts on removing it though!) Could anyone point me in the right direction? I guess I could trace a harness in a junkyard blazer but that's a serious PITA, I already know the wiring runs down to the floor and then up towards the front of the truck which means I would have to pull pretty much everything to trace it all the way.

Edit: I changed my mind for wiring the rear defroster in, I think I'll make a simple 555 timer to make sure the rear defroster only runs for 15 minutes or so. I could see myself leaving it on and burning crap up!

Any help is greatly appreciated!!!
Thanks!

 

Vehicle details might help move this along...

 

It's a first gen, 88 to be exact. Not exactly a W/T but not a Tahoe either. I'm not sure what year the glass came from, but it's got the trim all the way around (so that means pre 91 right?)

 

S-series then?

 

Oh, yeah. I keep forgetting there are Blazers that aren't S-10's

 

Anyone?

 

All I could find for your '88 was the rear defog schematics (attached)...

Do you know what year the rear window came off of?

 

Thanks for the defog circuit schematic, all I've got to do to get that working is build a little timer, shouldn't be too hard. I can't seem to find the original one anywhere so I guess I'll have to build one, this one here looks easy enough though.

http://www.zen22142.zen.co.uk/Circui.../5_30timer.htm

I'm not exactly sure what year the rear window came from but it would have to be older than 91 since it's still got the frame completely around the window. I know there are three wires and I think the case of the motor is ground so I'm pretty sure it's a two speed self parking motor I just don't know which wires are what. I guess I could just go probing stuff till I find something good

Thanks for the help!