rear defroster

**04goatinmass** · 12-09-2005, 08:52 AM

i just noticed that when i hit the button on my rear def it only stays on fo rlike 10secs and goes out and for some reason i try to turn it back on and it seems like its gotta wait period before i can try it again.this happens over and over anyone know why?or how do i test it?

**Pulse Red GTO** · 12-09-2005, 06:05 PM

What I did on mine was put a actual fuse in the fuse box instead of the relay they have in there. I took mine to the dealer & they said that is what it does, only stays on so long. I think I put a 20 or 30 amp in there & it worked awesome from then on out!

redls1bird · 12-09-2005, 07:17 PM

if you have power adjustable seats, they are on the same circuir and also wont work..

**04goatinmass** · 12-10-2005, 06:34 PM

ok what relay is it on under plus what do u mean put a fuse in there wouldnt that burn out the fuse overtime cause the main purpose of the relay is too shut it off after so long cause it becomes too hot

**04goatinmass** · 12-13-2005, 10:30 AM

im still confussed on what to do about this?

**Matto4785** · 12-13-2005, 02:17 PM

Replace the 30amp circuit breaker that controls the defroster and power seats with another, or just use a 30 amp fuse. Though, if you decide to swap with a fuse, you risk blowing it if you ever use the defroster and power seats at the same time.

I just did this a few days ago, defroster was doin the same thing. Just went to the auto store and picked up a new circuit breaker for like 4 bucks.

**04goatinmass** · 12-13-2005, 02:25 PM

any idea on the part number of that circuit breaker and also where is it located?

frederal · 12-26-2005, 05:59 AM

GM has a TSB for this problem that call for installing new fuse box terminals the ID# is:1574990 or PIC3270 the kit part# is 22638255. Note when rear defroster is first turned on it should cycle for 10 minutes and then shut off, this is normal.

**04goatinmass** · 12-28-2005, 05:12 AM

ya the problem with mine is it cycles for like 30 seconds then shuts off but when i try to turn it back on i have to wait like 5 mins or so until i can.where is this fuse box located.is it under the drivers side ?

frederal · 12-28-2005, 06:25 AM

Yes thats what they do when there is that problem. The cause is that the circuit breaker for rear defroster, that is in the fuse box to the left side of the dash (only visible with door opened) will overheat and cause an open circuit. What sets the circuit breaker apart from a fuse is that a fuse will blow permanently. The breaker will work again after it cools down. The cause of the breaker overheating is caused by excessive resistance to the contacts in that fuse box. GM's fix is to install modified contacts in the fuse box for the defroster circuit breaker per their bulletin. Please note that replacing the circuit breaker with a fuse maybe dangerous, could cause wiring to melt or even ignite!!!

frederal · 12-28-2005, 09:46 AM

please note: the 30 amp breaker in the fuse panel on left side of dash is not a relay!!!
the timer is incorporated into the defroster switch in the heater control.

frederal · 12-28-2005, 09:51 AM

Ok everyone listen closey. GM has a Technical Service Bulletin, document ID# 1574990 or PIC3270 dated 12/2/2004, " rear defogger performance, off too soon". Frequent use of the rear defroster when used to clear snow, frost, etc. may cause the circuit breaker and terminals to overheat. Because of this , there is added resistance and ther circuit breaker begins to open at times and this will happen more and more frequently. The lenght of on time gets shorter and shorter. Replace the circuit breaker and the fuse box terminals from kit part# 22638255, this covers 1999 to 2001 models. This has nothing to do with a timer!!!!

**04goatinmass** · 01-03-2006, 05:18 AM

ok i replaced that cb with a 30 amp fuse.seems all the parts stores dont carry that cb for my car and they are like its a dealer part.seems like bs to me so instead i figured i try the 30 amp fuse i need this baby working for there is a major snow storm head my way.so now it works fine but one question my timer is set for 5 mins.i tried numerous times from off and on to see if that would change but its been constantly 5 mins no sooner or later.i heard someone say theres runs for 10 mins.what up with mine that it only runs for 5 mins.dont get me wrong its a huge inprovment from 30 seconds but it took 2 or 3 tries to clear the ice on my window

frederal · 01-03-2006, 07:12 AM

Are you sure it is 5 mins? have you timed it. You should not have a fuse in this, go to the dealer and purchase the correct 30 amp circuit breaker. The reason it turns off faster is caused by excessive resistance at terminals in fuse box. If you wish to solve this refer to the bulletin I mentioned, go to your local Chevy dealer to get a copy of it and order the terminal kit for fuse box. If you have not R&R a fuse box before that leave it to them

**04goatinmass** · 01-03-2006, 09:40 AM

yes im sure i timed it several times.5 min each one exact.as for going to the dealer to have it done your crazy they charge out the ass for a simple thing like this.i know cause i called and asked them.they want $35 bucks for the part and 2 hours labor at $85 an hour so your looking at $205 plus tax for a 2 dollar fix witha fuse.i also tested the curcuit with an amp meter and got no higher then 25amps.i dont have power seats so im not worried about that problem.so why have a cb when the fuse does the same exact job?

**mdcrabbie** · 03-16-2010, 04:35 PM

I checked for the part # 22638255 for the contact kit and can't find any info on this. Is this the right part number? Also anyone have a copy of this Technical Service Bulletin, document ID# 1574990 or PIC3270 dated 12/2/2004, " rear defogger performance, off too soon".

**Smittro** · 03-16-2010, 09:02 PM

Originally Posted by mdcrabbie

I checked for the part # 22638255 for the contact kit and can't find any info on this. Is this the right part number? Also anyone have a copy of this Technical Service Bulletin, document ID# 1574990 or PIC3270 dated 12/2/2004, " rear defogger performance, off too soon".

Take the effected breaker into the parts store any compitent parts person can run it's numbers and give you the breaker you'll need. I have actually had this fixed under warranty (about 4 years ago) and they replaced the switch and the breaker. They did'nt add anything to the fuse panel @ all.. It has worked properly ever since.. The service bulliten is meaningless because they will not fix it for free now..

**mdcrabbie** · 11-17-2010, 05:59 AM

The correct part # is 22638225 for the kit.

**BlueStreak** · 11-23-2010, 06:08 PM

Thanks all, for the info. I'm cheap, so I will try a fuse in mine.

There's one thing I don't understand about safety here. I've seen some comments in this thread, about the possibility of a fuse being more dangerous than the breaker. I'm not following that. In fact, I'd bet a fuse would actually be safer overall. With a breaker, an ignorant owner could just keep hitting the button every time the breaker cools off enough, even though other parts might not be cool. But with a fuse, one over-current and pow! it's open circuit forever.