66 Caprice voltage fluctuation
April 26th, 2022, 11:12 AM
#1
CF Beginner
Thread Starter
66 Caprice voltage fluctuation
First let me apologize for the length of this post. I want to be sure that I’m giving you all of the details regarding my problem. Feel free to ask any clarifying questions – I’ll be more than happy to answer as best as I can. Any advice is appreciated. There may be a thread that already exists regarding this specific problem, and if so, feel free to send me there.
I just bought a 66 Chevy Caprice from a private seller. The car is really nice and very happy with it. But there is a problem that has me stumped in the electrical system. When I first test drove the car, I noticed that the voltage was running high. It looked like around 16 volts at the gauge. My first guess was that the regulator was bad so after I bought the car, I replaced it. It was a standard brand, and after installing it, I noted that nothing had changed. Test voltage at the alternator and battery were both at almost 17 volts. Since I knew nothing about the alternator, I decided to get an OE replacement just so that I knew exactly what I had in there. So I bought a rebuilt Delco-Remy 63 amp alternator and installed it. No change – the voltage at the alternator and at the battery was still almost 17 volts. In talking to a buddy of mine who has a 67 Impala, he happened to mention that the ground might be bad to the regulator. He said that the regulator grounded to the frame (radiator support). I remembered that the two bolts holding on the regulator were insulated by rubber grommets, and saw that I could add another bolt in a third hole provided on the radiator support which was not insulated with a grommet. So I put one in and voila! The voltage came down to a more normal level. Problem solved? Well not quite.
There is a fluctuation in the voltage at idle and when running down the road. It jumps from about 13.5 to 14.5 and I can see the lights getting brighter and dimmer as the voltage fluctuates. No clue what might be causing this, but there are a couple of things that could have something to do with it. First, my dash lights are really dim. The switch itself seems to work to a point – I can turn down the brightness and that works, but the dome lights don’t work when I switch them on. I’m wondering if there might be something messed up in the switch that would cause this fluctuation. Any ideas would be welcome. Second, the gen light will go on at a certain idle speed but goes off when you rev engine or when the idle is lower (around 800 rpm). It also whines a little at the alternator when the light is on, but that goes away when the light goes off - at running speed or lower idle.
Finally, I noticed that some of the bulbs are missing (glove box, trunk) and I'm not sure if that could cause a connection issue or not. I'm not very electrically inclined, I just know some basic stuff.
Thanks in advance for your help
I just bought a 66 Chevy Caprice from a private seller. The car is really nice and very happy with it. But there is a problem that has me stumped in the electrical system. When I first test drove the car, I noticed that the voltage was running high. It looked like around 16 volts at the gauge. My first guess was that the regulator was bad so after I bought the car, I replaced it. It was a standard brand, and after installing it, I noted that nothing had changed. Test voltage at the alternator and battery were both at almost 17 volts. Since I knew nothing about the alternator, I decided to get an OE replacement just so that I knew exactly what I had in there. So I bought a rebuilt Delco-Remy 63 amp alternator and installed it. No change – the voltage at the alternator and at the battery was still almost 17 volts. In talking to a buddy of mine who has a 67 Impala, he happened to mention that the ground might be bad to the regulator. He said that the regulator grounded to the frame (radiator support). I remembered that the two bolts holding on the regulator were insulated by rubber grommets, and saw that I could add another bolt in a third hole provided on the radiator support which was not insulated with a grommet. So I put one in and voila! The voltage came down to a more normal level. Problem solved? Well not quite.
There is a fluctuation in the voltage at idle and when running down the road. It jumps from about 13.5 to 14.5 and I can see the lights getting brighter and dimmer as the voltage fluctuates. No clue what might be causing this, but there are a couple of things that could have something to do with it. First, my dash lights are really dim. The switch itself seems to work to a point – I can turn down the brightness and that works, but the dome lights don’t work when I switch them on. I’m wondering if there might be something messed up in the switch that would cause this fluctuation. Any ideas would be welcome. Second, the gen light will go on at a certain idle speed but goes off when you rev engine or when the idle is lower (around 800 rpm). It also whines a little at the alternator when the light is on, but that goes away when the light goes off - at running speed or lower idle.
Finally, I noticed that some of the bulbs are missing (glove box, trunk) and I'm not sure if that could cause a connection issue or not. I'm not very electrically inclined, I just know some basic stuff.
Thanks in advance for your help
April 26th, 2022, 12:30 PM
#2
CF Monarch
First let me apologize for the length of this post. I want to be sure that I’m giving you all of the details regarding my problem. Feel free to ask any clarifying questions – I’ll be more than happy to answer as best as I can. Any advice is appreciated. There may be a thread that already exists regarding this specific problem, and if so, feel free to send me there.
