Rear Defroster Time
#1
Rear Defroster Time
When I turn the rear defroster on on my '87 TA it works, but it cuts off _way_ too fast, like something on the order of after a minute or 2. The whole grid works, it seems to turn on and off correctly, just the relay cuts out really fast. I also tried pulling the relay from my '87 parts car and swapping it and it does the same thing.
Any idea what might be causing it? alternatively, is there any way to make the thing stay on much longer (if I remember right it's supposed to stay on for 11 min, something like 11-15 min would be nice)
Any idea what might be causing it? alternatively, is there any way to make the thing stay on much longer (if I remember right it's supposed to stay on for 11 min, something like 11-15 min would be nice)
#3
On Probation
Re: Rear Defroster Time
My 84 does the same as yours!
Since you swapped the relay I know thats not the cure to the problem.
I guess I will chalk it up to the cars old age...................
Since you swapped the relay I know thats not the cure to the problem.
I guess I will chalk it up to the cars old age...................
#4
Supreme Member
iTrader: (4)
Re: Rear Defroster Time
I dont think the relay has anything to do with the timing of the heat. Its either a separate unit...like in the convenience center, or in the switch itself. PRETTY sure its controlled within the switch but dont quote me. I know mine on my 86 and on my 87 stayed on longer than a couple minutes. Not sure if it was quite 11, but a good deal more than 2.
Check the wiring diagram, or google/search around here. Gotta be some info on it.
J.
Check the wiring diagram, or google/search around here. Gotta be some info on it.
J.
#5
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
I would think it's the Timer Relay,what else could it be,maybe the Defogger Switch itself ??
The Defogger Relay is located on the R/H side of the I/P near the ECM. P/N 10017711.
Hope this helps you out.
It's supposed to run for 10 mins.if you hit it off and on 2 times it will run for 5 mins.
The Defogger Relay is located on the R/H side of the I/P near the ECM. P/N 10017711.
Hope this helps you out.
It's supposed to run for 10 mins.if you hit it off and on 2 times it will run for 5 mins.
Last edited by mantaguy; 12-06-2012 at 01:09 PM.
#6
Re: Rear Defroster Time
Right, this thing:
I have 2 of them sitting around, I tried both, they both turn off at between 35 and 37 seconds. Unless they tend to fail the same way (not sure what that failure would be, it looks like it's just a simple solid state timer circuit and a relay inside), I'm not sure that replacing it with a 3rd one will make any difference. I don't know what else to check... I'm wondering if i might have intermittent power or ground to it causing it to shut off momentarily like when I hit a bump, but I don't have a really good idea how to check that.
I have 2 of them sitting around, I tried both, they both turn off at between 35 and 37 seconds. Unless they tend to fail the same way (not sure what that failure would be, it looks like it's just a simple solid state timer circuit and a relay inside), I'm not sure that replacing it with a 3rd one will make any difference. I don't know what else to check... I'm wondering if i might have intermittent power or ground to it causing it to shut off momentarily like when I hit a bump, but I don't have a really good idea how to check that.
#7
On Probation
Re: Rear Defroster Time
Just a thought...................
The weather has turned real cold and snowy here in NY.
My car was parked outside and snow covered. I started it up and let it run with
the rear defrost on. The rear defog stayed on for a good 10 minutes and melted
the snow off the back window!
I wonder if the outdoor temp. or window temp has something to do with the
extended defrost time????
The weather has turned real cold and snowy here in NY.
My car was parked outside and snow covered. I started it up and let it run with
the rear defrost on. The rear defog stayed on for a good 10 minutes and melted
the snow off the back window!
I wonder if the outdoor temp. or window temp has something to do with the
extended defrost time????
Trending Topics
#8
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
I would seriously check the 35 amp circuit breaker and defogger switch,unless you have 2 bad relays that your using,
#11
Supreme Member
iTrader: (4)
Re: Rear Defroster Time
I just wanted to make sure. I replaced some really corroded wires in the back and it still stays on for only about 1-2 min initially, alot less if I push it again. Kind of a bummer really. I was hoping that the corroded wires were creating a resistance that was popping the relay. Guess not. hehe Now I have to order one, wait 7-10 business days for it to ship to the UK and pay a rediculous amount for international shipping. /sigh haha Ah the life of not living in the US with an American car. hehehe
#12
Re: Rear Defroster Time
your picture is fuzzy so I can't tell if it says 35 or 30A, but interestingly, both my '87's had 2 30A breakers in them. I swapped both (didn't bother checking which one was actually the defroster breaker, quicker to just swap both) from my formula (where the defroster was working correctly) into my TA... I'll try it tonight when I go to the gym. I suppose that the breaker might just be intermittent...
#13
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
Sorry about the fuzzies,it would be a 35 amp circuit breaker.
They do reset.
They do reset.
#14
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
Window defogger, Relay
Window defogger, Switch
Pontiac, w/o Spl Ed Trans Am
List Price : $31.09 switch
Your Price : $24.87
All Models
List Price : $51.93 relay
Your Price : $41.54
WOW!!!these are expensive.
