Need help ! Electrical failure
Thread Starter
Cruising
Joined: Mar 2018
Posts: 13
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Need help ! Electrical failure
Greetings , I have a 74 vette with basically new everything . New engine , trans and every single engine component has been replaced with new . I was driving at night a few days ago , and all of the sudden my headlights started to go dim and pulsate as if the AC current from the alt was directly impacting the function of the lights . In the cab , the radio began to also turn on and off in one second intervals . Being an electrician , I can’t believe this has gotten the better of me . And suggestions ? The headlights still raise , but are off and every second or two coke on very dim . You can feel it pulsate if you leave your hand on the switch . So odd ….
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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check your grounds on your battery to frame. How does it start, is it labored or does it fire right up? How are the grounds on the engine to frame? IF those look good take an ohms reading across them end to end. A few folks have had the cables corrode under the covers and not be able to detect it. How much voltage are you getting out of the alternator and is the battery seeing the charge?
Racer
Joined: Jan 2020
Posts: 470
Likes: 147
From: Va.Beach Va.
AC voltage present is simple to check for. With all loads on and RPM around 1200-1500, meter set to AC volts anything over .5 volts ac would show the alternator is defective. But it appears your circuit breaker in your head light may be tripping?. If you have a mechanical regulator maybe its going south or as Rescue Rodgers says about checking for ground issues and or voltage drops.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,210
Likes: 9,349
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
You may just want to take the alternator out and have it checked at a good electrical shop. You may have a internal short or something
Thread Starter
Cruising
Joined: Mar 2018
Posts: 13
Likes: 0
check your grounds on your battery to frame. How does it start, is it labored or does it fire right up? How are the grounds on the engine to frame? IF those look good take an ohms reading across them end to end. A few folks have had the cables corrode under the covers and not be able to detect it. How much voltage are you getting out of the alternator and is the battery seeing the charge?
The vette starts right up
Thread Starter
Cruising
Joined: Mar 2018
Posts: 13
Likes: 0
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,210
Likes: 9,349
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
maybe have them test it. If the car starts right up then its getting power and your battery is getting a good connection. You dont want to let it go too long like this as it might fry some of the older components.
Thread Starter
Cruising
Joined: Mar 2018
Posts: 13
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i suppose the good news is 90% of the car has been replaced . The alt , starter , radiator , water pump , tan clutch , engine , trans you name it . I don’t wanna fry anything else . I figured if it was the Alt it wouldn’t have the ***** to charge the car . But it hasn’t died yet . Very interesting . I have a video of what’s going on but I can’t post it here . Apparently it’s too long
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Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,210
Likes: 9,349
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Subsxribe to youtube. Its free. Then upload it there and make it public accessible no age restriction. Once you do that, play the video and copy the link in the header and post it here...easiest way i found to do it.
I had an alternator fry from over revving. I guess they arent happy over 6500 rpm. Maybe thats how yours died......
I had an alternator fry from over revving. I guess they arent happy over 6500 rpm. Maybe thats how yours died......
Thread Starter
Cruising
Joined: Mar 2018
Posts: 13
Likes: 0
Subsxribe to youtube. Its free. Then upload it there and make it public accessible no age restriction. Once you do that, play the video and copy the link in the header and post it here...easiest way i found to do it.
I had an alternator fry from over revving. I guess they arent happy over 6500 rpm. Maybe thats how yours died......
I had an alternator fry from over revving. I guess they arent happy over 6500 rpm. Maybe thats how yours died......
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Lots of new parts come from the factory already broken. Newness has little to do with reliability these days, it seems.
What was your voltmeter doing while your lights were pulsing? Do you have a 1 or 3 wire alternator?
Please post some photos in the meantime! As @Rescue Rogers stated, YouTube plays nicely with the Forum if you can create an account and post videos there.
What was your voltmeter doing while your lights were pulsing? Do you have a 1 or 3 wire alternator?
Please post some photos in the meantime! As @Rescue Rogers stated, YouTube plays nicely with the Forum if you can create an account and post videos there.