Alternator not charging, need help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mysticclam · 11-24-2002, 10:56 PM

I just completed converting a '79 diesel silverado to gas, diesel was bad, put an olds 307 in. The battery wasnt charging, looked like it was the alternator that came with my junkyard engine. I put the old diesel alternator on, not charging, only showing battery voltage while running. I put a one wire alternator on thinking Id messed up the charging circuit while cutting out some diesel specific wiring. It wouldnt charge. Bought a new standard 3 wire GM alternator after testing the connector and put it on and still not charging. Truck has two batteries, both brand new. Ive tried having just one batter hooked up, didnt make a difference. Alternator case reads a ground.
Bat cable reads 12 volts so i know its hooked up. The wires going to the #1 and #2 posts on the alternator read show 12 volts all the time for one and 12 volts with the ignition switch on for the other. Its driving me nuts cause the 1 wire wouldnt work, it really sounds like the alternators have no ground but they do. Also, shouldnt one of the wires on the connector read less voltage? I have a volt gauge and no charge light that i can find so im not sure how the #1 and #2 wires should work. Doesnt oen go through the light?
Any input would be appreciated.

Prerunner1982 · 11-24-2002, 11:45 PM

you might aquire a manual and check the wiring schematic... make sure all wires are there and if not, run new ones.

jon

ElGracho · 11-25-2002, 01:19 AM

Take a look at this ....

http://www.oldengine.org/unfaq/10si.htm

mysticclam · 11-29-2002, 08:30 PM

Well, everything I can possibly think of checks out ok. All the wires in the charging circuit are there, doing what they should. I wired up a charging circuit from scratch with a light (truck has a volt gauge) It didnt work either, light stayed on indicating a fault, which I already knew there was. Made sure the belt was tight, cables tight, connections tight, made sure the alternator case was grounded well. Still wont charge. I put the batter on a charger and it seemed to take a charge plus its new, plus i put a different new battery in so I ruled that out. (Batter never got below 11.5 volts so i wasnt trying to charge a dead battery with the alternator) I am going to take 3 alternators to the parts store for testing this weekend. Maybe by some freak of nature they are all bad (2 are new!) Im sure the field isnt energizing but i cant figure out why not!

mysticclam · 12-01-2002, 06:16 PM

Figured out the problem! On my engine, the power steering pump belt goes around the pump, crack and fan. Alternator belt goes around the fan and alternator. The power steering belt was the one that was loose! Alternator charges fine and there are no longer any noises when i turn the steering wheel close to the stops. I dont have a smog pump on right now but its belt goes around the crank and fan too. If id had put that back on i would have realized what was going on sooner.

11-25-2002, 01:19 AM	#3
ElGracho Gentleman Jim Driver Join Date: Nov 2002 Location: Poulsbo, WA Posts: 1,550	Take a look at this .... http://www.oldengine.org/unfaq/10si.htm __________________ Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed

11-24-2002, 10:56 PM	#1
mysticclam Registered User Join Date: Nov 2002 Posts: 3	Alternator not charging, need help! I just completed converting a '79 diesel silverado to gas, diesel was bad, put an olds 307 in. The battery wasnt charging, looked like it was the alternator that came with my junkyard engine. I put the old diesel alternator on, not charging, only showing battery voltage while running. I put a one wire alternator on thinking Id messed up the charging circuit while cutting out some diesel specific wiring. It wouldnt charge. Bought a new standard 3 wire GM alternator after testing the connector and put it on and still not charging. Truck has two batteries, both brand new. Ive tried having just one batter hooked up, didnt make a difference. Alternator case reads a ground. Bat cable reads 12 volts so i know its hooked up. The wires going to the #1 and #2 posts on the alternator read show 12 volts all the time for one and 12 volts with the ignition switch on for the other. Its driving me nuts cause the 1 wire wouldnt work, it really sounds like the alternators have no ground but they do. Also, shouldnt one of the wires on the connector read less voltage? I have a volt gauge and no charge light that i can find so im not sure how the #1 and #2 wires should work. Doesnt oen go through the light? Any input would be appreciated.

11-24-2002, 11:45 PM	#2
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	schematic.... you might aquire a manual and check the wiring schematic... make sure all wires are there and if not, run new ones. jon __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

11-29-2002, 08:30 PM	#4
mysticclam Registered User Join Date: Nov 2002 Posts: 3	Well, everything I can possibly think of checks out ok. All the wires in the charging circuit are there, doing what they should. I wired up a charging circuit from scratch with a light (truck has a volt gauge) It didnt work either, light stayed on indicating a fault, which I already knew there was. Made sure the belt was tight, cables tight, connections tight, made sure the alternator case was grounded well. Still wont charge. I put the batter on a charger and it seemed to take a charge plus its new, plus i put a different new battery in so I ruled that out. (Batter never got below 11.5 volts so i wasnt trying to charge a dead battery with the alternator) I am going to take 3 alternators to the parts store for testing this weekend. Maybe by some freak of nature they are all bad (2 are new!) Im sure the field isnt energizing but i cant figure out why not!

12-01-2002, 06:16 PM	#5
mysticclam Registered User Join Date: Nov 2002 Posts: 3	Figured out the problem! On my engine, the power steering pump belt goes around the pump, crack and fan. Alternator belt goes around the fan and alternator. The power steering belt was the one that was loose! Alternator charges fine and there are no longer any noises when i turn the steering wheel close to the stops. I dont have a smog pump on right now but its belt goes around the crank and fan too. If id had put that back on i would have realized what was going on sooner.



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