I have an 86 with a high mount stop and the rear window has the defroster on it. Both work good ... together. The defroster when on works great, however when ever i step on the brake, for some reason it decides that it need to turn on as well, have no clue as to what the problem is. I thought it might be a ground, but im not really sure.

Any help?

And another piece of info. if the rear defroster is on so is the high mount even if im off the brake

 

your porblem is that the power wire to both the brake light and the defroster have a common contact point, either thru a short (most likley where the insulation has rubbed off both wires, or they have been pinched together). I have not been able to find a wiring diagram that shows the wiring for an 86 rear defroster. I have the rear defroster on my 82, but when I took a quick look, a connector I expected to find in the circuit did not appear to be there.

Assuming the 86 wiring is is same as the 82 wiring for the rear defroster, you should have a purple/white wire from terminal D of the Defogger contol (located in the center of the Insturment panel (I/P) going to connector C201 under the drivers dash on the left side near the wall. The wire out the other side of C201 is purple and runs to the back of the car to connector C336. This is supposted to be located at the top center of the end panel (back end of the car, the end panel is used to hold the lock for the hatch and the tail lights). This is the connector I did not find, but it may be under the trim work. This connector is supposte to open when the hatch is opened, turning power off the the defroster/defogger and I think the rear wiper, and maybe the third brake light also. This purple wire is the power source for the defogger.

The on line wiring diagrams I found for the 86 thrid brake light indicate that it is a yellow wire, starting at the brake switch and somehow running to the third brake light. The wire color for the tail brake lights is Light Blue. I am wondering if this yellow wire is also connected to connector C336 If so I would start there and see if you can isolated a common point in the wiring. If not they you will have to move up towards the front of the car, trying to isolate which section of wiring contains the common point or short.

Some disassembley will be required to trace the wiring harness through the car.

Maybe some one else will come by that has better diagrams or has an 86 car with the rear defroster on it.

Dave

 

Thanks ill start there, for i dont wont to burn out the defroster

 

Make sure the defroster wires are connected to the struts.

 

it looks like it might have been the wires on the struts, they were a little loose and i pushed them up farther, and so ill see

 

I just made a post and then I found this one. Thanks to 82CrossFire Z28 I started looking the defroster wiring and 3rd brake light wiring on the hatch. I found that the contact a the bottom of the hatch strut on the passenger side had came off. I would have never thought to look at that if not for this post. Thanks again 82CrossFire Z28 and pletch for this post.

 

Actually, Aperion posted the messagge to check the strut connectors

I am happy the you posted a question, were able to search, and find a solution. Seems like a lot of folks just post without searching

Dave