- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
check the heating element (the metal traces on the window) for breaks. a break will cause the circuit to not be complete and power will not flow. if you find a break, there is repair kits for it at auto parts stores. also check fuses. just because the indicator lamp is illuminating does not mean that power is making it to the back of your vehicle.
Between the rear passenger window and the back window is a junction where rear defrost wiring and radio antenna connect. Rear defrost wiring becomes loose and burns this unit out. when looking for replacement at salvage yard everyone of them I found had burned up. Lots of La Sabres w/o working rear defrost. I made solid connections for defroster, and added an antennae, not much point in repeating a system that will fail again.
There is a connector going to rear defrost on the rear window. Disconnect this and check for voltage with defrost on. If this is good, check resistance for the connection to window. This will tell you if the electrical is working or the element is bad for the window if there is a open reading on multimeter.
The main cause for the rear window not working is a disconnected wire at either side of the defroster grid. You can see where the body harness connects to the rear glass.
The second most liekly cause are broken defroster grid wires.
I would suggest to you to obtain a 12 volt DC testlamp, and check for voltage as follows, at the rear defroster.
Hook the clamp of the testlamp up to a known good ground. The back door latch 'hoop' is great. Next, turn on the rear defroster, and place the point of the tip on the extreme side of the back window, on the grid. Does it the tester light up bright? If not, try the other side.
The light, moving across the grid, should get noticeably dimmer, if the grid is functioning properly. The light will go out when you encounter a broken grid wire..
check your fuses first,with a test light,then if you have power there take your test light and turn on the rear defroster and probe the wires that connect to the rear defroster in the rear window.if you have power there it is a faulty defroster in the glass