| Re: Electrical issues [message #370834 is a reply to message #359689] |
Fri, 16 December 2022 13:03   |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma:
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Senior Member |
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Seems like most rebuilt alternators these days have a 14.7V regulator. When I tried to buy a replacement regulator, everyone stocked 14.7V units. It maybe Ok for vehicle that just runs around town doing errands and short trips, but we drive for hours at a time. So I ordered a 14.3V regulator.
In the GMC, the 3 wire alternator has a remote voltage sense. This is good for our application because the Isolator has a 0.7V drop across it, plus some voltage loss in the main wire from the alternator. The regulator through the remote voltage sense wire will try to maintain 14.7 volts at the main power feed to the Ignition switch etc.
So 14.7V + 0.7V = 15.4V (plus wire losses) = 15.5V at the output terminal of the alternator. So if that is where you are reading the alternator voltage, that's likely about right.
The High Speed position on the dash HVAC system gets its power from the center terminal of the isolator and takes advantage of the higher voltage here.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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