Having problems with "high voltage"...anyone know what would cause this?
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,533
Likes: 1
From: North Aurora IL
Having problems with "high voltage"...anyone know what would cause this?
My car sat for a month and I took it out last night and today. When I was driving the volts would go from 14, down to 11, then spike to 16! After a few minutes it would go back to normal. Then it would start going nuts. Consistantly going from low to extremely high. DIC comes on "High Voltage".
I took it to advance to have the battery and alternator checked out. They said it was good, but my starter appears to be loosing voltage. I dont have any problems with the starter though. Plus Im getting to much voltage. Would a loose connection cause this?
After leaving it was normal and stayed that way for about an hour. Now it is staying 15.4-16! Is something in the alternator going bad? The battery is an optima (1 year old) stock alternator (02 w/45K miles).
I checked the chassis grounds on both driver/pass side. They look new. Cleaned battery terminals (they looked new).
02 Z06
408ci
Procharger D1SC with A&A Bracket stock pulley
Snow Performance meth kit -boost ref-(recently added and powered to fuse box and has its own ground)
KB BAP
Racetronix Fuel system
Anyone have similar problems? or Ideas?
Thanks
I took it to advance to have the battery and alternator checked out. They said it was good, but my starter appears to be loosing voltage. I dont have any problems with the starter though. Plus Im getting to much voltage. Would a loose connection cause this?
After leaving it was normal and stayed that way for about an hour. Now it is staying 15.4-16! Is something in the alternator going bad? The battery is an optima (1 year old) stock alternator (02 w/45K miles).
I checked the chassis grounds on both driver/pass side. They look new. Cleaned battery terminals (they looked new).
02 Z06
408ci
Procharger D1SC with A&A Bracket stock pulley
Snow Performance meth kit -boost ref-(recently added and powered to fuse box and has its own ground)
KB BAP
Racetronix Fuel system
Anyone have similar problems? or Ideas?
Thanks
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
My 1st guess would be battery-they tend to make alternators OVERCHARGE when they are on their last legs. Put the car on a trickle charger and see if it will fully charge SLOWLY. If it does, start the car and see what the voltage is.
3rd Gear
Joined: Sep 2007
Posts: 3
Likes: 0
I'm having the same problem.
2000 C5
14.9v at cruising speed is boiling the battery. Sometimes when RPM drops to idle, it'll go down to 12.9 for an instant, then back up. All lights are pulsating while driving.
125k miles. 6 month old battery.
This happened shortly after I deep cycled the battery while installing a satellite radio receiver. I should have used a battery charger, but it fired up so I just drove it that way and let the alternator charge it up from near dead.
Sounds like a bad regulator, right? I checked and cleaned the battery terminals. They were pretty bad, but it didn't help. I cleaned the chassis grounds that I could find from above. Didn't help.
So is it time for a new alternator? I hate throwing parts at a problem. Is there a diagnosis procedure? Am I asking for trouble if I use an Autozone remanufactured unit?
2000 C5
14.9v at cruising speed is boiling the battery. Sometimes when RPM drops to idle, it'll go down to 12.9 for an instant, then back up. All lights are pulsating while driving.
125k miles. 6 month old battery.
This happened shortly after I deep cycled the battery while installing a satellite radio receiver. I should have used a battery charger, but it fired up so I just drove it that way and let the alternator charge it up from near dead.
Sounds like a bad regulator, right? I checked and cleaned the battery terminals. They were pretty bad, but it didn't help. I cleaned the chassis grounds that I could find from above. Didn't help.
So is it time for a new alternator? I hate throwing parts at a problem. Is there a diagnosis procedure? Am I asking for trouble if I use an Autozone remanufactured unit?
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,533
Likes: 1
From: North Aurora IL
Wow...that is exactly the same thing. My battery was low and it fired up so I let it idle and then drove it to charge it back up.
THE PROBLEM
Bad voltage regulator in the alternator. The alternator itself is fine.
CHEAPER FIX
Find a shop that rebuilds alternators. One by me in DeKalb IL is going to replace it for $60-90. Drop off and wait while he does it.
try googling alternator repair shop in your city.
Good luck.
THE PROBLEM
Bad voltage regulator in the alternator. The alternator itself is fine.
CHEAPER FIX
Find a shop that rebuilds alternators. One by me in DeKalb IL is going to replace it for $60-90. Drop off and wait while he does it.
try googling alternator repair shop in your city.
Good luck.
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
If you are getting wild voltage fluctuations, I would check the grounds.
Check the battery to see if it has over 12 volts when not charging.
In the old days, voltage regulators could stick wide open and cook the battery, or they could fail, and not charge at all. Now, I think the PCM also monitors the alternator output and if the alternator is not needed, the PCM can turn the alternator off. It may also check for abnormally high voltage.
Do you have any codes? P1637?
Check the battery to see if it has over 12 volts when not charging.
In the old days, voltage regulators could stick wide open and cook the battery, or they could fail, and not charge at all. Now, I think the PCM also monitors the alternator output and if the alternator is not needed, the PCM can turn the alternator off. It may also check for abnormally high voltage.
Do you have any codes? P1637?
Tech Contributor
Joined: May 2008
Posts: 3,100
Likes: 17
From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
3rd Gear
Joined: Sep 2007
Posts: 3
Likes: 0
With an immediate need to have the car in usable condition, I went ahead and dropped in an Autozone reman alternator. "Refurbished in Mexico". Guess we outsource everything nowadays.
13.8v steady.
Must have fried the regulator on the old one.
13.8v steady.
Must have fried the regulator on the old one.
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Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
These kind of reports are normally only associated with bad batteries, bad alternators or bad electrical connnections at either the battery or the start solenoid where these all come together.
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,533
Likes: 1
From: North Aurora IL
Thanks for all your help guys. I checked everything I could without throwing money at it. Turns out its my voltage regulator.
Had the optima retested to be sure its ok. I didnt have the problem very long at all. Plus when it spiked to high voltage I pulled over and shut it off.
I never had any codes. Thanks again.
Had the optima retested to be sure its ok. I didnt have the problem very long at all. Plus when it spiked to high voltage I pulled over and shut it off.
I never had any codes. Thanks again.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Glad you found it. My 2000 did exactly the same thing, jumping to 16V, then down to 11, then normal. Turned out to be the connection at the starter solenoid. Guess I was lucky, the alt/reg checked out fine, and it's been good for over a year now after the bolt tightening.
DG
DG
2nd Gear
Joined: Oct 2009
Posts: 2
Likes: 0
hey guys Orlando Green here i have a 99 corvette drives fine until i cut it off. When i cut it off the car will not restart, pulled up the codes on the body control module it said not communicating. Disconnect BCM center plug car ran fine. Turned the car off 15min later same problem. My question is can i buy my BCM and just plug it in or do i have to take it and get it reset,also i pluged bcm back in after diconnecting ran fine .
Last edited by orlando green; Oct 21, 2009 at 04:57 PM.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
hey guys Orlando Green here i have a 99 corvette drives fine until i cut it off. When i cut it off the car will not restart, pulled up the codes on the body control module it said not communicating. Disconnect BCM center plug car ran fine. Turned the car off 15min later same problem. My question is can i buy my BCM and just plug it in or do i have to take it and get it reset,also i pluged bcm back in after diconnecting ran fine .