I just bought a 66 Chevy Caprice from a private seller. The car is really nice and very happy with it. But there is a problem that has me stumped in the electrical system. When I first test drove the car, I noticed that the voltage was running high. It looked like around 16 volts at the gauge. My first guess was that the regulator was bad so after I bought the car, I replaced it. It was a standard brand, and after installing it, I noted that nothing had changed. Test voltage at the alternator and battery were both at almost 17 volts. Since I knew nothing about the alternator, I decided to get an OE replacement just so that I knew exactly what I had in there. So I bought a rebuilt Delco-Remy 63 amp alternator and installed it. No change – the voltage at the alternator and at the battery was still almost 17 volts. In talking to a buddy of mine who has a 67 Impala, he happened to mention that the ground might be bad to the regulator. He said that the regulator grounded to the frame (radiator support). I remembered that the two bolts holding on the regulator were insulated by rubber grommets, and saw that I could add another bolt in a third hole provided on the radiator support which was not insulated with a grommet. So I put one in and voila! The voltage came down to a more normal level. Problem solved? Well not quite.
There is a fluctuation in the voltage at idle and when running down the road. It jumps from about 13.5 to 14.5 and I can see the lights getting brighter and dimmer as the voltage fluctuates. No clue what might be causing this, but there are a couple of things that could have something to do with it. First, my dash lights are really dim. The switch itself seems to work to a point – I can turn down the brightness and that works, but the dome lights don’t work when I switch them on. I’m wondering if there might be something messed up in the switch that would cause this fluctuation. Any ideas would be welcome. Second, the gen light will go on at a certain idle speed but goes off when you rev engine or when the idle is lower (around 800 rpm). It also whines a little at the alternator when the light is on, but that goes away when the light goes off - at running speed or lower idle.
Finally, I noticed that some of the bulbs are missing (glove box, trunk) and I'm not sure if that could cause a connection issue or not. I'm not very electrically inclined, I just know some basic stuff.
Thanks in advance for your help
I just bought a 66 Chevy Caprice from a private seller. The car is really nice and very happy with it. But there is a problem that has me stumped in the electrical system. When I first test drove the car, I noticed that the voltage was running high. It looked like around 16 volts at the gauge. My first guess was that the regulator was bad so after I bought the car, I replaced it. It was a standard brand, and after installing it, I noted that nothing had changed. Test voltage at the alternator and battery were both at almost 17 volts. Since I knew nothing about the alternator, I decided to get an OE replacement just so that I knew exactly what I had in there. So I bought a rebuilt Delco-Remy 63 amp alternator and installed it. No change – the voltage at the alternator and at the battery was still almost 17 volts. In talking to a buddy of mine who has a 67 Impala, he happened to mention that the ground might be bad to the regulator. He said that the regulator grounded to the frame (radiator support). I remembered that the two bolts holding on the regulator were insulated by rubber grommets, and saw that I could add another bolt in a third hole provided on the radiator support which was not insulated with a grommet. So I put one in and voila! The voltage came down to a more normal level. Problem solved? Well not quite.
There is a fluctuation in the voltage at idle and when running down the road. It jumps from about 13.5 to 14.5 and I can see the lights getting brighter and dimmer as the voltage fluctuates. No clue what might be causing this, but there are a couple of things that could have something to do with it. First, my dash lights are really dim. The switch itself seems to work to a point – I can turn down the brightness and that works, but the dome lights don’t work when I switch them on. I’m wondering if there might be something messed up in the switch that would cause this fluctuation. Any ideas would be welcome. Second, the gen light will go on at a certain idle speed but goes off when you rev engine or when the idle is lower (around 800 rpm). It also whines a little at the alternator when the light is on, but that goes away when the light goes off - at running speed or lower idle.
Finally, I noticed that some of the bulbs are missing (glove box, trunk) and I'm not sure if that could cause a connection issue or not. I'm not very electrically inclined, I just know some basic stuff.
Thanks in advance for your help
April 26th, 2022, 12:58 PM
#3
CF Beginner
Thread Starter
Is the voltage regulator separate, original configuration? Is it point regulator, it has contact points under the cover, or has it been upgraded to electronic? It sounds like to regulator is set too high, or points (if it has points) are sticking. Take a pix, post it. If it has the original point regulator, upgrade it to an electronic one.
This is a solid state regulator. external from the alternator. So no points to adjust. I know what you are referring to, though. My friend has a 67 Impala and his has the adjusting screw that lets you change the setting. Mine doesn't even let you take the cover off - all solid state.
April 26th, 2022, 3:02 PM
#4
CF Monarch
Hi Kevin - thanks for the quick reply!
This is a solid state regulator. external from the alternator. So no points to adjust. I know what you are referring to, though. My friend has a 67 Impala and his has the adjusting screw that lets you change the setting. Mine doesn't even let you take the cover off - all solid state.
This is a solid state regulator. external from the alternator. So no points to adjust. I know what you are referring to, though. My friend has a 67 Impala and his has the adjusting screw that lets you change the setting. Mine doesn't even let you take the cover off - all solid state.
April 26th, 2022, 3:35 PM
#5
CF Beginner
Thread Starter
Last edited by pete_from_tx; April 26th, 2022 at 3:39 PM. Reason: added picture
April 27th, 2022, 1:37 PM
#6
CF Beginner
Thread Starter
So the problem turned out to be the regulator itself. I got a bad one. Apparently from what I have read, that's not uncommon and others have complained about the same issue when they bought a new regulator. The Delco-Remy and Standard brands had the most complaints oddly enough. So I stopped at O'Reillys and picked up another. Just popped it in now and it's working fine.
So you were right on, Kevin. Thanks for your help on this!
So you were right on, Kevin. Thanks for your help on this!
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