Truck was slow to turn over, but it started. Next weekend, same thing, but when I got back, I pulled the cables and cleaned them, and put the battery on the charger. Truck would not turn over. Replaced the battery, same result, Not turning over. Turned on the lights, fan, turned the key, everything stayed on, not turning over. I checked the starter relay, looked fine, but swapped it with the same relay from an adjacent spot, nothing.
Not sure what to check at this point. Starter looks semi accessible, I'm going to get under there and tap on the solenoid, but after that, I'm stuck.
Where the positive cable runs into the fuse box, the fuses all look fine.
What next?

 

Check to make sure the wire going to the starter is free of corrosion. If corrosion detected, clean the cable ends and re-try. If still no start, might be time for a new or rebuilt starter.

 

Thanks. I noticed the connection to the starter is a bit rough, the plastic cover has degraded with age, But, today the rain had let up, and I checked the battery voltage at the battery, then again and the fuse box behind the battery. where the aux battery cable connects, no voltage there, with key on or off. Not sure why, the cable runs right off the battery.

 

Bad cable, or bad connection.

 

Have been checking out this starter issue. As I said, the starter doesnt engage, solenoid doesn't click, lights do not dim when trying to crank the engine over. I went to check the voltage at the starter, and found voltage from the battery, but Ive never seen this type of connection before. what is this? This one has been spliced in at some point. Is this a fuse of some type, and could it be the issue?