Rear defroster won't work need diagnosing assistance (Toyota Camry)

[steppinthrax]

I have a 99 Camry LE. I noticed when it started getting cold the rear defroster didn?t work. I would push the button and it would light (indicator), but I can tell it doesn?t work. I have the Factory Service Manual. I went though the diagnostics but the only thing it leads me is something is wrong with the wiring from the relay (switch side) to the actual defroster coil.

I?ve done the following

1. Tested the switch (works)
2. Tested the relay (works clicks when switch pushed)
3. Pulled off molding on rear window and checked coil. Coil shows resistance and works, no damaged lines.

The I pulled off the wires that run to the defroster coil. I?m getting no voltage to the defroster coil. Which tells me something is wrong with the wiring that leads to the defroster coil.

Does anyone know any other ideas?

 

[exdeath]

Just hearing the relay click isn't enough, there could be a problem with the contacts even though the armature still moves.

You need to test it with a meter or simply pull out the relay and bypass it by temporarily shunting the appropriate pins with wire and see if you get power at the defroster connector (use heavy gauge wire for high current stuff like heating elements). Similar to the paperclip in the ATX connector to test a power supply.

Also check fuses?

 

[boomerang]

You've basically got it figured out. The relay clicks so it's getting energized by the switch. With it energized, probe the B+ lead at the relay to make sure there's current there. Then check the lead that runs back to the defroster. If you have current there, the problem lies between the relay and the rear defroster.

If there is no current at the B+, check the fuse (probably a circuit breaker actually).

When operating normally, will the defroster run as long as the key is on, or does it have a timer? The timer may be faulty and will not allow the circuit to be energized at all. The timer could be integrated into the relay, or be part of the switch or could be a separate entity.

I'm assuming the manual has wiring diagrams. You've got the smarts you need to figure this out if you've gotten this far.

 

[steppinthrax]

Originally posted by: exdeath
Just hearing the relay click isn't enough, there could be a problem with the contacts even though the armature still moves.

You need to test it with a meter or simply pull out the relay and bypass it by temporarily shunting the appropriate pins with wire and see if you get power at the defroster connector (use heavy gauge wire for high current stuff like heating elements). Similar to the paperclip in the ATX connector to test a power supply.

Also check fuses?

I actually took the relay out and I put in on a 12 volt power supply. I had the cover off the relay and I energized it. The relay snapped and I could see it move. I measured the resistance across the switch portion of the relay and it was definalty working. The problem is the relay for the defroster circuit is not really that accesable. It's in an area of the car under the dashboard where you have to almost feel around to pull it.