Ammeter ?
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
The “S” terminal is from the ignition switch.
Even though it means something else when the vehicle has a warning light, I remember it as S stands for “switched“ and that helps me remember that the green with red wire on the S post gets power from the ignition switch.
This is what triggers the alternator.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
OK now I have nothing on the SAT term on the alt, battery power on the alt batt terminal and swithced 12V going to the GN/RD term on the VR S term. It's charging all right, @ 18V when running. VR is grounded and I'm going to run a wire from VR ground to the ground term on the alt.
Should be 14 to 14 1/2 V, but 18 V either means that something is still out of whack, or the regulator is faulty. Try the other regulator.
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Trailering
Joined: Sep 2014
Posts: 19
Likes: 0
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Trailering
Joined: Sep 2014
Posts: 19
Likes: 0
I did a couple of things, a couple of loose connections, and for grins and giggles I started it up again, and voltage was at 14.7. I'm calling it fixed, but of course, I will keep a check on it.
Cargo Master
Joined: Mar 2008
Posts: 2,573
Likes: 207
From: Washington
Car LED Digital Voltmeter, DC 12V Cigarette Lighter Voltage Meter, Volt Gauge Battery Monitor, Digital Voltage Display for Auto Car Truck
https://a.co/d/fiLEId1
I bought one of these, very helpful to have.
On a side note, your current choke power source is HOT KEY ON.
So don't leave the key on in the winter time. Start the engine, if you leave the key ON for a few minutes, before starting, it will pull the choke open, and it might not start.
This issue was often fixed by running the power though a oil pressure switch.
After market market carbs used a relay, trigger by the stator output of the alternator.
Obviously it has been working OK as is, just something to be aware of.
Jim
https://a.co/d/fiLEId1
I bought one of these, very helpful to have.
On a side note, your current choke power source is HOT KEY ON.
So don't leave the key on in the winter time. Start the engine, if you leave the key ON for a few minutes, before starting, it will pull the choke open, and it might not start.
This issue was often fixed by running the power though a oil pressure switch.
After market market carbs used a relay, trigger by the stator output of the alternator.
Obviously it has been working OK as is, just something to be aware of.
Jim
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Trailering
Joined: Sep 2014
Posts: 19
Likes: 0
Well.....
I thought all was well till I went out this morning to a dead battery. Checked all the lights and ign switch and everything was off. Remembering to always go back to the last thing you did, I took the wire from the batt to the VR and no parasitic drain. I hooked it back up and I have a 3.7 amp drain. Is it time to change the regulator after all? Oh, I didn't rum a ground from the VR to the alt yet, but I'm going to right now. I honestly don't think that will make any difference, but it;\'s worth a shot and needs to be done anyway.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Definitely worth a shot. Even though it probably won’t do anything for this regulator, it might give the next regulator longer life.
Or at least the charging system a better chance.
But yes, I would tend to agree that if you unplugged the regulator and the drain went away, it’s the regulator.
If it was a failing diode array in the alternator itself, I believe the drain would remain even after the regulator was removed from the equation.
Or at least the charging system a better chance.
But yes, I would tend to agree that if you unplugged the regulator and the drain went away, it’s the regulator.
If it was a failing diode array in the alternator itself, I believe the drain would remain even after the regulator was removed from the equation.
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Cargo Master
Joined: Mar 2008
Posts: 2,573
Likes: 207
From: Washington
I thought all was well till I went out this morning to a dead battery. Checked all the lights and ign switch and everything was off. Remembering to always go back to the last thing you did, I took the wire from the batt to the VR and no parasitic drain. I hooked it back up and I have a 3.7 amp drain. Is it time to change the regulator after all? Oh, I didn't rum a ground from the VR to the alt yet, but I'm going to right now. I honestly don't think that will make any difference, but it;\'s worth a shot and needs to be done anyway.
This would be similar to a "full field test". Similar to the 18 volts you saw. The 2 things seem related to me.
Normally I don't support random part changes, but I would toss the voltage regulator in the trash and used to new one from here on out.
Jim
Last edited by JimsRebel; Nov 29, 2025 at 01:41 PM.
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Trailering
Joined: Sep 2014
Posts: 19
Likes: 0
Definitely worth a shot. Even though it probably won’t do anything for this regulator, it might give the next regulator longer life.
Or at least the charging system a better chance.
But yes, I would tend to agree that if you unplugged the regulator and the drain went away, it’s the regulator.
If it was a failing diode array in the alternator itself, I believe the drain would remain even after the regulator was removed from the equation.
Or at least the charging system a better chance.
But yes, I would tend to agree that if you unplugged the regulator and the drain went away, it’s the regulator.
If it was a failing diode array in the alternator itself, I believe the drain would remain even after the regulator was removed from the equation.
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