rear defroster not working

[irowiki]

Turn the switch on, defroster idiot light comes on, no increased electric load.

Checked defrost circuit breaker, it works. 12 volts to one leg of the CB.

Disconnected both wires at the rear glass, no voltage to either wire with the key on and defroster switch on.

Checked connectors on glass with ohmmeter, .03 or something, so at least some lines are intact.

FSM references a defroster relay, where is this? Drivers side fuse panel didn't have it, not did the engine fuse panel.

[Petros]

it is probably behind the kick panel above the passengers feet area. if you remove the glove box you can see a small panel with electrical components on the right side next to the heater blower motor. there are several relays there, one is for the starter, and several others for other systems, it is likely one of these.

[dlb]

peter is right, the rear defroster relay is behind the passenger side kick panel. check page 657 (BE-7) in the FSM for a pic.

[marlinh]

The wiring for everything that goes to the rear of the vehicle travels along the passenger side of the car. I have found broken wires in the flex tube at the top of the door before. Also, the connector for the rear hatch is under the side panel below the right rear tail light. You could check if you are getting power there. I have seen problems there too but it is usually due to rusted out rear quarter panels and moisture getting in. You shouldn't have that problem.

[irowiki]

Peter / David: thanks, my 1st gen only has the fuse panel, driver's kick panel and engine fuses! I was looking for exactly that sort of picture, but couldn't figure out where it was in the FSM. The rear defogger part of "body electrical" will also be very useful!

Marlene: ah ha! I was thinking I needed to take the entire panel apart to find the connector, thank you!

[marlinh]

I have a factory electrical manual I photocopied from the dealer. It gives all the locations of connectors etc. It is more detailed than the wiring diagram in the FSM. If you have any specific questions maybe I can help. The manual is for an 86, but most of it is the same for other years.

[irowiki]

Okay, I'll let you know!

I just printed out the wiring diagrams from the FSM and taped them together to try and sort out a few wiring messes.

[Petros]

another important place to look is where the wire bundle passes from the body to the door itself. It is always flexing there and eventually the wire itself can fatigue and break inside the insulation so you can not see it by inspecting the wires. If you have power at the connector, but no power at the contact on the defroster, you two sewing type push pins and stab the wire and check for continuity. try it on either side of the bend where it passes from body to door first, this will help you isolate it if indeed it is an internal break in the wire.

[marlinh]

Did you figure out your defrost problem yet?

[irowiki]

No, was preoccupied this weekend getting the rust out of Pokey's cooling system and getting good stuff back in. I was just pondering it last night, because it is bugging me!

It's on the list of things to do which includes but isn't limited to replacing the carb on the sedan and hooking up all the vacuum emissions systems (ugh), tilling up all the garden areas, planting a bunch of tulips, get the house heater working, find out why the fast idle on the wagon isn't working, install external AT cooler and remove towing stuff from the wagon, clean SR5 seats and install, install a bunch of trim pieces in the sedan, and of course try and fix the defroster!



Somewhat on topic though, before picture of rear window. The clear film came off, leaving the tint gunk which was dryrotted and only flaked off.



After a lot of scraping by myself and the wife, here's the result:



Not sure how to get it off the wires themselves, ideas?

[marlinh]

None, those wires are delicate. Patience with a razor blade perhaps?

[dlb]

jeez, i'm not sure what you can do there. when i removed tint, i used a hair dryer to heat the tint glue up a lot and peel it off slowly in large chunks. after that, i just had to rub all the remaining glue residue off using my fingers. it never flaked off.

i guess if i were you, i would just use my fingers to carefully work all the tint and glue off, if that's possible. good luck, paul.

[irowiki]

This stuff was weird, I heated it up good with the hair dryer, and the film came off leaving the tint crap behind. The top right of the before picture was apparently done before the tint crap had a chance to dry rot, it was clean!

I'm hoping if the defroster actually works, the heat from that might help me!

At this point I'm wondering if I should just source new rear glass, is it a pain to replace? Better to do the whole hatch?

[marlinh]

According to the manual, the glass pops out of the seal. I think Petros has experience with these. The chances of having a leak afterwards is always a possibility I guess. I guess it depends on what you can find. If you are coming up my way, I am getting two cars towed away soon. I have one rotten hatch with excellent glass.

[irowiki]

Unfortunately I'm not going up there anytime soon, most likely. If I was I'd totally snag your A/T and the rear glass! I can imagine freight shipping from canada to the US is probably way too much.

I've been part searching and apparently there was a "Standard" defroster and a "heavy duty" defroster.