I'll try this again. My 93 F350 460 has a headscratcher issue. All of the sudden it won't start. I can put a different battery in it and as soon as I connect it the voltage on that battery starts dropping. There will be power to the gauges but as soon as you turn the key it clicks and then there's zero power, no lights no gauges nothing. The other day I tried jump starting it and it kept doing that cycle, I'd have power and then when I turned the key I'd loose all power again for awhile. It wouldn't start until I wiggled the battery cables then it started I let it run awhile and then it wouldn't restart. I have removed the battery cables and using a multimeter and having the cables on a battery on the bench I have tested them and they seem fine. I would appreciate any help please as I have never dealt with this type of issue.

The positive cable has a small wire with a female clip that runs with it and clips on a tab on the starter--can someone tell me what that wire does? My other trucks only have the bigger cable to starter.
thanks

 

You either have a poor main battery cable connection or a main ground connection. OR possibly a bad battery cable that is shorting internally. It sounds like you had the main cables off and tested them but there is a lot more juice going through them when you try to start the engine.

So if all your main connections are clean and tight and the cables are good you shouldn't lose all power when trying to start the engine. I don't think the problem is in the starter area or you wouldn't lose all power.

I have experienced the lose all power deal many times over the years and I almost always found the problem to be where the battery cables hook onto the battery posts.