Is my alternator failing?

I would say no on the short, bad connection very possible. The only way to know for sure is see how many amps it is still putting out. It's is likely to be getting weak, also you could have gotten a bad battery. I hate to see a guy spend money if not needed especially with the quality of parts they push on us. The poor mans way of testing the alternator is turn the lights on for 15 to 20 minutes eng off. You only want to take some charge out of batteries not drain them. Start engine let it run for a minute or two. Feel of alt if it's blistering hot it's ok most likely. If you can hold your hand on it it's bad. I know that May sound backwards but to generate power you have to make a lot of heat. If it is not getting hot most likely the brushes are wore some.

 

Yeah ideal voltage is 13.5 eng running. Although it is normal to have to raise the rpms one time to excite most truck alternators.

 

Don't forget to check the short cables that connect them all together. If the cable between the first and second battery is bad then you theoretically only have 1 usable battery.

 

Check output voltage right at the alternator at idle. It should still be around 13.5 volts. If not it needs to be replaced. If a battery is shorting out it will get hot.

 

I just put an alternator on mine, old one ran 14.1, this one is 14.5

 

I was always taught that you must have full batteries to check your alt for charging.

If it were me, I would disconnect the cables and fully charge the batteries. Then clean the terminals and check the cables, including the ground strap.

Then connect cables, start, and check charging.

I think optimal charging is 13.8 to 14.2, but I think up to 14.5 is ok.

I would also use a separate tester (not relying on truck gauge).

Just my .02. Hope it helps.