took the alternator off and had it tested the machine said all was good.. checked the fuse and its still good just replaced it a couple months ago.. but it still wont charge the full 14v it stays right around the low side on the gauge (8v)... any ideas?

 

Do you have 12 V to the back of the alt? ( big red wire ) if not you may have blown the 150 amp fuse in the underhood fuse block. Need to know that first.

 

Other than that the pcm determines the needed rate of charge. That you would need some sort of scanner to diagnose. Does the tach work? Crank sensor can cause a similar problem too.

 

The fuse is new and looks fine. yes the tach works like normal. i'll test the red wire and see what i got

 

change the batteries... Mine went downhill and wouldn't hold a charge, I got some walmart batteries and its back to normal. I thought it was somthing else like a fuse or the alternator, but it worked thankfully just changing the batteries.

 

Grr it better not be the batteries they are only like 3-4 months old.... but they've been hooked to a charger before and leaked a bit so that could be possible. Can you check and refill a wal-mart battery? They're yellow not sure what brand..

 

More than likely either a power to the alt prob, or a pcm prob. Batteries should be charged before doing any pcm testing though.

 

how do you test the pcm?

 

You have to have a scan tool. Start easy though. Do you have 12 v at the back of the alt? Start there. Belt is on and the alt is turning right? Sorry have to ask!

 

Lol yes the belt is on... i'm not sure on the 12 at the alt yet truck isn't here at the moment. will check that first, then buy a new fuse, then try batteries, then i guess the wonderful pcm... sound like a good plan?

 

If they are yellow walmart batteries they are Everstart aka-neverstart. They have a 2 year warranty. I take mine back about every 18 months.

 

I'd rather see you do some checking before throwing parts at it. Check for voltage #1, then you may have to pay someone to do a diagnostic check on it if all else fails, but at least you would be money ahead of just putting new parts on.

 

I had issues with my 2000 and the alternator a few months ago. Had 2 problems actually. One turned out to be the alternator's diodes, that was fixed and every once in a while it wouldn't be reading low voltage on the gauge. My 2 wire connector on the alternator also gave me a bunch of grief, had to tweak the pins so it made better contact.

I don't know what style alternator is used on a 97, but if it has a push on connector and not the stud and nut, its something worth looking at.

 

it has the stud and nut type but i been thinkin it has something to do with that... gonna see what i can get done with it today i'll let yall know what i find

 

The same thing happen to me on my truck about 3 years ago same exact symptoms when I installed the mystery switch to lock up the torque converter I removed the connector on the back of the PCM to tap in to the the wire grounding wire. Well the wire that controls the voltage regulation had a bad crimp and came loose which caused the alternator not to charge. I can't remember what wire it was off hand but it's worth pulling the connector and checking the wires for continuity. I can look in my manual as to which wire it is but I won't be able to get back to you till Monday, I'm going out of town.