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Jeep rear defroster problem

archie2

archie2

Addicted Member
Since I've received so much good information from AK on audio gear I thought I'd give this OT thread a shot. I have a Jeep Grand Cherokee that has a rear window defroster that won't shut off, even when the ignition is off. As a result my battery gets drained. I can remove the fuse which should shut it off but I'm wondering whether the real problem lies with the rear winder defroster relay in the power distribution center. Thanks.
 
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This might be like killing cockroaches with a bazooka, but they sell a "battery disconnect" that you can flip after you park your jeep. Prevents easy theft, too! Not the last word in convienience, tho.

If you don't want to tear the Jeep apart, and you know what fuse kills the problem, maybe put a switch in there right next to the panel, only for that switch?

Good luck, and keep on Jeepin'!
 
Could be by design. It will keep your hands warm while you are pushing the Jeep.:D

Sorry, cheap car joke.
 
Pulled the fuse and that shut off the defroster so now at least the battery won't be drained. Cannot find the relay fuse. It's not in the power distribution center where it's supposed to be. I'll tackle it later when it warms up, only use the rear defroster very occassionally anyway. Thanks guys.
 
Hey Archie I work at a dealer I might be able to help. I'll need more info to start. What year and model? If it's newer than say 98 I can access info at home. Let you know how its setup,locations ect. Good luck
 
MOPAR3 said:
Hey Archie I work at a dealer I might be able to help. I'll need more info to start. What year and model? If it's newer than say 98 I can access info at home. Let you know how its setup,locations ect. Good luck
Click to expand...

Thank you MOPAR3. It's a 1997 Grand Cherokee Limited. Fusebox is on the botom of the passenger's sidewall, power distribution center is located just behind the battery. Fuse is 10 amp, red, in #10 cavity. I pulled it. Relay is 40 amp, orange and supposed to be in #19 cavity in the power distribution center, but I don't see it.
 
Okay PDC has a 40amp fuse that feeds the relay that is located in the JB (junction block) the 40amp fuse supplies the coil and the switched power at the relay. The relay is grounded by the body controller. The relay also feeds power back to the switch through the fuse in the junction to light up the switch. The switch is a momentary contact switch that tells the BCM to ground the relay coil. Its possible that the switch,or the switch circuit is shorted telling the BCM to turn on the relay. You'll need the scan tool to check the inputs to the BCM or you could check the wire at the BCM for resistance to ground with the switch plugged in then disconnect it to see if the circuit opens. Also more likely the relay contacts are welded together. The relay is a standard ISO relay so you could swap it w/any other relay you have handy. Make sure you use a mopar replacment as they usually have a diode across the contacts to contain any EMF when the circuits turn off. The relay is closest to fuse 1 in the junction block. You may have to remove the kick panel to see it try pulling it and swapping with a known good one. If that doesn't work then its time to dig deeper.
 
Is the junction block the same as the power distribution center, located just to the rear of the battery? Or is it the fuse box located on the passenger side panel (kick panel?). Because I'm showing a 40 amp fuse in the power center and a 10 amp fuse in the fuse box inside the Jeep. Just so I know which box is which.
 
The PDC is under the hood near the battery. The junction block is the fuse block in the kick panel. Sorry about the confusion.
 
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