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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: LegoChevy on April 23, 2015, 09:32:50 am

Title: 1980 k10 new alternator
Post by: LegoChevy on April 23, 2015, 09:32:50 am
I just replaced the alternator on my truck and it will not charge. Had it tested and it tested good. I bought a new battery thinking the battery was junk. I can't figure out why it won't charge. It was fine one day bad the next.
Title: Re: 1980 k10 new alternator
Post by: LegoChevy on April 23, 2015, 09:33:59 am
If anyone has any tips tricks or info on what could be wrong I would greatly appreciate it.
Title: Re: 1980 k10 new alternator
Post by: blazer74 on April 23, 2015, 01:31:14 pm
Loose connection someplace, bad wire.
Check connections on starter and junction block on firewall.


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Title: Re: 1980 k10 new alternator
Post by: enaberif on April 23, 2015, 05:50:34 pm
What is the voltage across the terminals when the truck is running?
Title: Re: 1980 k10 new alternator
Post by: Irish_Alley on April 23, 2015, 11:39:11 pm
i made the mistake once of not hooking the battery wire back up to the back of the alternator (http://www.naioa.com/v2/modules/Forums/images/smiles/eusa_whistle.gif)
Title: Re: 1980 k10 new alternator
Post by: LegoChevy on April 27, 2015, 05:11:54 am
I checked all wires replaced the starter and argued with the guys at O'Reillys for half hour because I was set on my NEW alternator being junk. I got fed up with them went to advance and bought a new alternator and bam. Fixed. But thanks to you guys I did figure out my starter was about shot and a wire on that junction block was hanging by a thread. Even after all that fixed it was still reading somewhere in the neighborhood of 11.1 or so on my tester and somewhere around 9ish on my dash gauge. Thanks for the help guys!!   :D
Title: Re: 1980 k10 new alternator
Post by: enaberif on April 27, 2015, 07:03:09 am
11.1 when running is low and way out of spec. You should be seeing high 13s into the low 14s when the truck is running. You either have ground issues, wiring issues or a bad battery or alternator.
Title: Re: 1980 k10 new alternator
Post by: LegoChevy on April 27, 2015, 07:34:20 am
I replaced the alt with a new one agaiN now its doing just fine. the guys at O'Reillys kept telling me my truck was junk that the alternator was good. Which now I know it wasn't my truck lol