i bought a '94 cav for a winter car and my rear defrost doesn't work, i have done a search on this problem and read that the wiring burns up. my car has power locks that also don't work, i assume they are on the same circuit? i tested the power wire that feeds the button and i only have .01V, the button and window are good, can anybody help me out, i'd like to have this working for the winter. thx.

first, check your fuses



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First find out for sure if they share the same fuse, I normally dont see power door locks and rear defrogger share the same fuse though.

Than check the fuses and see if they are blown.

Blown means a short to ground before any load takes place.

But if the fuse is good, you have either a bad component someplace or an open.

So let me know when you get more info.

I do a ton of eletrical diagnosis all the time.


- 2004 Cavalier - 124k, owned since new

i have checked all the fuses and they are all good, i don't know if the power locks and the defrost share a circuit or not, i'm just assuming. i looked at the fuse panel and i don't see a fuse that is named for either the defrost or the locks so i don't know which one it is. i assume that the wire that feeds the button for the defrost is broken but not sure, and one more thing where is the blower motor for my heater located? my fan squeeks when the heater is on until the car warms up.

I work at an auto literature shop, and I'm momentarily bored -- so after grabbing an owner's manual for your car, I discovered that door locks and rear defogger on a shared breaker. It's a 30 AMP labeled "ACC" near the bottom right corner. It might still not be the problem, but at least you'll know where to start looking. Here's a snapshop:





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Geeky wrote:I work at an auto literature shop, and I'm momentarily bored -- so after grabbing an owner's manual for your car, I discovered that door locks and rear defogger on a shared breaker. It's a 30 AMP labeled "ACC" near the bottom right corner. It might still not be the problem, but at least you'll know where to start looking. Here's a snapshop:

thx alot for the pic, i'll check it tomorrow and see what size fuse is in it

i pulled the fuse today and it was so hot i couldn't hold it, i bought a new one and put it in, now the defogger works but the locks don't really move, i don't care about them though, the defroster was only on for like 4 min, is there any way i can make it stay on longer?

If it only stayed one for four minutes something is wrong with the timer control for it.




- 2004 Cavalier - 124k, owned since new

That, or the breaker popped again. Sounds like maybe something has gone bad in the wiring.



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drove the car today, defrost works ok, now the locks don't, but that doesn't matter, i have been checking the fuse and its not hot like the other, i don't know what the prob was or how long it will work, where is my blower motor located for my heater? i have a parts car and mine needs to be replaced.

an update, after about a week of driveing the defroster will stop working and the fuse will get very hot, i pulled the fuse box and looked at the wires in this circuit and one of the wires looks pretty burnt, i would like to snip one of the wires coming off the fuse block and just put a new one in that goes directly to the defroster button but i don't know which one to cut, or if it makes a difference. thx. ryan.

Sounds like you have an intermittent short to ground after the fuse. intermittent shorts are usually caused by a cracked or stripped wire somewhere along the line, which occasionally makes contact. What is happening is that the circuit is being completed before the defrost timer unit, running constant power through that fuse, (and power with no load means it's pulling a LOT through that fuse). I would check the wiring personally and focus on bends or places that run along metal framework- especially bolts. hope that helps.

http://www.j-body.org/forums/read.php?f=11&i=116103&t=116103

Is this any help


Alont

jd, i don't think it is a broken wire for my defroster, it works fine, i think my locks have a broken wire or a short somewhere, they have never worked since i bought the car, and i think if i by pass the locks and just run the power wire to the switch for the defroster it will work fine, alont, thx for the link but i don't have a clue what wires are being talked about.

Ryan

if it's any help my '93 has an orange/black wire running from the 30 amp breaker to a splice,

one wire of the splice goes to the door locks

and the other to the defogger control assy(switch)



1. If you can locate the splice, it's part of the Instrument Panel harness, near the parking brake lever, cut the wire that goes to the door locks and insulate both ends.


2. The wire talked about in the link IS the wire from the 30 amp breaker to the rear defogger element. It runs through a connector, mine is C200 behind the instrument panel near the LH shroud. This connector seems to have a [roughly speaking-- thick wire running through a thin contact] and the contact overheats and give a high resistance.What the posters have done is bypass this bad connection with a wire link and everything works as advertised.

Just in case any of this helps


Alont

Alont, you have a pm

Hi Ryan

If you start at the 30amp breaker in the fuse panel, an Orange/Black wire runs to a splice(on mine it's roughly underneath the ashtray,you have to take the prnd/gear lever and center console off to get to it)

30amp bkr----splice (S257)-----------Door locks

sameSplice(S257)--------F3Pin-C200connector--

--c327connector----------^^^^defogger grid^^^^^^^^----

----C304 connector-------------Ground point G314

(Under carpet behind drivers seat)

The splice joins two wires on to the one you started with, 1 goes to the door locks and the other to connector C200(somewhere on the panel to th LHS of the the drivers feet, in front of the door hinges, behind the carpet)and then on to the defogger.If you can find this C200 connector and Pin/Socket F3 is overheated or corroded this is what the guys were bypassing using 12 AWG wire and two quick connectors.

The type of connector is shown in this link:-

http://www.j-body.org/forums/read.php?f=11&i=97396&t=97396

I have had net connection probs here due to weather-prob why things have been corrupted

Alont

ok, i pulled the seat & carpet out, no wires there except for the seat belt light/wire. i tried to cut one of the wires coming out of the fuse block and hook it up to the red on my heater controls for the defroster, well the defroster was always on, the switch wouldn't do anything, i've tried following the wire up to see where it splits off coming out of the fuse panel but i can't find it....where else do you think this burnt connector would be?