High Voltage error need to use car
Thread Starter
Instructor
Joined: Sep 2010
Posts: 184
Likes: 0
From: Logan Township Nj
High Voltage error need to use car
Hi all. Once in a while I get a high voltage warning and my gauges go out... I can see my speed and rpm with my HUD. I read it could be the regulator in my alternator (saw in another post). For the first time the other day I saw a low voltage warning and I saw the needle dropping down. I was idle in my garage... I only have one car right now and that is mine (hubby's car is in the shop)... what harm will I do driving my car if the gauges go out and it says high voltage?
My car does sit and I get it out once a week or so... no problems starting up... battery is less thsn 1 yr old (optima yellow top).
My car does sit and I get it out once a week or so... no problems starting up... battery is less thsn 1 yr old (optima yellow top).
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Most likely the alternator regulator is bad. Be careful it does not boil/overcharge the battery and put acid on the PCM computer module below the battery. Please check around the battery for any signs of leakage you may need to clean up.
Could be a bad battery also. I would get them both tested.
Could be a bad battery also. I would get them both tested.
Thread Starter
Instructor
Joined: Sep 2010
Posts: 184
Likes: 0
From: Logan Township Nj
Going to go check things out again today again to see if I can figure it out... what is happening now is i get a low voltage error and watch the gauge needle drop all the way down and then up again. Weird I am getting both high and low voltage errors during a single start up now. No noticable dimming of lights. Guess I have to get it to a shop because this wont fix itself (originally thought it was acting crazy because my car doesnt get driven much... 1x every 2 weeks or 3 weeks).
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You MOST LIKELY either have corroded, dirty or a poor connection on the starter solenoid OR loose/dirty or damaged BATT connection on the back of the alternator under the rubber boot.
The charging and alternator feed back voltage wires orginate thru the starter solenoid. The batteyr also connects there and receives its charging voltage and supplies field voltage to the alternator thru those connections
Jack up the car and make sure that the solenoid connections are not damaged/ burnt/ loose/ corroded.
Make sure that the BATT connection on the back of the alternator is tight and not burnt.
Make sure that the plug on the top of the alternator is not damaged. One of the red wires should have battery voltage on it at all times! That wire is the output reference feed back wire and controls the alternator output voltage. If it is compromised, it can and will cause the output voltage to read very high!
I also recommend removing, cleaning and properly tighting the battery terminal connections. 97-2003 C5 = 11 foot pounds of torque for correct trouble free connections.
The charging and alternator feed back voltage wires orginate thru the starter solenoid. The batteyr also connects there and receives its charging voltage and supplies field voltage to the alternator thru those connections
Jack up the car and make sure that the solenoid connections are not damaged/ burnt/ loose/ corroded.
Make sure that the BATT connection on the back of the alternator is tight and not burnt.
Make sure that the plug on the top of the alternator is not damaged. One of the red wires should have battery voltage on it at all times! That wire is the output reference feed back wire and controls the alternator output voltage. If it is compromised, it can and will cause the output voltage to read very high!
I also recommend removing, cleaning and properly tighting the battery terminal connections. 97-2003 C5 = 11 foot pounds of torque for correct trouble free connections.
2nd Gear
Joined: Aug 2019
Posts: 2
Likes: 0
From: Palm Coast, FL
Hi all. Once in a while I get a high voltage warning and my gauges go out... I can see my speed and rpm with my HUD. I read it could be the regulator in my alternator (saw in another post). For the first time the other day I saw a low voltage warning and I saw the needle dropping down. I was idle in my garage... I only have one car right now and that is mine (hubby's car is in the shop)... what harm will I do driving my car if the gauges go out and it says high voltage?
My car does sit and I get it out once a week or so... no problems starting up... battery is less thsn 1 yr old (optima yellow top).
My car does sit and I get it out once a week or so... no problems starting up... battery is less thsn 1 yr old (optima yellow top).
lotzacarz here 01 Z06 17,000 always garaged never in rain getting high voltage warning, low voltage warning gauges all go dead. Absolutely NO corrosion anywhere Alternator perfect (changed anyway) brand new battery (exactly the one the car calls for-always has been). Wires are all tight. Sent instrument cluster out to be diagnosed. Checked perfect. Put cluster back in>> 3 seconds later> high voltage warning! Volt gauge went up. Gauges all died. At wits end!!!!! NO ONE HAS "THE" ANSWER!
