2001 ford f350 ABS light came on

If you can't find out the reason, get scanned the computer of your car for a disgnosis

First thing to do Is plug it in 6.0ltrs hate the cold second check glow plug circuit if you don't have a block heater you need one a coolant circulator is the best but if its really cold a heater on the oil pan a swell

Have the charging system checked. Autozone, Advance, and Oreilys will do it free. Check Diodes.

Some production years had a weird problem. Its worthy of mention but since you replaced the batteries, it should not apply. Watch your Charge, Voltmeter as sometimes the Alternator will disconnect automatically WHILE DRIVING at even 70mph. The system monitors your vehicle for PARASITIC drains and automatically disconnects the power connection as part of a Battery Saver.

So if Battery levels fall, causing the Alternator to work too hard to recharge a drained system, it will disconnect the charging circuit. Even if if you used a boost to jump the truck, it will charge for maybe 5 minutes and then disconnect.

Now for the battery to drain in 1 hour, you should have a glowing part. About the only thing which could drain that much power is a Rear window defroster or a stuck timer or power relay on the glowplug system.

The glowplugs could be remaining energized and you would not know it. A grounding starter could drain the system. Have a draw test performed.

Most anything else would break a fuse or burn a wiring connection.

Clean the Negative battery cable and if mounted to the block, check the engine to frame strap.

Please rate my info.

https://www.fleet.ford.com/maintenance/owners_manuals/results.asp
here

very normal with a 7.3 to be hard starting at lower temps the only thing i can recommend is getting a remote start with cold start where it starts it every 2 hours and runs it for 10 mins other than that you need to plug it in

The charging system (alternator ) is not working ! Your best bet would be to take it to a qualified repair shop

I had the same problem with my 2003 Ford Explorer. I disconnected the battery, which give the relays a chance to reset.
Clean battery termals reconnect and all good.

if the wire is plugged into the box you may have to install a fuse to make the line hot.

It sounds like the engine is running on battery power only.The engine of today`s technology needs the alternator to have enough ignition to run on,lights and computer,etc,will be affected by low voltage,and amps.The alternator is not charging,look for a charging fuse to see if it is blown.If the fuse is fine,replace the alternator,and have the battery recharged on a slow 2 amp charge so it will recover it`s loss of deep cycle amps.This will prolong battery life and alternator.If I can help let me know.Let me know the out come.

actually the only thing i can recomend is to have the alternator replace again for warranty and before starting the truck charge the batteries very well with a baterie charger make sure to charge them individually because with a low batterie the alternator has to put a lot of load and might burnt again
specially with dual batterie.