If you must clean the rear glass, scrub gently, and in the direction of the grid, not across it. ! Look for a bad switch, relay or timer. If you aren’t confident about your soldering skills, or aren’t ready to take a chance on cracking an expensive piece of glass, there’s another way. But the rear-window defroster clears only a narrow strip near the top and bottom  the window, leaving a wide strip of glass as translucent as a barrister’s door, and absolutely no visibility to the rear. The defroster comes only on the solid rear window. The second reason is simpler—the grid will overheat if it’s left on too long. You can simply lay the aluminum-foil tabs on the glass and press lightly with one finger to make connection with the grid. The dealer stated that they never heard of the failure. Generally, the tab that’s attached to the glass breaks off, leaving you with a dangling wire and no way to reattach it. If the switch is bad, you’ll be able to jumper the switch and get 12 volts beyond there for diagnosis. If it doesn't, check for a bad fuse and replace it if necessary. 6 years ago Dec 28, 2020 1 0 0 54 Belle Plaine. Make sure the rear defroster switch and the ignition key are turned on. By moving the tab along the damaged line, you’ll see 12 volts on the meter until you reach the break, where the voltage will drop considerably all at once. The element is imprinted onto the glass and some of your conductors must be cracked. Both play a part in getting moisture off the inside and outside of your windows. Let me know what you find. Take out the defroster switch and see which wire leads into it and which one leads out to the grid. The thin brown horizontal lines can be broken or scratched away from the rear glass, causing the defroster to only partially defrost the rear window. ... Good work Sir!! This 'ible is really about how to find the problem with a rear window defroster, not how to repair it. Your back window likely has lines through it, those lines are part of an electrical system. About: The official instructable for Popular Mechanics magazine, reporting on the DIY world since 1902. The blower motor itself can also go bad and need replacement. The dealer repaired things but it turned out that it required a battery charging an then a reset of the ECU module. The good news is that you might be able to troubleshoot the problem and fix it yourself without heading to the service department. 2,510 Answers. But you may need to replace the timer—which may be integrated into a larger box of electrical controls buried under the dash. Don’t try to bypass the timer. I also have the slider, and curiously enough the defroster only partially worked. The compound-curve style of rear window is several hundred dollars, and a large hatchback’s backlite on, say, a Camaro, can easily top a grand or more. Make sure the rear defroster switch and the ignition key are turned on. It sounds like a tab came off the defroster which is a common reason for defroster failure. Now move one tab to the center of the grid and measure again. Your rear defogger is probably performing like it's supposed to - they just doesn't work very well unless you run the AC compressor in conjunction. Any break in the line and it will stop working. Inspect your rear window for breaks in the defroster lines. Frost Fighter, a well-known defroster repair kit, suggests wrapping a little aluminum foil around the end of the wire to be sure you don't scratch the painted circuit. The smallest break or crack in the grid can cause the defroster to fail so careful visual inspection is needed. If you find a break in the circuit, move the test wire back and forth until you know exactly where it stops working. If it lights up, the grid is getting power. Rear defroster doesn't work and light on the center console doesn't even turn on. The car defroster is an essential safety feature, especially during those colder months. Add to this installation att the dealership or a glass shop—it’s definitely not covered by insurance. They heat up when the rear defroster is activated and begin removing the condensation immediately. Danger! Replace the fuse with a new one of the same rating, and check whether this fixes the problem. any ideas? This damage can be repaired with a Frost Fighter GRID Repair Kit. There’s usually a metal strip laid on the glass under the silk-screening. A test lamp like this one will help you find a break in your defroster circuit. The average defroster grid heats up to approximately 85° Fahrenheit and is very effective in clearing fog and ice from the rear window. Rear defroster fuse:If the fuse for the rear defroster is blown, the defroster won’t get power. Driver side is working, middle sliding portion and passenger portion are not. Now what? But sometimes, in the midst of winter, they don't work. There are two reasons for this. If the blower motor is malfunctioning, the defroster will not work. The Defroster. Don’t use window cleaner, as it may leave a residue of wax or silicone. You can test this with the defroster test lamp or an automotive circuit tester. Disconnect the wire closest to the passenger side of the car and attach the test lamp clip to the wire (not the little metal tab attached to the glass). Clean the area of the break with alcohol and a fresh, untinted paper towel. Attempting this repair in the middle of winter in your driveway will not get you the desired results. 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