C2 charging system problem
Thread Starter
Drifting
Joined: Aug 2014
Posts: 1,633
Likes: 135
C2 charging system problem
Perhaps my search wording is wrong The car is charging but the gauge does not indicate so. The 1.5 volt battery test indicates the gauge is not the fault.(swings to +40) Multimeter says I'm charging Gauge never moves from 0.. I know the horn relay is in that circuit but the horn works. having trouble getting to the source of the issue. Any ideas???
Thread Starter
Drifting
Joined: Aug 2014
Posts: 1,633
Likes: 135
Been a long time since I worked on a C2 As I recall, the meter does not show actual voltage or amps but a "differential". Right now, I know the battery is not fully charged so I think I should be showing + something indicating the system is being told from the regulator to charge the battery.. I'm fairly confident something is wrong.
Melting Slicks
Joined: May 2001
Posts: 2,749
Likes: 776
From: Dadeville AL
Is this a change from previous operation?
Does the gauge move when you turn on the lights (all of them) at idle?
Does the gauge move when you blow the horn (at idle)?
Using a multimeter, what is the battery voltage with everything off?
Does the gauge move when you turn on the lights (all of them) at idle?
Does the gauge move when you blow the horn (at idle)?
Using a multimeter, what is the battery voltage with everything off?
Team Owner
Joined: Feb 2003
Posts: 54,106
Likes: 9,421
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
Been a long time since I worked on a C2 As I recall, the meter does not show actual voltage or amps but a "differential". Right now, I know the battery is not fully charged so I think I should be showing + something indicating the system is being told from the regulator to charge the battery.. I'm fairly confident something is wrong.
Thread Starter
Drifting
Joined: Aug 2014
Posts: 1,633
Likes: 135
This car is new to me. I'm getting it ready for safety inspection for a friend. I am a retired mechanic with a fair amount of C2 and C3 experience. FYI the gauge never moves running or not.
Safety Car
Joined: Mar 2009
Posts: 4,191
Likes: 951
From: Corpus Christi, TX
Did you do the 1.5 volt battery test just to the gauge or from end to end? End to end, which is from the black/white wire at the horn relay to the black/white wire at the starter solenoid, will check the entire meter circuit. Be sure to disconnect the battery for that test.
.
Normal gauge behavior is slight or a bit more to the + side after cranking and the engine starts, gradual fade to zero. At idle with a bunch of stuff turned on (lights, wipers, heater blower) you may see it go as low as -20. You'll see a blip to + and fade to zero once you get moving.
.
Normal gauge behavior is slight or a bit more to the + side after cranking and the engine starts, gradual fade to zero. At idle with a bunch of stuff turned on (lights, wipers, heater blower) you may see it go as low as -20. You'll see a blip to + and fade to zero once you get moving.
Melting Slicks
Joined: Oct 2007
Posts: 2,702
Likes: 192
From: Northwestern Connecticut
St. Jude Donor '10 thru '26
Will a c2 amp gauge pulse with the turn signals like a c1 with a generator? Just curious as I’m looking at a charging issue today and noted that my 63 amp gauge doesn’t move with the turn signals blinking like my 62, but since the 63 has an alternator I was not sure if that might react faster.
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
Thread Starter
Drifting
Joined: Aug 2014
Posts: 1,633
Likes: 135
Did you do the 1.5 volt battery test just to the gauge or from end to end? End to end, which is from the black/white wire at the horn relay to the black/white wire at the starter solenoid, will check the entire meter circuit. Be sure to disconnect the battery for that test.
.
Normal gauge behavior is slight or a bit more to the + side after cranking and the engine starts, gradual fade to zero. At idle with a bunch of stuff turned on (lights, wipers, heater blower) you may see it go as low as -20. You'll see a blip to + and fade to zero once you get moving.
.
Normal gauge behavior is slight or a bit more to the + side after cranking and the engine starts, gradual fade to zero. At idle with a bunch of stuff turned on (lights, wipers, heater blower) you may see it go as low as -20. You'll see a blip to + and fade to zero once you get moving.
