Another Rear Defrost Question

blonde1boarder

blonde1boarder

New member
Hey Guys. I've got a 97 SR5 and the rear defrost isn't working and the light does not turn on. I made sure the window is all the way up and even checked the limit switch to make sure that the window was up. Fuse is good, double checked. Rear wiper works also. I do have continuity across all of the wires on the window so my next thought is that maybe the switch is broken or that the relay is broken. Where is the relay located on the 97 4runner and how would I go about checking the switch? I have the FSM for the 2002 and my engine fuse box doesn't have the DEFOG relay so I have no idea where it is. Thanks for any help.
 
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Does the rear window go down? The rear defroster and window and such are all tied together.

Once, my rear window wouldn't go down, and I turned on the rear defrost for a second to "send some power back there" and it worked! Other than that, that's all I know...

Hope you get a fix soon!
 
Ya the window works with the switch and the key, the wiper works but the defrost doesn't work. I checked out my Chilton manual but can't find anything on the location of the relay.

If the light doesn't turn on for the rear defrost, on the center panel does that mean that the defrost switch is broken? How would I check if that was broken?
 
I'm still dealing with this problem. Maybe there isn't a relay? The 2002 FSM says that the relay is located in the engine bay fuse box on the drivers side. Maybe the relay is stuffed underneath or something? Any help locating on a 97 6 cyl would be helpful.
 
Potentially answered my own problem to help other people out. I got a hold of the circuit diagram for the 1997 defogger circuit and the relay is located in junction box 1. This is the same box that the 10A gauge fuse box is located. I haven't located the actual fuse yet but now I have somewhere to look.
 
+1 even I got the same issue, add to it my rear washer also does not works.

No light on the switch, is the switch broken or its something else?
 
I did some searches on this subject and apparently it's a common problem, but we all know Toyotas are perfect in every way and can't have a design flaw right?
Now I sound like a Honda owner. OK, I found this schematic

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/053rwdmh.pdf

I stole that from an old post the [MENTION=10169]TheDurk[/MENTION], but I don't know if it will help you if your not experienced solving this type of thing. It seems a lot of people have issues with the harness going in and out of the rear gate. Better do some searches of your own for more ideas on where to look. I did find that the light on the switch is a separate fuse, so check all that too.

I bought my 4runner in August of this year and the seller told me he took the relay out because it was blowing fuses. He even gave me the relay. I wasn't worried about it, we really don't need it here in Southern California. But now that I see how many people have trouble with it, I'm going to solve mine and start a thread. Won't happen in the next couple of weeks though, too much life and never enough time!
 
I should have read that diagram before attaching it, you didn't mention having heated mirrors and the diagram is for an 02. Mine is a 2000 but also doesn't have heated mirrors. This IS California. Now I want to make time to figure this out!
 
I found a simpler diagram, sort of generic but I think it's a little easier for everyone to understand. Ultimately if you get familiar enough with how the system works, it's easy to track down the problem. This diagram doesn't show the window up cut out switch, but remember that it is there and must be closed for the defroster to operate.

http://www.autoshop101.com/forms/ToyEWB.pdf

This is a pdf file and has a lot of different circuits. The Defroster is in section A1 page 5, about half way through the file.
 
My defrost isnt working but the light does turn on...i removed the access cover on the back hatch to find that the little wires that go on the corner of the window were just dangling there...i guess 13 years of the window being rolled up and down they fell off....now i just gotta figure out what i need to get to re-attach them.
 
IBallEngineer said:
I found a simpler diagram, sort of generic but I think it's a little easier for everyone to understand. Ultimately if you get familiar enough with how the system works, it's easy to track down the problem. This diagram doesn't show the window up cut out switch, but remember that it is there and must be closed for the defroster to operate.

http://www.autoshop101.com/forms/ToyEWB.pdf

This is a pdf file and has a lot of different circuits. The Defroster is in section A1 page 5, about half way through the file.
Click to expand...

Thanks a ton for digging out the details man. I am not so blessed to understand all these diagrams, still will try my best. Hope you crack the issue soon! :thumb3:
 
Tdaz250 said:
My defrost isnt working but the light does turn on...i removed the access cover on the back hatch to find that the little wires that go on the corner of the window were just dangling there...i guess 13 years of the window being rolled up and down they fell off....now i just gotta figure out what i need to get to re-attach them.
Click to expand...

If the tabs the should be bonded to the glass have fallen off, you can buy a special glue to re-attach them at most auto parts!:guitar2:
 
cyclops13 said:
Thanks a ton for digging out the details man. I am not so blessed to understand all these diagrams, still will try my best. Hope you crack the issue soon! :thumb3:
Click to expand...

OK, so I had a friend pull the schematic for my truck, 2000 not a limited. It was essentially the same as the FIRST link I posted. The Body ECU, next to the underdash fuse block is what actually grounds the relay in the engine bay, or wherever it is in your year truck. There is also a Back Door ECU, in the rear gate. It has 5 wires
Pwr
Ground
Limit switch
ECU
MPX
I'm not sure what the last two do, or how they do it. They might send serial data to the Body ECU, or simple voltage, or ground. In any case I'm sure this communication has to happen for the Body ECU to ground the relay, and the light in the switch.
By the way if you don't have heated mirrors, just ignore that part of the diagram. Also the two wires between the Body and Back door ECU's go through THREE connectors, they are identified in the link. I sure wish I had time to follow this up, it's fun!
 
Anybody with these kinds of problems should inspect the wires in the harness by the liftgate hinge that connects to the body. After 11 to 17 years of flexing, these wires can break or lose their insulation and short.

The MPX wire is a comm link between the Backdoor ECU in the liftgate and the Body ECU by the driver's knee. It affects a number of systems including wireless door locks, rear window and wiper operation, etc. It goes through that harness.

I just have no idea if a '97 has this design, but my '99 does as do more recent 3G trucks.
 
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