Battery Drain
Racer
Joined: Jan 2020
Posts: 470
Likes: 147
From: Va.Beach Va.
You blew the fuse in your meter. Unless you have an inductive amp clamp handy your meter will be on Volts Dc or Ac only while the engine is running for testing. Amp current testing is engine off key out doors closed for a basic look. There's a lot going on there for your first time using your meter in more ways than just volts. Your meters max current load appears to be 200mA. Less than a quarter of 1 amp. You need a better meter for sure. Look at a Fluke 115 current spec is 10 amps
Racer
Joined: Jan 2020
Posts: 470
Likes: 147
From: Va.Beach Va.
Another handy feature the 115 has in the min-max-avg setting for current and volt testing. Say you believe there is drain in your car and when testing your may have 15mA and it appears ok. Use the the min max setting and let the meter record over night and it will record the lowest, highest and average (the most important spec) and you find in the morning a 500mA drain as one example. And you were not crazy. Or your testing with the meter and need another hand to turn the key while you watch the meter. With min max you wont need help.
Thread Starter
Racer
Joined: Feb 2010
Posts: 261
Likes: 0
From: St. Louis Missouri
Good morning,
I replaced the alternator and voltage regulator. Getting a clean 13.5 amps on the battery terminals. However the gauge on the dash goes crazy and when I turn on the lights it is all over the place. Any quick check you can think of?
I replaced the alternator and voltage regulator. Getting a clean 13.5 amps on the battery terminals. However the gauge on the dash goes crazy and when I turn on the lights it is all over the place. Any quick check you can think of?
Melting Slicks
Joined: Mar 2005
Posts: 2,093
Likes: 297
From: Midlothian VA
The dash gauge (you don't say which one but guessing you're referring to the amp meter if it's original) yields much info if you know what you're looking at.
WHEN does the gauge "go crazy"? Which "lights"?
Is the engine on or off when you turn on the lights?
If off - then expect the amp meter to go negative/left when your turn on the headlights - this shows that a draw is being made on the battery = discharge.
If on - then prior to turning on the "lights" the meter should read positive (=charging) more so right after starting the engine. Once the battery is topped off the gauge will read "JUST" right of center.
Anytime you turn on the "lights" (especially the headlights) you'll see the gauge go left a bit if during the charge up period right after starting the engine until the battery is satisfied.
With the engine running and the ALT working you should almost never see a discharge/negative reading on the amp meter.
If you do that indicates something is wrong with the charging system.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
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
Le Mans Master
Joined: Jan 2001
Posts: 6,711
Likes: 1,371
The following will help identify if the leads to the ammeter have an intermittent OPEN. Not really specific whatever lights are causing the ammeter to go crazy, but it's a good check to do anyway.
Find the lead going from the horn relay to towards the starter and perform a wiggle test for the lead and the following components. If the ammeter stops working, or stops "going crazy", then you have probably identified the faulted area:
1. Hand-over-hand track it towards the wiper motor....
2. Somewhere around the wiper motor area there should be a node that heads off into the firewall for the ammeter
a. Inspect (wiggle) this connection and fusible link to check if it may have an open.
b. IF it looks questionable then solder in a new fusible link and cover it with heat shrink.
3. Keep following the main lead towards the starter and inspecting.
4. When you get to the starter area, then check the status(wiggle) other connections to this lead. Repair by soldering and replacing fusible links as necessary. Ensure you use heat shrink.
If you do not understand what lead I am writing about, then so state and I will take a picture of the one on my 68.
Find the lead going from the horn relay to towards the starter and perform a wiggle test for the lead and the following components. If the ammeter stops working, or stops "going crazy", then you have probably identified the faulted area:
1. Hand-over-hand track it towards the wiper motor....
2. Somewhere around the wiper motor area there should be a node that heads off into the firewall for the ammeter
a. Inspect (wiggle) this connection and fusible link to check if it may have an open.
b. IF it looks questionable then solder in a new fusible link and cover it with heat shrink.
3. Keep following the main lead towards the starter and inspecting.
4. When you get to the starter area, then check the status(wiggle) other connections to this lead. Repair by soldering and replacing fusible links as necessary. Ensure you use heat shrink.
If you do not understand what lead I am writing about, then so state and I will take a picture of the one on my 68.
Last edited by carriljc; Aug 29, 2020 at 10:58 AM.
Le Mans Master
Joined: Jan 2001
Posts: 6,711
Likes: 1,371
Are your dash lights, or any other lights for that matter, blinking when you turn them on? Try wiping the rheostat on the light switch a couple of times (rotate several times) --- maybe you're having intermittent contact there which is affecting your ammeter (just a guess because those are some pretty big swings).
Le Mans Master
Joined: Jan 2001
Posts: 6,711
Likes: 1,371
Another question: Does the ammeter do this if you turn on the lights when the engine is NOT running? The answer may affect the diagnosis because the ammeter response may be associated with engine and/or vehicle vibration.
Le Mans Master
Joined: Jan 2001
Posts: 6,711
Likes: 1,371
Le Mans Master
Joined: Jan 2001
Posts: 6,711
Likes: 1,371
What is the "passenger side lamp cover"? BUT, anywhichway, disconnect the headlamps on the passenger side and set them aside while ensuring the leads are not bare, or grounding, on anything else. Then run the the same tests.
Thread Starter
Racer
Joined: Feb 2010
Posts: 261
Likes: 0
From: St. Louis Missouri
tried it and no results,
I think I am over my head and will take it to my mechanic
thank you very much for helping me try and trouble shoot the issue. Nuts and bolts are easy compared to electrical issues
I think I am over my head and will take it to my mechanic
thank you very much for helping me try and trouble shoot the issue. Nuts and bolts are easy compared to electrical issues
Melting Slicks
Joined: Mar 2005
Posts: 2,093
Likes: 297
From: Midlothian VA
If the problem started after removing the passenger headlight (would have been good to know in your first post) then I'd be checking for a bad or broken ground wire at that headlight.
Seems though you have multiple issues as replacing the alternator/regulator fixed your charging issue.
It appears your amp meter is wildly swinging between charge/discharge on a regular basis (based on your very short video).
I'd check my connections to the new voltage regulator you installed (on a 68 the voltage regulator is on the driver's fender vs built into the alternator)
OR
I'd suspect that the new voltage regulator is sticking/bad (they have a mechanical relay)
Seems though you have multiple issues as replacing the alternator/regulator fixed your charging issue.
It appears your amp meter is wildly swinging between charge/discharge on a regular basis (based on your very short video).
I'd check my connections to the new voltage regulator you installed (on a 68 the voltage regulator is on the driver's fender vs built into the alternator)
OR
I'd suspect that the new voltage regulator is sticking/bad (they have a mechanical relay)
Thread Starter
Racer
Joined: Feb 2010
Posts: 261
Likes: 0
From: St. Louis Missouri
I went back and forth between the two regulators several times. I pulled all the fuses and then tried each with the same results
The new one has wild swings to the plus and minus
The old one does not charge.
I am sending the new one back. I guess the old saying "you get what you paid for" works here.
I will try another one.
Thanks for all of your help.
The new one has wild swings to the plus and minus
The old one does not charge.
I am sending the new one back. I guess the old saying "you get what you paid for" works here.
I will try another one.
Thanks for all of your help.