Rear Defrost Light Comes On While Braking?
Rear Defrost Light Comes On While Braking? I have a 99 T/A and since I've gotten it when I touch the brake the rear defrost light turns on...I don't have any wiring diagrams so I dont know if for some reason they share the same circuits or not but I'm pretty sure it isn't supposed to be happening. Any ideas? Theres no aftermarket wiring done but the EGR is removed and theres some tape around where it was. (Not done by me)
Joined: Nov 2003
Posts: 11,330
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The rear defogger control and the third brake light share a common ground. It is possible (unlikely but possible considering the symptoms) that the common ground location is no good and the third brake light is grounding back through the defogger control. You can confirm this by checking for power on the purple wire of the HVAC controls when you step on the brake - there should be no power on this wire unless the defogger is on. The common ground is a bolt in the roof under the headliner just to the left of the dome lamp at the back near the hatch. It is a black wire with a ring terminal on the end.
Ok I found the ground wire but theres no bolt that it goes under, where the hatch bolts thread onto is to big for it. The only other thing I can find is the screws that hold the dome light in but they don't work as a ground. Ideas?
Joined: Nov 2003
Posts: 11,330
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
There should be a hole in the roof panel reinforcement (close to where the 2-pin connector and the ground wire ring terminal are located) that was used by the original ground bolt. Get a self tapping screw of the right size to replace the missing original one and use it to ground the ring terminal.
Another option would be to cut of the ring terminal and splice on an additional length of wire that you can run to a more convenient ground.
Another option would be to cut of the ring terminal and splice on an additional length of wire that you can run to a more convenient ground.
