High voltage, keeps burning inline fuse from battery to alternator

Does it blow with the key off or just with the ignition on? Blows instantly or after some time?

 

May have some salt or acid creep going on underneath somewhere creating a minor ground at one of the main terminal or battery connections at the starter or battery or elsewhere

 

I had this happen to a car once when the alternator gave up. I think it just shorted out the fuse link.

 

I'm suspecting there's a pretty bad short to ground on that wire or something its connected to.

 

alt can under charge or over charge. when going bad

 

Volts don't blow fuses, amps do.

 

For major electrical, I would let a shop diagnose it. Have them SHOW you what they find before they fix it. You get a problem fixed, and you learn a bit more about the truck.

Electrical problems can cascade rapidly into very nasty, very expensive truck-wide clusterforks. The line from the alternator to the batteries might not normally be connected to other parts of the wiring harness, but damaging the batteries or improper grounding of wires can lead to damage to other parts of the wiring harness or any number of electronic sensors and gizmos.

 

Thank you for this, most don't get that if they don't understand how it works or how to use a voltmeter, then let a pro figure it out, it is worth the money instead of having a truck burn to the ground.