2000 Rear Window Defrost Problem

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ultimatt

New member
Have a 2000 Limited 4x4 with a defrost problem. The switch on the dash lights up and the side view mirrors defrost as they should. However, the rear window has no defrost action whatsoever. The grid on the window checks out with no nicks, scratches, or missing material.

Any known issues with the wiring harness that would cause this problem. Just thought I would ask before tearing into the hatch...thanks.
 
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I've noticed the defrosting of the mirrors is significantly faster than that of the rear window. How long are you allowing for the rear window to defrost? Also, I believe the defroster switch has a timer on it and shuts off automatically.
 
Before surgery, I would try two things. First, make sure window is ALL the way up. I am pretty sure it has the same defeat link as the wipers to prevent operation except when 100% closed. Second, verify the fuse and relay in the engine bay. (The indicator light might be run off a dash circuit and just show that relay coil circuit is energized, while the load circuit is completely dead--probably is that way, as there is no good reason to route load wire through dash. Pull the relay if you don't believe me, I bet light still goes on.) If fuse is good, swap the Defog and Pwr Outlet relays and see what that does to each circuit. They are the same p/n relay (at least on a '99 w/o mirror defrost).

Only then would I open up the gate.(Actually, I would also verify coil and load 12+ at relay socket and load to ground resistance, but that's me).
 
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004Gunner said:
I've noticed the defrosting of the mirrors is significantly faster than that of the rear window. How long are you allowing for the rear window to defrost? Also, I believe the defroster switch has a timer on it and shuts off automatically.
Click to expand...

The rear does not defrost at all - the heat in the car eventually does the job...takes 15 minutes or more...
 
Ok, you got me curious. I pulled up the ncttorra wiring manual. They DO run off the same relay, but that relay powers SEPARATE FUSES for the mirror and rear window defoggers. Mirror is a 10A in the Engine Relay/Fuse Box and the Rear Window Defog is a 15A just above it. The window limit switch IS a part of the circuit. The indicator light runs off the GAUGE circuit.

So first, check the RW DEFOG fuse. I prefer a swap with a known good fuse; don't just look at it and put it back. Then roll the window down and put it 100% up. Then take your VOM to the window resistance striping. Toyota FSM says wrap the test leads in aluminum foil to get a reading. Assuming that is zero, then it is time to break open the gate.

I'd check that limit switch, the connections to each side of the grid, and the incoming power and ground to the circuit. Here's your wire diagram:

Defog Wire Diagram

Happy hunting!
 
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Not to drag up a thread that is over a year old, but did anyone ever hear what the resolution was to this problem? Mine has the exact same problem.
 
rear defrost

Have 1999 4Runner. Slammed the rear hatch and the rear defrost didn't work. No fuses blown, side mirrors defrosted but took apart rear hatch and found connector gets brittle and broke off from window. It's a PIA to reattach. So if I was a betting man, I would say your attachmnet to the grid is broken easy to check PIA to fix Tom
 
airefuel, how did you re-attach your lead wire back to the grid on the back glass? I checked mine the other day, and one of the wires had come loose. Thanks.
 
any success?

same issue here, how'd the fix go? I sure would lie it now that its winter haha, sucs not to see anything out the back.

Can someone describe where the connections are before I tear into it andthe smoothest way to check this. Thanks
 
I am lucky enough to have three lines work. one at the top and two at the bottom. so my dont do Sh1$. once dirty, it dont matter. lol
 
Truck 4Ever said:
same issue here, how'd the fix go? I sure would lie it now that its winter haha, sucs not to see anythin in the area, out the back.

Can someone describe where the connections are before I tear into it andthe smoothest way to check this. Thanks
Click to expand...

Turns out my problem was that the connections were disconnected at the rear window. I found some pieces of glass so I assume that the back window was replaced at some time and they did not hook the connections back up.

Check to see if your side view mirror defrost works, if it does the problem is at the rear window. Remove the cover on the hatch and you will be able to see the connections.
 
rear defrost, you don't miss it till you need it

Turns out my problem was that the connections were disconnected at the rear window. I found some pieces of glass so I assume that the back window was replaced at some time and they did not hook the connections back up.

Check to see if your side view mirror defrost works, if it does the problem is at the rear window. Remove the cover on the hatch and you will be able to see the connections.
Click to expand...

I have a 1997 SR5 no side defrost. It is quite possible that this is not the original rear window as well... I flipped opn the bottom of the liftgate with the window retracted a bit and through the smaller coutout facing the trunk space I could plainly see and tug on the 2 soldered connections. Is there a harness I should be able to see? I dont see one thats obvious at all.
Sure would like to get to the bottom of this haha
 
Maybe that could be improved

I just went back in there it was a while since I had seen it.
Both wires slide onto little metal tangs, they look good.
Tried the test light on the wires with the window up and defront light on, no light. Which one is the one that should have power, black or white?
Anyone know how to test where the problem might be?
I traced the wires bac to the little module on the other side of the window from the clips. Everything looks good, clipped some things in and out, no luck...
 
Same thing happened to me, window was broken a year and a half ago, got replaced (fo free!) and the window guy simply forgot to hook up the 2 connectors located in the top right (if looking at the truck from the back) part of the hatch.
 
rear defrost revival

TheDurk said:
Ok, you got me curious. I pulled up the ncttorra wiring manual. They DO run off the same relay, but that relay powers SEPARATE FUSES for the mirror and rear window defoggers. Mirror is a 10A in the Engine Relay/Fuse Box and the Rear Window Defog is a 15A just above it. The window limit switch IS a part of the circuit. The indicator light runs off the GAUGE circuit.

So first, check the RW DEFOG fuse. I prefer a swap with a known good fuse; don't just look at it and put it back. Then roll the window down and put it 100% up. Then take your VOM to the window resistance striping. Toyota FSM says wrap the test leads in aluminum foil to get a reading. Assuming that is zero, then it is time to break open the gate.

I'd check that limit switch, the connections to each side of the grid, and the incoming power and ground to the circuit. Here's your wire diagram:

Defog Wire Diagram

Happy hunting!
Click to expand...

I am doubting my rear defrost function... So if I turn my rear/side defroster on and use put my voltage reader leads on the little defroster strips on the window (with aluminum foil on the leads) it should read some voltage if it is working properly?
 
on my 2000 it was the cause of my parasitic draw, pulled the fuse and the relay and that solved it. but I never did bother repairing it:shocked:
 
baja1 said:
on my 2000 it was the cause of my parasitic draw, pulled the fuse and the relay and that solved it. but I never did bother repairing it:shocked:
Click to expand...

Yes my wife's 2000 will kill the battery in an hour if I leave the defog relay in. The problem is the Body ECU grounds it all the time. Some days I think I'll replace the Body ECU, then I remember, THIS IS CALIFORNIA.

:dance:
 
Mine doesn't work, so I checked the fuses today. The fuse was missing!
I counted the fuses and the previous owner put the 15a fuse in the empty slot (7th space from the top on the left column)
Hopefully it works when I try tomorrow!
 
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