When I try to start my truck it acts as if it has a dead battery. The battery reads 13.8 volts dc and when I have it running the alternator shows 14.6 volts. I'm scratching my head. Any clues would be helpful. It will start with a jump.

Battery VOLTAGE testing is unreliable - load testing along with specific gravity readings using a hydrometer is the only true way to test a led acid battery. I realize that most DIYer's do not have such testing equipment .. I suspect a failed battery - OR - poor battery cable connections TO the battery post. Jump starting is utilizing the *outer portion* of the battery cable clamps.

What is the battery voltage while cranking ? If less than 9.6 volts either the battery is junk or the starter is pulling too many amps.