Rear defroster not working

[aclos3]

Hi guys,

I've got an issue with my rear defroster barely working. I only get marginal defrosting occurring on the middle line that goes across the rear window. This "middle line" is the one nearest to where the power connects to the defroster. The wide band of conductive material near the power terminals appears corroded or "rusted." Its not chipped off in the manner that would normally cause a few lines to stop working, but rather it appears that barely any power can move through the corroded material to any of the lines that go across the window.

With ski season practically on top of me I, I'd like to get this fixed soon, but I'm wondering what to do. Is there something I can do on my own, or would it be better for me to have the whole "pattern" completely reapplied? What type of place usually does this kind of work if I can't do it on my own? A window tinting shop maybe?

Thanks!

 

[aclos3]

I should add that I bought a repair kit, but it seemed designed to only fix the type of rear defroster problem caused by a complete break somewhere in one of the lines. I returned the kit because it looked like all of my traces were fine and that I'd either need a lot more conductive material (to replace the wide areas near where the power comes in) than what came with the kit or I'd need to go to a professional.

 

[S.CarolinaFZJ80]

Same problem. All of my conductors are intact aswell but it only defrosts a small area in the center of the rear window. The connections are tight too. Wonder if the defrost unit is getting enough power. My windows are slow too, I wonder if the two problems are somehow related???

 

[arndog123]

The rear defrost is the same way in my '97 and it's a little annoying. The one on my LX works great and clears the window up really quick.

 

[aktundra]

guess I should not complain, (mine seems to work fine) but does anybody know if the rear defrost should have an auto shut-off after a certain point ?

 

[arndog123]

It doesn't seem like it. My '96 and '97 stay on 'til I push the button off even after pulling the key out.

 

[SpillmanCruiser]

same problem here. I'm planning on tinkering with it tonight, so I'll let you know what I come up with.

 

[aclos3]

Thanks for the response... looks like I'm not alone. My windows are also a bit slow, but I don't think it is related. It seems slow windows are usually a symptom of excess friction with the window runs, and not low voltage. I hadn't considered the possibility of insufficient power causing my weak defroster, but there may be something to that.

 

[SpillmanCruiser]

You need the FSM to fix this

"I should add that I bought a repair kit, but it seemed designed to only fix the type of rear defroster problem caused by a complete break somewhere in one of the lines. I returned the kit because it looked like all of my traces were fine and that I'd either need a lot more conductive material (to replace the wide areas near where the power comes in) than what came with the kit or I'd need to go to a professional."



Ok, finally got around to looking at this. Most likely your wires running along the glass have been broken. I think I broke mine by loading crap too high that hit the rear window. It is very hard to see the breaks. They are not always visible, hence the test below.

You will need to test the rear defrost per the FSM. This involves a volt meter and piece of aluminum foil. You hook up the (+) probe of the meter to the DS plug, i.e. the positive end of the system is on the driver's side in my 1997. Wrap the aluminum foil around the tip of the (-) probe and run it along each of the horizontal wires. If you follow the FSM, you can easily find where the wire is broken. It is a bit complicated for me to explain from memory, but not too hard for this 1-. I just marked the broken wires with a Sharpie for later repair.

I was able to find a defroster repair kit at pep boys for about $12. One day this weekend I will get around to using it, erase my sharpie marks and post results.

 

[Stefangoalie]

I have huge issues with my rear defroster and all my back windows. I cannot keep them defrosted, so my view is almost always limited to the front 2 windows! A bit dangerous for the little compacts that go unnoticed. Its one of the few things I HATE about my cruiser (my visor is also an enemy).

 

[S.CarolinaFZJ80]

Thanks. I'll have to check the rear defroster. As for the windows being slow...I opened up my driver side; removed window, cleaned rubber tracks with towel & silicon lubricant spray (on all the areas that I could easily reach). Wow, there was alot of stuff in there. I also removed regulator, cleaned teeth & tracks, re-lubed with lithium grease.
Motor worked fine when out, smooth and responsive. However, when everything was bolted back together the improvement was only slightly better. I think the rubber in the window tracks is too tight. When I replace speakers I will remove rubber and throughly clean. Hopefully that will work!

 

[SpillmanCruiser]

Tried to repair the defrost this weekend by NOT following the instructions on this kit: http://www.permatex.com/products/Au..._Complete_Rear_Window_Defogger_Repair_Kit.htm

I used masking tape instead of the template provided. Anyway, I called Permatex and they offered to send me an entire new kit even though I screwed up! Pretty good service if you ask me. Will fix the damn defrost according to instructions and let you guys know if it works. Too bad I won't have it for my ski trip.

 

[haffi]

On the wire harness inside the upper rear hatch, are three plugs. These plugs are often corroded and bad connectors.

On my 80 I had several problems with the wiper, rear domelight and the defogger until I removed these plugs and soldired the wires together.

I´m actually working this problem on one truck right now but I dont have a camera to show you what I mean.

 

[haffi]

This is one of the plugs I removed from the rear hatch. This one is located in the driver side of the rear hatch. HIdden behind the rear viper control box.

As you can see there is rust inside the connector. There is no power (ground) going through the white/black wire. This was causing the failure in the viper and the defogger.

There is another plug next to this one, with six wires. I also removed that one.

 

[Ghetto FJ]

Do you have any pics of all the wires soldered together? My rear defroster and wiper and both inoperable right now. This is probably why!

 

[haffi]

No, this is the only pic I have. Sorry.

 

[12112321AKYLE]

guess I should not complain, (mine seems to work fine) but does anybody know if the rear defrost should have an auto shut-off after a certain point ?

Yeah it shuts off after a few minutes (at least on mine) but I'm only getting the middle line working as well. I'm up in Fairbanks so this is an important issue for me too.

 

[BTLSHP]

Help,

I have been trying to diagnose and figure out how to repair a non-functional rear defroster. I think the switch and relay are ok. The switch lights and I hear the relay click. I am reluctant to start pulling apart plastic as it is 30 degrees out and the multimeter I borrowed seems to b pointing elsewhere. At present, there is zero hint of a functioning defroster.

Using the FSM, I turned the ignition on to position II and traced voltages with the positive lead on the driver's side tab and foil on the negative. At the center of the glass the lowest two wires returned 9-9.5 volts, the rest were between 6.2-6.8 volts. All of them moved smoothly down to around 0.1-.2 volts at the driver's side edge. Even the vertical conductor band on the driver's side edge returned a non-zero value.

This all left me confused. I then shut down the car and did continuity tests after disconnecting the wires at the tabs at each side. Here is where I ran into an issue. Individual "wires" all have continuity using foil on both leads, so too did the vertical connecting paint/film. But with the probes positioned as in the image below there was only a momentary beep and silence (same at any spot on the brown strip). Putting both leads on the tab produces a strong steady tone. So, it seems to me the "tab" for the wire has become isolated from the wire grid. Is this possible? Corrosion? What is the fix?

Thanks,

Doug