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,601
Likes: 4,060
From: Cape Coral, Florida
Could possibly be a bad PCM…if you want to wait 2 weeks (just had minor back surgery today) and drive the car across the state I’d be happy to look at it…I’d throw the lab scope on the L and F terminals at the alternator connector and see what’s it’s showing !!..and WELCOME to the Forum. !!..BTW I can recommend an excellent diagnostic shop in Melbourne if you want to go that route.
Last edited by C5 Diag; Nov 3, 2021 at 05:09 PM.
4th Gear
Joined: Oct 2023
Posts: 3
Likes: 0
lotzacarz here 01 Z06 17,000 always garaged never in rain getting high voltage warning, low voltage warning gauges all go dead. Absolutely NO corrosion anywhere Alternator perfect (changed anyway) brand new battery (exactly the one the car calls for-always has been). Wires are all tight. Sent instrument cluster out to be diagnosed. Checked perfect. Put cluster back in>> 3 seconds later> high voltage warning! Volt gauge went up. Gauges all died. At wits end!!!!! NO ONE HAS "THE" ANSWER!
Did you ever find what the problem was? I am having the same problems
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
If you have a HIGH VOLTAGE message, Put a volt meter on the battery terminals (engine running ) and see what voltage the system is seeing. Is the alternator actually outputting a high voltage??? Should be 13.5 to 14.5 VDC.
The alternator gets a feed back reading from the red sense wire that attaches to the starter main terminal and it goes back to the alternator on the small plastic plug that connects to the side of the alternator. See if that wire has continuity to and from the alternator to the starter.
I agree,, Start a new post for more direct assistance.
Bill
The alternator gets a feed back reading from the red sense wire that attaches to the starter main terminal and it goes back to the alternator on the small plastic plug that connects to the side of the alternator. See if that wire has continuity to and from the alternator to the starter.
I agree,, Start a new post for more direct assistance.
Bill
4th Gear
Joined: Oct 2023
Posts: 3
Likes: 0
If you have a HIGH VOLTAGE message, Put a volt meter on the battery terminals (engine running ) and see what voltage the system is seeing. Is the alternator actually outputting a high voltage??? Should be 13.5 to 14.5 VDC.
The alternator gets a feed back reading from the red sense wire that attaches to the starter main terminal and it goes back to the alternator on the small plastic plug that connects to the side of the alternator. See if that wire has continuity to and from the alternator to the starter.
I agree,, Start a new post for more direct assistance.
Bill
The alternator gets a feed back reading from the red sense wire that attaches to the starter main terminal and it goes back to the alternator on the small plastic plug that connects to the side of the alternator. See if that wire has continuity to and from the alternator to the starter.
I agree,, Start a new post for more direct assistance.
Bill
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
This tread was started in 2013, and then replies were made in 2021, doubtful that the person who had this same problem will reply. You might think of pulling the alternator and having it tested at your nearest auto parts store.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I checked the output voltage from the alternator and it reads 14.2v. i checked the battery ( i actually purchased a new one). I changed the starter thinking that was the problem because of a bad solenoid.. i checked all the grounds and all the fuses and i still get the.. CHARGE SYSTEM FAULT.. HIGH VOLTAGE.. As soon as i start the engine the volts get high and when it reaches over 16v all the gauges go dead
Bill
4th Gear
Joined: Oct 2023
Posts: 3
Likes: 0
You either have a bad regulator, connector to the regulator or that small red wire that connects to the solenoid main terminal is compromised/broken!!! Get an ohm meter and check that wire for proper continuity. Check that White/clear plastic connector on the side of the alternator for damage / melted /corroded pins.
Bill
Bill
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I checked the output voltage from the alternator and it reads 14.2v. i checked the battery ( i actually purchased a new one). I changed the starter thinking that was the problem because of a bad solenoid.. i checked all the grounds and all the fuses and i still get the.. CHARGE SYSTEM FAULT.. HIGH VOLTAGE.. As soon as i start the engine the volts get high and when it reaches over 16v all the gauges go dead
Bill
If you measure that wire with a DC Volt meter to ground, It must/should read full battery voltage at all times. Look at the pins inside the end of the connector. Are they clean and tight? Do they make solid connections inside the alternator?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
If you measure that wire with a DC Volt meter to ground, It must/should read full battery voltage at al times. Look at the pins inside the end of the connector. Are they clean and tight? Do they make solid connections inside the alternator?