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#1 |
Registered User
Join Date: May 2010
Location: North Babylon New York
Posts: 6
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Still showing 12 volts replaced battery, alternator, starter and battery cables,
getting 12V no matter what idle or accelaration. Changed the fused ling at starter, guess i', just running off the battery just a matter of time. Whwn I purchased the truck it had a differant engine could it be that it it's only should be at 12 volts? was there at one time older trucks ran at only 12 volts? |
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#2 |
Registered User
Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: Still only 12 volts
Are you going by the gauge in the dash or a hand held voltmeter?
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Oscar '72 Shortbed Fleetside '95 Jimmy 4X4 '69 GMC Custom Camper |
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#3 |
Registered User
Join Date: May 2010
Location: North Babylon New York
Posts: 6
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Re: Still only 12 volts
gauge in the dash and aftermarket autometer gauge .
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#4 |
Registered User
Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: Still only 12 volts
Measure the voltage at the battery. With the engine off, it should be 12.7 volts or more. With the engine running it should be 13.5 volts or more. If these measurements are good, the wiring connections between the battery and your instrument panel need to be addressed. Poor ground connections are a common cause of low readings.
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Oscar '72 Shortbed Fleetside '95 Jimmy 4X4 '69 GMC Custom Camper |
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#5 |
Registered User
Join Date: May 2009
Location: Houston, TX
Posts: 155
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Re: Still only 12 volts
check your ground cables and straps.
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#6 |
One shot, one kill.
Join Date: Dec 2007
Location: Saratoga Springs NY
Posts: 859
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Re: Still only 12 volts
Mancuso, Disconnect the alternator. With a test light see if all 3 wires are hot with the key ON. They all should show power. The brown wire should be dimmer than the others. If any of the wires don't show power you found the problem, just backtrack till you find the open. Next hook it back up and start the eng and test voltage right at the alt output lug. As stated above it should be above 13 volts. If not, the alt is bad. I strongly suspect a wireing issue. There are 3 or 4 fuse links in our trucks, check them all. jim
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1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shot ![]() |
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