First off I am just a shadetree mechanic at best. Wife was driving truck and had one of the batteries go bad on her in town. She was able to get jump started and to a mechanic who replaced battery. Started like a charm....until. Next day truck wouldn't start for her, already knew I needed a positive battery cable so I picked one up to replace it. When at home I noticed the interior lights not working and it sounded like the flashers were trying to run but were not. Replaced battery cable at this point and now....I GOT NOTHING. No lights, no radio, no horn, nadda. Any ideas for this dumb hillbilly besides having to haul it 30 miles to someone actually qualified to figure it out?

 

One scenario that fits your description is that one (or more?) of your alternators went bad, and the new - fully charged - battery was able to run your vehicle for an hour or so even though the alternator wasn't charging it. The point is, that in this scenario, your alternator is bad, which means the new battery won't totally fix your problem.

However, either you're going to have to get a $20 voltmeter, or you're going to have to drive your alternator to a car parts shop for load testing, or truthfully, there's not much help the internet can offer. I.e., you can't "see" and diagnose electrical problems without some minimum equipment so we can communicate!

 

Single alternator and the O'Reilly's where my wife was able to take it at the time supposedly tested it and said that it was good.

 

Batteries should always be replaced in pairs, first off. You need to get the batteries out, completely charge them and then load test them with a battery load tester.

Check all your connections, battery terminals and ground connections to make sure they're all good and tight and clean.

Then, with a volt meter attached to one of the batteries, you need to check the battery voltage with the key off, with the key on but not started, while cranking, just after starting and after it has idled for a few minutes.

 

This is true for the diesels, but the OP didn't state which engine he has.

 

Replaced one battery last year, would have replaced both then if financially able. Checked both batteries and both fully charged, all connections clean and tight. Cannot start, will not crank therefore my total fustration.

 

Sorry, 7.3 powerstroke.

 

hi

maybe check fuses, relay and check near the fuses box that someone cut any wires trying hook up a remote starting or light and not connect them right

 

No crank, no lights, no horn, nada, but two "fully charged" batteries. I doubt all the fuses blew. Maybe if the 7.3 has a fusible link?

I would start by measuring one of the batteries positive pole against the chassis somewhere. Then also check for good voltages in various places in and around the fuse box, as well as the starter relay.

 

7.3 also have ground cables that like to come loose. They go the the engine block at the bottom front of the engine.