Electrical Issues
Thread Starter
Instructor
Joined: Dec 2001
Posts: 210
Likes: 0
From: Helotes TX
Electrical Issues
I am having 3 electrical issues that I need help with:
1- When I turn on my rear defroster, the defroster indicator light comes on for 2-3 seconds then goes out. I have checked all the wires and fuses and they are fine with good connections. I even tried unhooking the rear window wires but there was no difference.
2-The range for my PKE on the left door is about 1 foot and next to nothing on the right. I have changed the battery in the fob but no change. Can the range be increased?
3-Periodically when driving all my lights will dim for a second then brighten up again. I am thinking alternator but it always shows it charging at 13-14 volts. I have a new Optima Red Top installed so I am a little perplexed.
Any help or tips are greatly appreciated!
1- When I turn on my rear defroster, the defroster indicator light comes on for 2-3 seconds then goes out. I have checked all the wires and fuses and they are fine with good connections. I even tried unhooking the rear window wires but there was no difference.
2-The range for my PKE on the left door is about 1 foot and next to nothing on the right. I have changed the battery in the fob but no change. Can the range be increased?
3-Periodically when driving all my lights will dim for a second then brighten up again. I am thinking alternator but it always shows it charging at 13-14 volts. I have a new Optima Red Top installed so I am a little perplexed.
Any help or tips are greatly appreciated!
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
#1. I'm not at home and dont have the Vette or my manuals with me but if my memory serves me well, on my 90 the rear window and mirror defrosters are fused by a circuit breaker (one of those larger square silver things in the fuse box). The thing about circuit breakers is they open when there's an overload or short then close when they cool. This could be why the light lights up then shuts off but then lights up again the next time you push the button. The problem could be a faulty circuit breaker. Then again there could be a short causing it.
#2. I dont have a clue as my 90 has no PKE's but I'd be willing to bet there's an antenna wire for the PKE reciever and it's either been pulled loose or fallen off or something.
#3. Sounds like loose ground(s). Check battery connections first then check for your central ground location. On the L98 its on block just above oil filter. On your Lt1 I'm not sure but find it and clean and tighten all the ground connectors there.
Hope this helps but if not at least it's a bump TTT.
#2. I dont have a clue as my 90 has no PKE's but I'd be willing to bet there's an antenna wire for the PKE reciever and it's either been pulled loose or fallen off or something.
#3. Sounds like loose ground(s). Check battery connections first then check for your central ground location. On the L98 its on block just above oil filter. On your Lt1 I'm not sure but find it and clean and tighten all the ground connectors there.
Hope this helps but if not at least it's a bump TTT.
Racer
Joined: Sep 2004
Posts: 323
Likes: 1
From: Muncie Indiana
Alternator
I had the same problem with the light dimming and go bright on another GM car. Had three different places check the system and all said it was ok.
Went to radio shack and bought a plug for the lighter with a fuse and an on off switch with bare wires.. Took a voltmeter and hooked it up to the bare wires. When I was driving and saw the light flicker I turned on the volt meter to see if the voltage was dropping or spiking to high. What I found was that the voltage dropped. I then found out that the alternator has a breaker in it and it was breaking open and the car was running on the battery until the breaker reset itself. Bottom line was I finally found a service bulletin describing the cure as a new Alternator. New alt in and all is well. One last thing to check first would be to make sure the battery terminals are tight. Not only the wires and bolts but the actual terminal into the battery. Have had them go bad and actually fall out of the battery dumping acid all over the inside of the engine bay.
Went to radio shack and bought a plug for the lighter with a fuse and an on off switch with bare wires.. Took a voltmeter and hooked it up to the bare wires. When I was driving and saw the light flicker I turned on the volt meter to see if the voltage was dropping or spiking to high. What I found was that the voltage dropped. I then found out that the alternator has a breaker in it and it was breaking open and the car was running on the battery until the breaker reset itself. Bottom line was I finally found a service bulletin describing the cure as a new Alternator. New alt in and all is well. One last thing to check first would be to make sure the battery terminals are tight. Not only the wires and bolts but the actual terminal into the battery. Have had them go bad and actually fall out of the battery dumping acid all over the inside of the engine bay.
Thread Starter
Instructor
Joined: Dec 2001
Posts: 210
Likes: 0
From: Helotes TX
Thanks for the tips. Here is what I have found:
- The inside fuse box does not contain a breaker for the rear defrost, only for the windows & seats. Any other thoughts on where to look?
- I think the breaker in the altenator is the problem with the flickering. It has done it for the last 19K miles so it is probably time to pull alternator off and rebuild it.
- Have not had a chance to pull the door panels but I believe there are antennas on each door and will have to check those.
I appreciate the help!
- The inside fuse box does not contain a breaker for the rear defrost, only for the windows & seats. Any other thoughts on where to look?
- I think the breaker in the altenator is the problem with the flickering. It has done it for the last 19K miles so it is probably time to pull alternator off and rebuild it.
- Have not had a chance to pull the door panels but I believe there are antennas on each door and will have to check those.
I appreciate the help!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
On my 87, the defogger circuit breaker is a 35 amp unit in the fuse block. Listen for the circuit breaker to click, that will be a clue if it is the breaker. Also, there is a timer for the defogger in the a/c control assembly and it may be timing out in a much shorter time than 10 minutes as it is supposed to do.
Thread Starter
Instructor
Joined: Dec 2001
Posts: 210
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From: Helotes TX
Originally Posted by jfb
On my 87, the defogger circuit breaker is a 35 amp unit in the fuse block. Listen for the circuit breaker to click, that will be a clue if it is the breaker. Also, there is a timer for the defogger in the a/c control assembly and it may be timing out in a much shorter time than 10 minutes as it is supposed to do.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The timer operates a relay that switches 12v to the defogger, so a pinched wire shouldn't affect the timer and the circuit breaker should protect the relay from a pinched shorted wire. You still need to check out the breaker. The defogger draws 24 amps, so you could measure the battery current when you turn on the defogger and see if it is in the correct range. A pinched wire will draw a bunch more than 24 amps.
Thread Starter
Instructor
Joined: Dec 2001
Posts: 210
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From: Helotes TX
Originally Posted by jfb
The timer operates a relay that switches 12v to the defogger, so a pinched wire shouldn't affect the timer and the circuit breaker should protect the relay from a pinched shorted wire. You still need to check out the breaker. The defogger draws 24 amps, so you could measure the battery current when you turn on the defogger and see if it is in the correct range. A pinched wire will draw a bunch more than 24 amps.
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Thread Starter
Instructor
Joined: Dec 2001
Posts: 210
Likes: 0
From: Helotes TX
I figured out the defroster problem: There is no circuit breaker, just a huge 40amp fuse located in the ECM Fuse Block behind the battery. In my case a blown fuse, obviously from the pinched wire.
Thanks for all the help and tips!
Thanks for all the help and tips!
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Wow! You really did some research to find this 14 year old thread! This is the wrong way to ask a question. Most readers won't wade thru all this old stuff! Please start a new thread for a new question, and tell us a little about your car (year is VERY important) and what you've done to track down your problem.
And, welcome to the Forum!
And, welcome to the Forum!
Melting Slicks
Joined: May 2007
Posts: 2,075
Likes: 109
From: Longmont Co
Wow! You really did some research to find this 14 year old thread! This is the wrong way to ask a question. Most readers won't wade thru all this old stuff! Please start a new thread for a new question, and tell us a little about your car (year is VERY important) and what you've done to track down your problem.
And, welcome to the Forum!
And, welcome to the Forum!
In addition, the OP eventually says that there is no such circuit breaker.
