Brand New Alternator Wont Charge Batteries.

[TwoStrokes]

I just bought a 96 7.3 from a guy who has owned it for a while. He said he changed out his altenator after his battery light came on and his batteries no longer held charge. After installing two new batteries and a new altenator the new batteries still don't charge.
A buddie of mine said this happend to his 93 Cummins a while back and he had to order some computer chip to repalce the one that had fried on his truck.
I don't know if that would be the same for a Ford but if it is and if anyone has heard of this or has any other suggestions on why the new altenator wont charge new batteries, any input would be appreciated. I would like to know what the part is called so I can order it at Ford without having to bring it into the shop.
thanks,

[Snake]

If I understand correctly, the seller said he changed the alternator and the batteries before he sold the truck to you. Any idea where he bought the alternator?

[ryandamo]

never heard of replacing a computer chip on fords. anyways there is a good chance the guy lied to you and the batteries may be older then they appear, best thing to do first is get them load tested then work from there

[TwoStrokes]

Oh yeah I forgot. The check engine light comes on too because the alternator isn't charging the batteries. I am only going off of what the guy said.
I actually havent even seen the truck. A buddie of mine told me about it cause I was complaining about how I sold my old 7.3 a couple years ago and I wanted another one.
He told me the truck neededs a little work but it only has 150000 km on it.
I don't get home till the end of this month so I don't even really know whats wrong with it.
I just wanted to try and get a head start on ordering parts.

[Snake]

Sounds like an alternator and two batteries are at the top of the list so far.

[bravenight]

On my 7.3 i had to replace my alternator , I also replaced both batteries. I had the same thing happen.What i did was i had to run a new hot wire, that turned hot when the ignition was turned on, the alternator then charged. I used the wiper hot wire. was the shortest and i didn't have to run a wire into the cab.
The only problem I have now is it doesn't put out a charge right away.
and when idle it doesnt put out 14 volts only when i rev it up past 1000 rpm will it then put out a charge, I only run into a problem with this set up is when i have my heater fan on full , and or lights on .
I havent had a chance to take it in to a buddy who deals with auto electric
but if it is a problem i can post and inform my finds, if no problem or finds then i wont post anymore,and i would then say assume things are OKAY

[Michael707]

im having the same problem with my toyota pickup bro. no worries. im sick right now but if i swap out my alternator and my ish still isnt charging ill hop into your boat and be pissed with you lol. but on the upside i just bought a 250 amp dc power alternator for my 96 powerstroke and let me tell you it is the ****! im running close to 7000 watts of amplifier power and i have 2 group 31 batts behind my back seat and two group 34 batts under the hood and my voltage doesnt drop below 13.8 at full tilt no matter how long i play the music