rear defroster not working, even with power too it?

[thegipper]

So I noticed that my rear window defroster hasn't been working. The light does turn on when I push the button in.

The next thing I checked was the fuse, fuse is fine.

Then I decided to pull off the back panel and take a look. Both the connectors are connect and intact. I put my volt meter on the two wires and I got 12v.

Last but not least, I checked for any missing spots on the wire throughout the glass, I couldn't find any breaks or anything.

So, why the hell isn't it working? This one has me stumped....

:noidea:

 

[Magmotor]

Here's the troubleshooting guide for the defogger. Recheck your wires, i'm pretty sure just because you have 12v where you measured doesn't mean the wires are good....hope this helps..luck with it......

http://tacoma.site40.net/4Runner_96...ypdf/02rmsour/2002/024runne/be/defsy/insp.pdf

 

[kball]

Maybe with the door open the wires made connection while you were checking the connector. With the door closed they don't make connection..? Check the wire harness in the loom at the top.

 

[thegipper]

I had the defogger on with the hatch up with power to it for a good ten or fifteen minutes but the grid never got warm at all. I thought for sure I wasn't getting power to those wires and the cause was probably a broken wire in the loom but doesn't appear to be the case.

I will check the pdf and see what else it could be.

 

[19963.4lsr5]

With the wires removed from the grid read the ohms between the two tabs.


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[thegipper]

With the wires removed from the grid read the ohms between the two tabs.


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What should it be?

 

[19963.4lsr5]

Read it and report


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[thegipper]

10-4

 

[TheDurk]

What should it be?

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/be/defsy/insp.pdf

 

[19963.4lsr5]

10-4

Report the ohms. It should be real low. Like between 1 and 3 ohms. It defiantly shouldn't be open or higher than 20 ohms or it won't make enough amps to heat the glass.


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[SaulG]

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/be/defsy/insp.pdf

This is the way to do it quick ! Check tabs on window as they rot apart sometimes and the 0v or ground wire side .

 

[thegipper]

Well I forgot to check the ohms but I did check each wire using the method in the FSM. Every wire was about 5v so apparently there aren't any breaks in the wire either.

I turned it on the other day and noticed it kind of, sort of, started to melt some frozen condensation on the back window. It appears that it is "working" but working poorly. Every other vehicle I've owned does a much better job. Not sure if the ones on these trucks just suck or if mine "works" but isn't working as good as it should.

I'll check the ohms soon and report back.

 

[JARO]

Check wire loom hooked right under glass, in my truck wires was cracked in this place.

 

[thegipper]

I'll check that too and also the connections, maybe they are corroded and not making good contact. I'm assuming if they were cracked, I wouldn't get any power at all but who knows.

 

[TheDurk]

I'll check that too and also the connections, maybe they are corroded and not making good contact. I'm assuming if they were cracked, I wouldn't get any power at all but who knows.

Quite often bad connections or almost broken wires can show voltage but not pass current. That's why I prefer a test light with a decent sized bulb that draws real current for this kind of troubleshooting. For this issue, I might even make one special using a 55W headlight bulb. Takes about two minutes if you have the bulb.

 

[19963.4lsr5]

Quite often bad connections or almost broken wires can show voltage but not pass current. That's why I prefer a test light with a decent sized bulb that draws real current for this kind of troubleshooting. For this issue, I might even make one special using a 55W headlight bulb. Takes about two minutes if you have the bulb.

+100. My test light uses a bright dome light bulb.


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