Window defogger, Switch
Pontiac, w/o Spl Ed Trans Am
List Price : $31.09 switch
Your Price : $24.87
All Models
List Price : $51.93 relay
Your Price : $41.54
WOW!!!these are expensive.
#16
Supreme Member
iTrader: (8)
Join Date: Aug 2003
Location: LeRoy, NY
Posts: 7,240
Likes: 0
Received 6 Likes
on
5 Posts
Car: 2003 Hyundai Tiburon GT
Engine: 2.7L V6
Transmission: 6-speed
Axle/Gears: 4.41
Re: Rear Defroster Time
Try swapping out the switch. Yes, it may work, but there may be an issue with the OFF button that's turning the defogger off early.
The timer is supposed to be on for 10 minutes the first time the ON switch is pressed and 5 every time after that until the ignition is turned off.
The timer is supposed to be on for 10 minutes the first time the ON switch is pressed and 5 every time after that until the ignition is turned off.
#17
Supreme Member
iTrader: (4)
Re: Rear Defroster Time
I've ordered the relay. I can hear it clicking, more than once when i turn it on. One time it actually buzzed at me like it was continuously flipping states on/off. We'll see if that fixes it. I'll keep you guys posted. Should be getting the relay in the mail in the next week or so.
#18
Re: Rear Defroster Time
Try swapping out the switch. Yes, it may work, but there may be an issue with the OFF button that's turning the defogger off early.
The timer is supposed to be on for 10 minutes the first time the ON switch is pressed and 5 every time after that until the ignition is turned off.
The timer is supposed to be on for 10 minutes the first time the ON switch is pressed and 5 every time after that until the ignition is turned off.
#19
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
Not supposed to stay on for 3 minutes,nor 30-40s minutes,it's got to be the timer relay because it's not consistent with the way the relay works.
#21
Member
iTrader: (1)
Join Date: Apr 2010
Location: Montana
Posts: 405
Likes: 0
Received 4 Likes
on
4 Posts
Car: '84 Firebird TA & '87 Camaro LT
Engine: 350 V-8 & V-6
Transmission: 700R4
Axle/Gears: 3.23 & 3.42
Re: Rear Defroster Time
I've ordered the relay. I can hear it clicking, more than once when i turn it on. One time it actually buzzed at me like it was continuously flipping states on/off. We'll see if that fixes it. I'll keep you guys posted. Should be getting the relay in the mail in the next week or so.
Where did you get the relay? My parts guy said they were no longer available.
#22
Supreme Member
iTrader: (4)
Re: Rear Defroster Time
GM parts direct I Think it was. I just put the part number in google and found it that way.
----
Edit
----
I just learned they refunded my payment through paypal....crap.
Well, time to start looking again.
----
edit
----
I've found one used one on Ebay.
----
Edit
----
I just learned they refunded my payment through paypal....crap.
Well, time to start looking again.
----
edit
----
I've found one used one on Ebay.
Last edited by Ozz1967; 01-04-2013 at 11:55 PM.
#23
Supreme Member
iTrader: (5)
Join Date: Nov 2010
Location: Mantua NJ
Posts: 5,845
Received 74 Likes
on
66 Posts
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: Rear Defroster Time
You could try your local GM dealer for the part and if they don't have one, they will supply you with a list of other dealers that may have them in stock.
#25
Junior Member
Join Date: Apr 2013
Location: Craig, Colorado
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
Engine: 5.7L TPI
Transmission: T-5
Re: Rear Defroster Time
Has anyone tried measuring the voltage across the circuit? I always thought that as the grid heated up it passed either more or less voltage, causing the relay to open when it reached a particular potential. For example 12 volts applied to the circuit would let a small amount of amps through if the resistance was high. As the grid heated up the material would become more conductive and thus the resistance would drop. This would increase the amount of voltage that was allowed back to the relay. Probably not right but might be worth investigating.
#27
Junior Member
Join Date: Apr 2013
Location: Craig, Colorado
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
Engine: 5.7L TPI
Transmission: T-5
Re: Rear Defroster Time
Well resistance on some things increase with heat. On other devices resistance decreases (like in a coolant sensor for example, 450 ohms at 70 deg. 0 ohms at 285 deg). I haven't had a chance to check how the defroster circuit reacts to heat yet, but the idea was that perhaps the relay was sensitive to voltage or current changes. Just an if the timed relay idea wasn't resolving.
#28
Member
Join Date: Oct 2011
Location: British columbia, Canada
Posts: 398
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1986 Firebird
Engine: 5.0L V8
Transmission: T-5
Axle/Gears: 2.73
Re: Rear Defroster Time
thats why if you watch breakout kings or whatever it is and they defuse the bomb with the freyon, you can say thats incorrect. lol
Thread
Thread Starter
Forum
Replies
Last Post
AkDrifted
Engine/Drivetrain/Suspension Parts for Sale
6
08-17-2015 07:45 PM