Just as the title states, I can run the truck by jumping the posts on the solenoid, but not by turning the key. For some reason the small wire that activates the solenoid isn't doing it's job. For reference it's an F150 4.9L manual 4spd.

What powers that wire that excites the solenoid? Where does the wire come from? I tried tracing it but I lost it and i really don't want to unravel the whole harness. This is the only thing holding me back from driving the truck tonight after it being down for two months, any help would be greatly appreciated! Thanks in advance!

 

The power to that little wire comes from the ignition switch when it is held in the START position. If you run a jumper from that little post that that little wire hooks on to the large solenoid post farthest from the battery, will the engine spin over?

 

I think the start wire goes through the clutch switch too. Something else to check, at least.

 

do you get power to everything when the ignition is on?
if you do just run a couple wires to a push button

 

Well I found the problem guys, thank you for the responses.

It turns out that the main ground that bolts to the frame before going to the block was totally corroded and mangled. I made up a replacement for that, still no fire. Then I pulled the starter (again, I had just done the clutch which sucked badly) bench tested; she tested fine, I cleaned all connections including the mounting points to get a good ground; still nothing.

So finally I said screw this, took a battery terminal straight from the positive and ran it to the starter..... WE HAVE IGNITION! So I made up a new wire from solenoid to starter and everything is gravy now.

I suppose being in there and disturbing things just made the wires that were on their last legs go bad.

Again thanks for the advice!