I replaced the alternator because I had a "charging system failure" message on the info panel, and the battery is testing good. Now, the battery is dead in the morning when I try to crank it up. Once I put a jump charger on the battery, it starts immediately. Something is pulling the battery down after 4-6 hours.
If I run around town after I jump it off, it cranks right up. Only when I leave it for several hours does it lose it's charge.

 

Did you do a load test on the battery? Just a voltage check won't do it. Take the battery in to a Napa or some place like that that sells batteries and tell them of your problem. Just don't mention the new alternator! Doesn't mean there is not a voltage draw, just eliminates the battery. And if the battery checks out ok, drive the truck for a day, disconnect the battery over night (like on a Friday night, reconnect it on Saturday and see if it starts right up. If it does, start pulling fuses and to from there. Good luck!

 

Yes. It has been load tested at Napa and Walmart, out of the vehicle. I'm just wondering if that new alternator could actually charge while running, and have a "leak" while not running. That is the only part changed since this problem started, and it started immediately (next morning) after replacing alternator.

 

Take the alternator to NAPA and have them test it. Check the wiring exiting the alternator......esp. the wire going to the battery. Bucko is big on not using reman alternators, for what that is worth. Or pull the plug from the alternator overnight and see if that is the fix.

 

The alternator tested ok on the "in vehicle" test at the auto parts store. Does it seem possible that an alternator can charge while running, and yet, cause the battery to discharge due to a short in the alternator while not running? i.e. change the replaced alternator?

 

Anything is possible. That is why I suggested pulling the alternator connector overnight, especially after you know the battery has a good charge prior to disconnecting the alternator. Why did you change the alternator to begin with?

 

I replaced the alternator because I had a "charging system failure" message on the info panel and the battery tested good.

 

I replaced the alternator again this evening. Only took about 40 minutes this time. The morning will tell the tale. However, I just went out (3 hours since replacement) and the battery is steady at 12.6 volts (not cranked).
Fingers crossed.

 

You should have used your money on a battery not another new altenator. If the altenator has a short inside of it would charge.

 

Alternators only supplies charge to the battery and as well as powering all of the electronics in your vehicle. A bad alt would not cause it to drain the battery as it does not pull any current from it. It would help us if you could please list any aftermarket electronics etc.