If I have a defroster switch and a hatch made for a defroster, what do I have to do to add a defroster to a 86 trans am that didn't have one from the factory?

I dont guess the wiring as already in place on every car... that would be too easy

 

On the Firebird; most of the wiring probaly is.

I'll look into it a bit,..... But I'm guussing that you just need to add the relay, button, and maybe the heavy gauge Lead wire, and Ground wire on the other side.

I think the connector for the relay is on the dash harness already. The connector for the button might be there too - but that might depend on other optional equipment.... Might need to add a short harness for the button to the dash harness. Does the car currently have ANY option buttons on the dash already ?? ( SUB woofer, Hatch Pop ? )

 

The main defroster wire is typically purple and larger than the rest. It runs through the plastic conduit along the drivers door sill and then behind the rear interior plastic panel. IMO the junk yard is probably the best/cheapest option if you don't already have it on yours.
Looks like this:


*edit.

 

it has both the sub and the hatch, but no defroster. weird huh?

 

That image/descrition is not accurate. The picture shows a Trans Am FOG LIGHT button wiring harness.

Not as wierd as you might think; I've seen every combination of option buttons there.....

Remove the trim and check your existing option button harness. I have seen this little harness with 1-2-and 3 plugs on it so there's no telling what's plugged into your right now. When you remove the bezel you be able to see the dash harness -to- button harness connector. ( only used till 87? In 88? & up the button harness has no connector here; it's PART OF the main dash harness with all 3 plugs on it. )




Here is where the relay gets mounted.... I thiink the plug (without relay) is tapped up to the dash harness behind the dash housing.



Here is a picture of the dash harness C100 and C208 plugs. You can see the grey connector on the heavy gauge Purple wire that Scorpner described. Check behind the drivers kick panel for that grey plug on the Purple wire.





If you have the Relays' Plug, & the heavy gauge Purple Wire with grey connector near C100,..... Here is the rest of the system. ( in your case; you will need a 3 plug button harness rather then the 1 plug harness pictured; and the hatch glass ! )

 

Ah, so it is. It even has a purple wire on it too. Thanks for catching that.

 

wow John, that was an amazing post! thanks!

I guess I need to see what all I have already on the car so I can see what I need

thanks again

 

What is the Yellow and Purple wire harness? Those big wires.

 

Clutch pedal-to-starter Neutral Saftey Switch.