It seems like every time I try to help my truck, it gets mad at me. Sunday I replaced my o2 sensor, changed my oil, and cleaned my iac valve. I disconnected the battery before I did any of the work (both pos and neg cables) so the computer would reset after. Once I finished everything and connected the cables I fired the truck up and it runs great, drives fine, and I've driven it about 30 miles since then, however my battery light is still on. It came on when I started it the first time, and the voltage gauge reads at 8 volts on the dash (however it usually hung around 10 anyways, my gauges are always off)

I figure if the alternator conked out that the truck would have died by now, driving in town and a little highway with the radio and my subs going. I used a voltmeter on it yesterday and the battery still reads 12.14 volts when the truck is running, and 12.3 volts with the truck shut off. But I pulled off the positive battery cable while it was running and the truck shut off. Unless these trucks are weird, that shouldn't happen. I use that trick to change batteries without losing radio and other presets in other cars. I hooked it back up and started it, still runs fine but the light is still on. All the cables near the battery including the ground near the radiator seem good and tight too..

Do you guys have any ideas??

 

Your alternator is prob bad...just yank it off and take it in to any parts store and they can check it for you. Alts can do that sometimes, diodes probably went bad. If all your connections look good and are tight chances are thats what it is.

 

but if its the alternator, the battery wouldn't be able to recharge. And the battery seems to be charging fine. Could the alternator go bad and send a bad signal while still recharging the battery?

 

Fixed it. I feel dumb for not noticing it now, but when looking at replacement alternators online I saw there are one and two plug alternators. Mine is a two plug and only the one plug on top connected to the voltage regulator was connected. The plug on the bottom of the alternator was disconnected, and I overlooked it thinking there was only one. Hooked it back up, light is gone. The connection must have gotten knocked loose when I pulled off the battery cables. So you were definitely on the right track farmer12. Thanks

 

Actually to your other post....if your alt is charging right you will have 13.5 to 14 volts at your battery. If its 12 with the motor running its def not charging.

 

yea, I should have thought of that. I just saw the 12, thought it was normal and went on my merry way. Careless mistake. Thanks for the help, who knows how long it would have taken me to notice it was undone if you hadn't said anything.

 

Glad it got handeld man. My I had to put a altanator in my 87 and dang is was agervating at first but ran into the same prob as you with the bottom plug. I forgot it also. Realized after i cranked it though.