Melting Slicks
Joined: May 2001
Posts: 2,749
Likes: 776
From: Dadeville AL
When you start with a known configuration and a single problem, it's fairly easy to diagnose from afar. But with a butchered wiring harness, it's hard to know where to start, other than to suggest an entirely new wiring harness for safety's sake if nothing else.
Last edited by kellsdad; Oct 9, 2022 at 07:55 PM. Reason: Typo
Team Owner
Joined: Feb 2003
Posts: 54,106
Likes: 9,421
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
Well wire nuts do not belong anywhere close to a cars electrical system. It’s time to save headaches and just buy a new plug and play OEM harness. They are fairly easy to replace
Le Mans Master
Joined: Nov 2015
Posts: 7,464
Likes: 2,644
From: Really Central IL Illinois
With the car NOT running, did you turn on the headlights, hit the brakes, turn on the ignition and the heater fan. The battery gauge should go to the negative side with these loads, if the gauge has the correct connections.
Team Owner
Joined: Jul 2006
Posts: 22,183
Likes: 4,178
From: Kannapolis NC
For the battery gauge to read charge or discharge, the key doesn't even need to be on. BUT, there must be a wire (black/white) connected to the red wires on the horn relay, AND a wire (black) connected to the RED positive wire on the starter solenoid. Those two wires connect to the battery gauge connections. They pass through the bulkhead connector.
There should be a pink wire running from the starter solenoid (R connector) to the positive side of the coil (same place the pink wire from the ballast connects).
There should be a pink wire running from the starter solenoid (R connector) to the positive side of the coil (same place the pink wire from the ballast connects).
Race Director
Joined: Apr 2005
Posts: 11,274
Likes: 2,136
From: Bowling Green, Kentucky
The wires for each electrical side of the gage go thru the firewall bulkhead electrical connector block. If the electrical connectors in the block get corroded a bit, the gage will not respond.
You can:
1. Locate and disconnect the inputs to the amp gage back in the engine compartment and try the 1.5 volt battery test from that point.
2. Check resistance of each of the two leads from engine compartment back to gage connector in the dash.
3. Pull apart the firewall connector block that has these two wires running thru it and clean the terminal connections. There are two firewall connector blocks, but only one of them contains the amp gage wires.
Larry
You can:
1. Locate and disconnect the inputs to the amp gage back in the engine compartment and try the 1.5 volt battery test from that point.
2. Check resistance of each of the two leads from engine compartment back to gage connector in the dash.
3. Pull apart the firewall connector block that has these two wires running thru it and clean the terminal connections. There are two firewall connector blocks, but only one of them contains the amp gage wires.
Larry
Melting Slicks
Joined: May 2001
Posts: 2,749
Likes: 776
From: Dadeville AL
stefuel,
Here's a W.A.G. based on your description of the "modified" engine compartment. If it now has an internally regulated alternator and the wiring was changed to bypass the OE voltage regulator, that would be a good place to start. Folks sometimes take power from the new alternator directly to the buss at the horn relay, and that would bypass the BATT gauge.
Here's a W.A.G. based on your description of the "modified" engine compartment. If it now has an internally regulated alternator and the wiring was changed to bypass the OE voltage regulator, that would be a good place to start. Folks sometimes take power from the new alternator directly to the buss at the horn relay, and that would bypass the BATT gauge.
Thread Starter
Drifting
Joined: Aug 2014
Posts: 1,633
Likes: 135
I won't get a chance to look at it again until Wed. This is not a A/C car. Not even a nice one when new. Something else I noticed while adjusting up the new parking brakes. Unless it's totally blown out, it doesn't even have Posi. I don't ever recall working on a C2 that didn't have a posi rear end. Not saying they didn't make them, I just never saw one.
Team Owner
Joined: Feb 2003
Posts: 54,106
Likes: 9,421
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
I won't get a chance to look at it again until Wed. This is not a A/C car. Not even a nice one when new. Something else I noticed while adjusting up the new parking brakes. Unless it's totally blown out, it doesn't even have Posi. I don't ever recall working on a C2 that didn't have a posi rear end. Not saying they didn't make them, I just never saw one.
Last edited by Nowhere Man; Oct 11, 2022 at 05:46 AM.
Le Mans Master
Joined: Feb 2014
Posts: 8,914
Likes: 5,461
From: Richardson Texas
