High voltage issue
Thread Starter
Cruising
Joined: Mar 2017
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High voltage issue
I have a 1974 454 Vette that I just got running after sitting for 25 years. I have had the car running for about 5 months now until last week I ran into an issue. The radio was cutting in and out during high rpms. After checking it out the car was running at 18 plus volts. So I replaced the alternator and still high volts. So I removed the alternator completely and still high volts. So I ran a new positive wire and new ground wires. It is still over 18volts. I replaced the ignition switch and no luck there. I replaced the starter and still high volts. Im at a stand still. I need help on where to go next. Please help.
Drifting
Joined: Jul 2011
Posts: 1,697
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From: Syracuse NY
If you removed your alternator and ran the car, Id assume its IMPOSSIBLE to get more than 12 volts as your battery would be your only source of electricity. With the alternator removed, where did you check voltage?
Last edited by Scottd; Mar 9, 2017 at 09:07 PM.
Le Mans Master
Joined: May 2003
Posts: 8,874
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
18 volt without an alternator- Then I think your meter is bad. There is no way you'd see that- even if you were running a 16Volt race battery....
Radio cutting in and out- - IF the alternator WAS putting out that high a DC voltage- the radio would play louder....AND your instrument lights will be really bright.
Back in the days when I was in the Car stereo industry- a couple of unscrupulous dealers would run the voltage up on the power supplies to make the radios and amps on display sound better!!!
IF the alternator was putting out AC voltage ( bad diodes) THEN the radio would cut out.
Richard
Radio cutting in and out- - IF the alternator WAS putting out that high a DC voltage- the radio would play louder....AND your instrument lights will be really bright.
Back in the days when I was in the Car stereo industry- a couple of unscrupulous dealers would run the voltage up on the power supplies to make the radios and amps on display sound better!!!
IF the alternator was putting out AC voltage ( bad diodes) THEN the radio would cut out.
Richard
Thread Starter
Cruising
Joined: Mar 2017
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I checked the voltage at the battery and at the alternator connections with my multimeter (alternator is not hooked up) and its reading 18volts plus.
The radio is an aftermarket one that has a surge protector in it. It was installed in the car way before I had this issue. I even unplugged the radio completely and I still have a high volts.
Could a power wire be touching the frame cause the volts to up up like this?
The radio is an aftermarket one that has a surge protector in it. It was installed in the car way before I had this issue. I even unplugged the radio completely and I still have a high volts.
Could a power wire be touching the frame cause the volts to up up like this?
Le Mans Master
Joined: May 2003
Posts: 8,874
Likes: 3,551
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
NO-
A fully charged battery will be about 12.6 volts
If the car is not running- the alternator will not be charging- there is no way you will see anything more than 12.6V
If the car is running and the alternator is charging you should see 13.7 to 14 volts.
If a "hot" wire was touching the frame - you'd see smoke.
Take the meter to another car and read the voltage- if it says 18V- then you have a bad/inaccurate meter.
Richard
A fully charged battery will be about 12.6 volts
If the car is not running- the alternator will not be charging- there is no way you will see anything more than 12.6V
If the car is running and the alternator is charging you should see 13.7 to 14 volts.
If a "hot" wire was touching the frame - you'd see smoke.
Take the meter to another car and read the voltage- if it says 18V- then you have a bad/inaccurate meter.
Richard
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Thread Starter
Cruising
Joined: Mar 2017
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I have an HEI distributor installed, could that be leaking voltage into the system? The voltage at the battery is high too (18 plus). And I checked the meter on another car and it was reading fine. I'm going to get my dads meter today to try that one too.
Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
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The 74's have an ammeter.
The HEI-to the spark plugs is AC voltage...
Race Director
Joined: May 2006
Posts: 18,665
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with the ignition switch in the ON position but the engine not running
disconnect the two wire plug on the side of the alternator, note the numbers 1 and 2 on the alternator.
connect the red voltmeter lead to the plug at the #1 wire and ground the black voltmeter lead. If you get zero voltage move the wire in the plug to see if there is a partial break at the connector. If you still get zero voltage piece the wire further down with the voltmeter probe and see if you get a reading. If you do the connector is bad and should be replaced. Do the same thing with the #2 wire in the plug.
disconnect the two wire plug on the side of the alternator, note the numbers 1 and 2 on the alternator.
connect the red voltmeter lead to the plug at the #1 wire and ground the black voltmeter lead. If you get zero voltage move the wire in the plug to see if there is a partial break at the connector. If you still get zero voltage piece the wire further down with the voltmeter probe and see if you get a reading. If you do the connector is bad and should be replaced. Do the same thing with the #2 wire in the plug.
Thread Starter
Cruising
Joined: Mar 2017
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Ok update. So I found the issue. My dad told me to put the old points distributor back in the car to (Humor)him. So I did and we are back to a normal running system. So my question is what is the HEI distributor doing then. Why is it bleeding volts into the system.