Fluttering ammeter
Thread Starter
Advanced
Joined: Jul 2022
Posts: 89
Likes: 87
From: Scotts Valley, CA
Fluttering ammeter
The ammeter needle in my '71 bounces erratically when the engine's running... sometimes between the halfway points (-20 to +20?), and sometimes beyond. Frequency increases with rpm, but it's pretty rapid even at idle. Bad regulator?
Race Director
Joined: Nov 2006
Posts: 13,151
Likes: 7,764
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Regulator is a voltage regulator. Put a volt meter on the output stud of the alternator, should be reading around 14.5 volts. Then put volt meter right on battery terminals. Should be maybe .1 volt lower than the output at the alternator.
check all battery cables and ground strap from engine to frame. Ground cable under Battery at frame. Etc.
if all good I would suspect bad gauge.
If not all good repair as necessary.
check all battery cables and ground strap from engine to frame. Ground cable under Battery at frame. Etc.
if all good I would suspect bad gauge.
If not all good repair as necessary.
Thread Starter
Advanced
Joined: Jul 2022
Posts: 89
Likes: 87
From: Scotts Valley, CA
Regulator is a voltage regulator. Put a volt meter on the output stud of the alternator, should be reading around 14.5 volts. Then put volt meter right on battery terminals. Should be maybe .1 volt lower than the output at the alternator.
check all battery cables and ground strap from engine to frame. Ground cable under Battery at frame. Etc.
if all good I would suspect bad gauge.
If not all good repair as necessary.
check all battery cables and ground strap from engine to frame. Ground cable under Battery at frame. Etc.
if all good I would suspect bad gauge.
If not all good repair as necessary.
Battery connections are clean and tight, as are both grounds you mentioned. I'll try the voltmeter test. Thanks!
Racer
Joined: Feb 2002
Posts: 378
Likes: 19
Had this going on with my '68. Eventually the source was discovered while driving when the connector to the ignition switch started smoking. Had to get flat towed home.
Not saying that's the problem, with your '71, but would be hesitate to drive it around much with the bouncing amp gauge.
Did you check for loose or bad connections behind the amp gauge?
Maybe, it would not be a bad idea to check whether the ignition switch is getting hot, the key heats up.
Not saying that's the problem, with your '71, but would be hesitate to drive it around much with the bouncing amp gauge.
Did you check for loose or bad connections behind the amp gauge?
Maybe, it would not be a bad idea to check whether the ignition switch is getting hot, the key heats up.
Thread Starter
Advanced
Joined: Jul 2022
Posts: 89
Likes: 87
From: Scotts Valley, CA
Had this going on with my '68. Eventually the source was discovered while driving when the connector to the ignition switch started smoking. Had to get flat towed home.
Not saying that's the problem, with your '71, but would be hesitate to drive it around much with the bouncing amp gauge.
Did you check for loose or bad connections behind the amp gauge?
Maybe, it would not be a bad idea to check whether the ignition switch is getting hot, the key heats up.
Not saying that's the problem, with your '71, but would be hesitate to drive it around much with the bouncing amp gauge.
Did you check for loose or bad connections behind the amp gauge?
Maybe, it would not be a bad idea to check whether the ignition switch is getting hot, the key heats up.
Not yet. On the list.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
When I had a similar issue with my 71 it was the alternator positive stud coming loose. You mentioned battery connections, but for the amp meter I would be looking at the connections at the Starter and Horn Relay.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski