Electrical issues with my F150
Or put your battery on a load test, I had a similar problem with one of my older trucks. Went through a starter and almost the whole fuse box and the battery just wouldn't hold a load.
On a battery posts, a corroded or very poor contact can melt the lead on the post or connector from the heat generated passing a couple hundred amps but still be good enough to supply enough power to a minor load like lights etc.
To see this, look at the post and cable connectors for pock mark craters in the lead indicating melting has ocurred.
Always inspect the cables for under insulation problems.
Overall there is not that much to look at so you have to find it.
Good luck.
When you go to crank, the start relay pulls up and closes 'negitive' side of battery to the starter motor. You read it right, the neg side.
If the starter motor is locked up against the flywheel for instance a huge amount to current is drawn.
If there happens to be a poor conection to to boot, the rest of the truck goes without voltage due to the large "voltage drop" that can ocurr across a poor connection due to heating. After all 12 volts times 200 amps is 2400 watts of power as a ball park figure depending on the situation. This amount of heat can do funny things.
So again a voltmeter is not fool proof on such a trouble.
The mega fuse is not in the starting circuit but in series with the alternator so is not likely to act in such a manner.
Mega fuse at 175 amp rateing in not large enough for long term use in a starting circuit.
It's there to protect the truck from fire should the alternator or wiring go shorted to ground.
I just recently had a starter do this, kill all voltage due to the high current drawn at attempted cranking.
Changed starter problem solved.
I don't know what you will eventually find but you have to look at it by how the system works and do all the checks aside from just a voltmeter.
If you want to see the circuit, reference the Haynes book Page 12-17.
Good luck.
I have had a volt meter F**K me over 1,000 times, actually it was me doing the F**King over because I was chasing down a dead end road.
Have the starter tested, I had one, one time, that pulled wAaaayyy to many amps and flipped the main breaker at advance auto when they tested it.





