Rear Defrost Fuse keep blowing

[MartyP]

This just happened, when I press the defrost switch to turn i on, the fuse mlt instantly.

Anybody what could cause this ?

It was working before and I didn't chang anything !!!!

Thanks !

[Michael]

Try lookinhg in your cig. lighter and see if a penny found it's way in there.

[MartyP]

No penny there !

Anyone knows why ?

A ground somewhere ?

Could it be because My mirror switch is unplugged cause this fuse is for the mirrror switch and the defrost.

[guss23]

Did you recently remove the window switches? I accedently plugged my window plug into my defrost switch once and that happened.

[Michael]

The penny idea was a shot in the dark, may not even be on the same fuse.

You definately have something grounding out hard to instantly pop a fuse for a defroster. Things like this usually don't happen without a little help. I bet if you think baxk you could remember the last few places you were working on the car which may lead you to something that got wired up wrong in a recent repair, or you pinched a wire with a screw. If not then just start at the switch and work forward, I like to test all components before tracing wires, and the switch is the pefrect place to start. It may be as simple as a contact becoming loose inside the switch.

[Farrar]

Try pulling the green "relay" which is the timer for the rear defogger. Hit the switch again. If the fuse pops, your problem is between the switch and the relay compartment. Should make tracking down the wiring fault a tad easier/quicker.

Good luck!

[congerz83]

I think the real story here is that his defroster ever worked in the first place.:giggle:

[thirdmanj]

I think the real story here is that his defroster ever worked in the first place.:giggle:

:lol: that's what I was thinking. The question I have: Is the rear defroster even nessary? Its pretty well sheltered and besides, doesn't all the heat put off by the engine make the defroster kind of redundant?

[jawn101]

:lol: that's what I was thinking. The question I have: Is the rear defroster even nessary? Its pretty well sheltered and besides, doesn't all the heat put off by the engine make the defroster kind of redundant?

I think it's similar to the windows/locks in that a luxury car in this era was expected to have certain amenties, whether they really made real world sense or not.

In other news, my rear defroster works - but I had to use an IR thermometer to figure that out :) Even leaving the D outside overnight didn't generate any condensation on that window that didn't vanish the minute I cranked the motor.

[dmc6960]

A method to defog the rear quarter glass would be much better for practicality. I've driven in the full range of weather conditions available, and the rear quarter glass gets blocked by condensation 1000x more than any fogging/frosting on the rear window. Its a shame such a process would be very difficult to make work effectively.

[MartyP]

I know I dont need it, but it was working before, at least the light came up when I pressed the switch. Now I have nothing !

Thanks Farrar, I'll try it wthout the the relay !

Yes,I removed the the window switch, but these work fine so No, I didnt put it back on the wrong connector.
I was working in the center console, so I'll check that out !


Thanks !

[jawn101]

I was working in the center console, so I'll check that out !


Thanks !

Definitely look for a pinched wire or a cut in the harness where the console bolts down. Easy to do by accident and can be catastrophic if something carrying high current grounds out.

[Farrar]

I keep a shower squeegee and microfiber in the car and wipe the windows down while during warm-up.

Edit: Oops, I forgot the quote. Anyway, the above remark was addressed to the guy who was complaining about the RQP glass fogging up. Also, you can warm the engine with the cover open. That way more heat will hit those panels.

[MartyP]

So I've put a new fuse in and its actually when I turn the key ON, the fuse blows, not ven when I press the rear defrost or move the mirror.

It's Fuse #9.

I tried without the green relay, same thing. The fuse melt when I turn the key.

winter is finished here and I'm getting ready to take out the car in 2-3 weeks.

Thanks !

[jawn101]

Almost definitely a short in the harness then. That circuit is simple as can be - power to fuse to switch to relay to screen (and switch to lamp as well). Have you taken the console back out to see if you nicked anything?

[Farrar]

The power mirrors are also on Fuse #9. Have you done any work in the doors recently?

[MartyP]

Yes I did replace the window motor, so I'll have to check the driver door and the console !

I'll remove the console tomorow and check it out !
Thanks, I just wanted to know where to concentrate my research !