Posted this over on another forum also and just wanted a set of fresh eyes and idea's because im stumped. Been fighting this for more than a month now and i dont trust my truck because of it.
Heres my problem...
About 6 months ago i would get a random like once a month "Battery not charging" message on the instrument cluster and the voltage gauge would be sitting at the mark between 9 and 14. I knew that the factory AC Delco batteries were on their way out and one day i went out to just a click from the starter. Replaced the batteries and all was well for the next couple of months.
About a month ago i start getting the "battery not charging" message again on like every cold startup and it would stay on until you revved the engine up then kick off and the voltage gauge would show 14 or just a hair above the rest of the day until it was shutdown and let cooled off all of the way. I replaced the alternator and had the batteries load tested, Batteries load tested good.
So now with known good batteries and the new alternator im no longer getting the "battery not charging" message but voltage still takes like a minute 15 seconds to come off of the 12 volt mark. I have hooked a voltmeter to the batteries and the output of the alternator and confirmed that it isnt just he gauge and that the alternator truely isnt putting out. Start it up and let it run for like a minute 10 second/minute 15 seconds with a volt meter on the back of the alternator and you can watch the voltage come up to 14 or so. Also once it comes up to 14 or just a hair over the voltage gauge flickers around for the next couple of minutes then finally settles at the normal voltage.
Heres a video of the no alternator output, Right after the video ended the voltage went up...
Video
Heres what ive done so far...
Removed and cleaned the 2 grounds on each side of the block in front of the engine mounts.
Remove and cleaned the ground underneath the drivers door hinges on the frame.
Used a volt meter and checked to make sure alternator was grounded good, put positive on output post and negative on alternator case with engine off and had battery voltage.
Put positive lead on alternator output wire in junction box and negative on battery negative then moved positive lead to alternator output stud, Found there was 0.07 difference between directly at the alternator output stud and at the end of the wire/fusible link at the junction box that is connected to the output stud.
Also found out yesterday that if you start it cold the alternator doesnt kick in for like a minute 10/15 seconds like mentioned above BUT if you just turn the key to the run position and let it sit there for a minute or so then start it alternator voltage will come up instantly.
Heres my problem...
About 6 months ago i would get a random like once a month "Battery not charging" message on the instrument cluster and the voltage gauge would be sitting at the mark between 9 and 14. I knew that the factory AC Delco batteries were on their way out and one day i went out to just a click from the starter. Replaced the batteries and all was well for the next couple of months.
About a month ago i start getting the "battery not charging" message again on like every cold startup and it would stay on until you revved the engine up then kick off and the voltage gauge would show 14 or just a hair above the rest of the day until it was shutdown and let cooled off all of the way. I replaced the alternator and had the batteries load tested, Batteries load tested good.
So now with known good batteries and the new alternator im no longer getting the "battery not charging" message but voltage still takes like a minute 15 seconds to come off of the 12 volt mark. I have hooked a voltmeter to the batteries and the output of the alternator and confirmed that it isnt just he gauge and that the alternator truely isnt putting out. Start it up and let it run for like a minute 10 second/minute 15 seconds with a volt meter on the back of the alternator and you can watch the voltage come up to 14 or so. Also once it comes up to 14 or just a hair over the voltage gauge flickers around for the next couple of minutes then finally settles at the normal voltage.
Heres a video of the no alternator output, Right after the video ended the voltage went up...
Video
Heres what ive done so far...
Removed and cleaned the 2 grounds on each side of the block in front of the engine mounts.
Remove and cleaned the ground underneath the drivers door hinges on the frame.
Used a volt meter and checked to make sure alternator was grounded good, put positive on output post and negative on alternator case with engine off and had battery voltage.
Put positive lead on alternator output wire in junction box and negative on battery negative then moved positive lead to alternator output stud, Found there was 0.07 difference between directly at the alternator output stud and at the end of the wire/fusible link at the junction box that is connected to the output stud.
Also found out yesterday that if you start it cold the alternator doesnt kick in for like a minute 10/15 seconds like mentioned above BUT if you just turn the key to the run position and let it sit there for a minute or so then start it alternator voltage will come up instantly.
