[rear] defrost from scratch, mostly

[wadofplastic]

{ Please take a look at those threads before you start a new one. }

I did, actually, and couldn't glean much.

It was strange. When I got this car, [92 eclipse, 1.8l | n/t] I had the hardest damn time trying to figure out how to turn on the rear defrost. The lines are in the window, there's only a handful of switches...so after trying I don't know how many combinations of switches in different positions, throwing my hands in the air and saying HUZZAH!...
[I'm really not a dolt... I thought maybe it was like some puzzle game, like MYST or something]

I checked the manual that came with the car...and there was supposed to be a switch for it, but there wasn't -- just these plugged holes in the dash. But there are lines in the window, I said to myself....
[terribly mysterious...yeah?]

And so I inquired with the gal from whom I had purchased this car. It was then revealed to me that the car didn't come with defrost, but the back window had been shattered at some point, and they put in a defrosting window, but -- failed to run the wiring for it.
I guess they told her it would be too expensive or something.

So I've cannibalized the dashboard three-switch thing from the junk yard. There isn't, however wiring for defrost in the hatch [I suppose they just didn't put it in at the factory, maybe thinking that this car really wasn't supposed to have rear defrost.

Anywho. Question being, does anyone have any experience with installing this, from this point where I'm at with these things?

I've some experience with wires and electricity, not really in the car world, though. Should I just be going to the junkyard again and get a better-suited hatch for this matter...or?

Any insight or thoughts would be great. Imma newbie, so this was the only place I could put this....
thanks!

andrew

 

[loba]

The switch should act as a relay. Check the wiring diagram. As for the rear defrost itself, there should be two terminals. one side is grounded and the other side is the switched 12V source. I think the defrost is on a timer? I can never remember.

Here's the wiring diagram for it. Let me know if you have any questions.

Also, make sure you attach the timer, if you let it run full time it'll blow out the lines and you'll have to repair it, it's a pain in the ass.

 

[mjigga99]

Well mr. wadofplastic, I would make sure the defrost grid is in working order and not damaged in any way. Try to get a 12V power source to the trunk, either spliced from an audio amp power source or straight up from your battery. Find a spot on the passenger side of the hatch to place a ground. Attach a 10g wire or so from the ground to the terminal that should be sticking out of the grid on the passenger side.
When you have some frost or fog on your rear windshield, attach the 12V source to the terminal sticking out of the driver side of the grid. If the grid heats up, you can start planning your wiring and switch placement. Anyone here would be glad to walk you thru the rest.

 

[wadofplastic]

Wiring diagrams! Wo0t! Thanks so much, loba!
Yeah, the wiring diagram says the defogger is on an 11 minute cycle.

Think I'm gonna get these parts from the junkyard this weekend...
{defogger timer, relay]
is there anything I should be watchful and mindful for / about with these parts?

 

[wadofplastic]

Ugh. Stuff and things happen,
so have to shelve this project for a little later.

But still, in talking with a friend,
he said that since it seems /NONE/ of the parts are in the car for this,
that wiring the switch as it is meant to operate would require, and I quote,
'essentially rewiring the whole car'.

Gross exaggeration?