rear window defroster
12-02-11, 07:29 AM
#1
Driver School Candidate
Thread Starter
rear window defroster
I searched for this topic but did not find anything, perhaps it is labeled something else. If the topic has already been beaten to death, sorry for the repost... please point me to the thread.
My rear window defroster (2002) was working great, and all of a sudden just stopped. (right when it starts to get cold)
By the way, the side mirrors (activated by the same button) are still heating although I think they are fused on a separate circuit. I checked the fuse in the trunk (30A) but it is good. Has anyone had this problem, and if so, how did you end up repairing it. I know the stealership will probably charge an arm and a leg but I also realize if the window needs to be completely replaced, I'm not skilled enough to DIY. Is there anyway to determine if the element itself has died? I do have electrical skills and have a digital voltmeter if resistance or voltage measurements are involved.
In any case, thanks for any assistance you can offer, this forum is an awesome resource.
My rear window defroster (2002) was working great, and all of a sudden just stopped. (right when it starts to get cold)
By the way, the side mirrors (activated by the same button) are still heating although I think they are fused on a separate circuit. I checked the fuse in the trunk (30A) but it is good. Has anyone had this problem, and if so, how did you end up repairing it. I know the stealership will probably charge an arm and a leg but I also realize if the window needs to be completely replaced, I'm not skilled enough to DIY. Is there anyway to determine if the element itself has died? I do have electrical skills and have a digital voltmeter if resistance or voltage measurements are involved. In any case, thanks for any assistance you can offer, this forum is an awesome resource.
Last edited by DrawDog; 12-02-11 at 07:30 AM. Reason: mis
12-02-11, 05:44 PM
#2
Moderator
We'll need to go through some diagnostics to see if we can narrow down the problem(s)...
The first is obvious, carefully inspect the rear window defroster, looking for any broken wire on the glass and at the connector. I know you said you did this, but humor me....
Next, let's test the switch on the A/C panel, with the ignition switch in the ON position, depress the defroster button and put your hand on the outside rear view mirror... Is it getting warm, if so the switch is good., if not the switch has gone bad and the whole assembly has to be replaced...(expensive)
Next, pull the fuse again and get out your volt/Ohm meter and check it for continuity. If it's good, put it back.
That narrows it to the relay for the defogger relay and wiring harnesses. UNFORTUNATELY to get to the relay, you'll probably have to take the trunk garnish apart... It's In the same junction box directly below the fuses...(see the diagram below) and there's a good possibility it's the relay BUT the carpet garnish covers it and restricts access to it. The rear window connectors, R13 and R14, are on the drivers side and under the roof garnish. While it's not difficult getting the garnish piece off, it's a pain the *** to get back in place with all the clips correctly in place. Carefully pull it off and check the wire continuity on the glass with the V/O meter.
Good luck and let us know how it turns out.
The first is obvious, carefully inspect the rear window defroster, looking for any broken wire on the glass and at the connector. I know you said you did this, but humor me....
Next, let's test the switch on the A/C panel, with the ignition switch in the ON position, depress the defroster button and put your hand on the outside rear view mirror... Is it getting warm, if so the switch is good., if not the switch has gone bad and the whole assembly has to be replaced...(expensive)
Next, pull the fuse again and get out your volt/Ohm meter and check it for continuity. If it's good, put it back.
That narrows it to the relay for the defogger relay and wiring harnesses. UNFORTUNATELY to get to the relay, you'll probably have to take the trunk garnish apart... It's In the same junction box directly below the fuses...(see the diagram below) and there's a good possibility it's the relay BUT the carpet garnish covers it and restricts access to it. The rear window connectors, R13 and R14, are on the drivers side and under the roof garnish. While it's not difficult getting the garnish piece off, it's a pain the *** to get back in place with all the clips correctly in place. Carefully pull it off and check the wire continuity on the glass with the V/O meter.
Good luck and let us know how it turns out.
Last edited by VVTiBob; 12-03-11 at 01:08 PM.
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prech (01-10-20)
12-03-11, 07:15 AM
#4
Lead Lap
Our rear view mirrors have defrosters? (Sounds like another entry for the thread discussing features we didn't know about for me...)
12-05-11, 07:41 AM
#6
Driver School Candidate
Thread Starter
Update: The switch not only lights up, but both outside rearview mirrors get warm, and the fuse itself is indeed continuous. I could not see any breaks in the heating element on the window itself so it looks like I'm going to have to dig around in the trunk this weekend.
Bob, by your description, I assume the fuse box is electrically "pre-relay" and thus there is no way to check the continuity of the heating element from there. OBTW, thanks for the excellent description/images.
Bob, by your description, I assume the fuse box is electrically "pre-relay" and thus there is no way to check the continuity of the heating element from there. OBTW, thanks for the excellent description/images.
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Ghiggs662 (12-04-20)
09-23-12, 02:15 PM
#9
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Location: South Carolina
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Haven't had any frost yet here in SC, but on mornings when the rear window is foggy, turning on the defogger only clears a small part of the window. Does this most likely mean the wire has been broken?
12-09-13, 02:16 PM
#10
I just posted the following in the ES350 Forum but I am hoping that VVTiBob can help me out.
My rear window defogger did not defog this morning. I tried to check the 50 amp fuse but it is under a long narrow cover that I found very hard and cumbersome to remove. Does someone have a suggestion as to how to accomplish this?
I did see in another post regarding a 2002 model (that was the year the poster quoted) where the responder said to 1) check that the wires on the glass are not broken (mine are not broken) and then check if the outside rear view mirrors get warm to see if the switch is OK (my outside mirrors do get warm).
Where I am confused is the responder then said to use a meter to check the fuse for continuity and if the fuse is good then he/she said it narrows it down to the "relay for the defogger relay and wiring harnesses". But what I don't understand is that if the outside mirrors get hot then doesn't this automatically mean the fuse is OK?
Any help would be appreciated.
My rear window defogger did not defog this morning. I tried to check the 50 amp fuse but it is under a long narrow cover that I found very hard and cumbersome to remove. Does someone have a suggestion as to how to accomplish this?
I did see in another post regarding a 2002 model (that was the year the poster quoted) where the responder said to 1) check that the wires on the glass are not broken (mine are not broken) and then check if the outside rear view mirrors get warm to see if the switch is OK (my outside mirrors do get warm).
Where I am confused is the responder then said to use a meter to check the fuse for continuity and if the fuse is good then he/she said it narrows it down to the "relay for the defogger relay and wiring harnesses". But what I don't understand is that if the outside mirrors get hot then doesn't this automatically mean the fuse is OK?
Any help would be appreciated.
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