Altenator/ charging issue.. FRUSTRATED! help!

toeknee567

New Member
May 5, 2010
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So the end of last season before i parked my 89 notch 5.0, 5 speed, I was having an intermittent problem. When i was driving at night my volts would drop sometimes and my lights would go dim.. and id hit a bump or hit the gas and volts would come back and lights would be bright. So anyway I parked it, knowing i would have to deal with it in the spring. Well its SPRING! So I jump the car... and wiggle some wires... its not charging.. eff it.. i go get a new altenator... hook it up...still not charging... ( now mind you I had 2 autozones check my OLD alt and said it was bad.) After the new alt didnt work I had a 3rd place check my old alt and said it was good.. HMMMM ANYWAY.. So i put my old alt back in.. and im back at square one. I wiggle my battery and some wires and boom the volts are back up. so I quickly drive the car from storage to my house and park it. its a half hour drive and it was at night.. lights were bright... volts were high. this was 2 weeks ago. So i put the car on the road all happy about driving to a local car show today and i hop in.. start it up and volts are in the red... i spent hours wiggle wires and strippin battery cables and puttin on new terminals.. tried a diff battery... i took out the volt meter and measured batt to chassis, batt to motor batt to every ground i could find... batt to alt... alt was puttin out 12.6v i spent hours chasin wires cleaning connections..checking with a volt meter.. im ready to pull my hair out... should i try a new alt again ??? i dont get why it would come on and off like a switch... i would swear its a bad wire or ground.. but it starts up fine just the battery wont charge... the alt says its putting out the volts... but im also no electrician... what can i check ?? it was intermittent before 2 weeks ago but today i couldnt get the volts to come back at all.... any ideas would be much appriciated... this is my daily driver now.. so i need it solved quick!
 
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When it acts up, tell us what the system voltage is while at 1500 RPM. It should be at least 13.6 volts. Do the same test with your lights and HVAC fan on.

While it acts up, check the regulator values. The wires are labeled A, S, I. With the car running, A should be the same as battery voltage, S should be about 1/2 battery voltage, and don't worry about I.