Strange charging issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chrismoore701 · 06-22-2020, 12:56 PM

I have a 79 c10? Strange issue with my alternator. I swapped out my heater core yesterday and it stopped charging while running. Measured voltage off the single post on alternator and it measured 11.7v. Took it in and they said it measured good. Putting out over 14 volts. Could i have popped a fuse by snagging a wire under the dash?
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Pontiac1976 · 06-23-2020, 02:25 AM

Did you test it when it was running to get that 11.7v . Or did you test the batt.( running not running) To see what volts you got for both. check your fuses step 1 and your ground @ the fan motor and or firewall. One screw should make a connection to the fan body( no paint under the head of the screw then that screw should transfer to the firewall body, if has the one brass spade ground. The other spade with the rubber would be +.
If your connections are good. And your batt still under 12.5 it maybe not holding a charge.

06-22-2020, 12:56 PM	#1
chrismoore701 Registered User Join Date: Dec 2004 Location: Highland, IN Posts: 2,326	Strange charging issue I have a 79 c10? Strange issue with my alternator. I swapped out my heater core yesterday and it stopped charging while running. Measured voltage off the single post on alternator and it measured 11.7v. Took it in and they said it measured good. Putting out over 14 volts. Could i have popped a fuse by snagging a wire under the dash? Posted via Mobile Device

06-23-2020, 02:25 AM	#2
Pontiac1976 Registered User Join Date: Oct 2015 Location: Ottawa, Ontario, Canada Posts: 769	Re: Strange charging issue Did you test it when it was running to get that 11.7v . Or did you test the batt.( running not running) To see what volts you got for both. check your fuses step 1 and your ground @ the fan motor and or firewall. One screw should make a connection to the fan body( no paint under the head of the screw then that screw should transfer to the firewall body, if has the one brass spade ground. The other spade with the rubber would be +. If your connections are good. And your batt still under 12.5 it maybe not holding a charge. __________________ 1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.



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