KingCobraV9

iTrader: (2)

ok so the indicator light for the defroster stays on all the time at about half brightness, but if you turn the defroster on the light goes to full brightness. And the defroster doesnt work at all. If i pull the fuse the light turns off and if i pull the relay the light turns off but the defroster wont work.
any one have any insight on to what the problem may be? my first thought was a bad ground so i cleaned the ground the fsm says is for the defrost in the hatch but still no change. thanks!

CyberPitz

The sad thing, my NA has the same issue....I asked, and somebody said something about the relay, but I would think someone would have a more in depth view on it.

arghx

iTrader: (3)

turn the thing on and check for voltage on the actual defroster strips on the back window.

KingCobraV9

iTrader: (2)

i checked for voltage and i got nothing either way swich presed or not

freemanrx7

From my understanding the lines on the back hatch are part of the circuit. If any of the lines are cut then the defrost won't work. Not saying it's your problem but have you nicked any of the lines on the back window?

KingCobraV9

iTrader: (2)

well teh lines are teh grid that actually defrost the window and ya they all worked whaen teh defroster worked but like i said the light is on but nothing

KingCobraV9

iTrader: (2)

little update. i pulled teh relay out and the light turns off but if i press the swich not eh light turns on and off like normal. does ant one else thing the relay could be partly sticking?

BrettLinton7

iTrader: (33)

A friends does that same thing, but he doesn't care so...
and on mine, the light turns on and off, but it never defrosts.

So it looks like we're in the same boat. I'm subscribing to see if anyone gives a good answer

Icemark

Yeah, guys... if it doesn't defrost; it is probably disconnected.

Check at the rear defrost relay. You should have 12 volts+ on the White wire at all times. If it doesn't then the Defrost Circuit breaker needs to be reset.

The Black/Green wire should have 12+ volts on it, when the key is in the on position. If it doesn't, then you have a blown or missing 10A power steering fuse

There should be ground on the Black/White with the hatch closed and the key off. If it doesn't then the wires that plug into the window grid are unplugged.

There should be ground on the Black/Blue when the rear defrost switch is on and the key is on and the relay is unplugged. If there isn't, the defrost light should not be lighting up.

NoDOHC

Wow!

That just solved it for me, I have no power steering fuse due to a bad position sensor and that beep-beep-beep-beep-beep wearing me out.

I know that I didn't post the thread, but it intrigued me because I have the same issue.

That is awesome Icemark, you saved me a lot of troubleshooting!

Thanks!

Icemark

You should have just unpluged the power steering computer... You never want to pull a fuse, as the fuses all power other circuits, not just the one listed on the cover of the fuse box.

Most "electrical gremlins" actually sit behind the steering wheel when the car is on the road.

KingCobraV9

iTrader: (2)

humm i changed the ps fuse and it all works fine now. weird that the ps is tied into the defrost.
any ways what else is tied into that fuse? because i hooked up a bottle heater to a green/red wire the im gessing used to go the the power antena and that is what caused this problem to begin with.

the conector in question is a round rubber connector with a green/red wire and a red/somethin going into it
also why would the fuse popin cause the light to stay on all the time?

Icemark

The light comes on dim, because the circuit is being back fed.

And you hooked up a bottle heater to just what ever wires you found?



Most "electrical gremlins" actually sit behind the steering wheel when the car is on the road.

ASim1579

iTrader: (1)

I have a problem with my rear defroster, but it's different than the other ones you guys have been having it seems. My rear defroster will work but only the bottom three rows will defrost. Is there a way to replace the rear defroster or fix it? My friend said that I could probably go to a windshiled repair shop and have them take of it.

Icemark

Then the other rows have been damaged and will need to be repaired.

You can get defroster grid repair paint at most auto parts stores.

You will need to determine where the scratched through lines are, and paint with the defroster grid paint across the scratch.

KingCobraV9

iTrader: (2)

no i hooked it up to a un used connector with 2 wires running into it and one was a 12v keyed wire. that was some how wired into the ps fuse i just wasnna know what it is so i can know if its gonna keep hapning

BadAssRX-7

ok im a fb guy so forgive the stupid question but here is the relay and fuses ill need to be checking on my 89 vert? my defroster stays on 1/2 light with the switch on or off and i get no defrost action on the rear glass.

Icemark

found in the FAQ for FC sticky thread (that is found at the top of this technical section as well as the top of the newbie technical section):

Mr.FC3s

I am gonna hijack for a bit but I have always wanted to take that defroster grid paint clean it all of the window and make a design.

camarols6

where is the power steering computer

Icemark

Right behind the drivers dash speaker

camarols6

^thank you

BadAssRX-7

ok got mine fixed, 2 things wrong with it. #1 the switch was a little cocked in the bezal and wasnt locking from 1 to the other postion(on/off) and 2 there was no fuse in the power ant. spot. slaped in a 10 amp and the 1/2 on lightwent out and the defrost works like it should . Thanks guys.

philiptompkins

iTrader: (4)

Does anyone know where the defrost relay is physically located on an s4 vert?

v-townboy

iTrader: (2)

i am having alot of the same issues, hopefully this thread will help me fix my rear defroster, thanks