I have a 99 Dodge Ram 1500 with a 5.9l. I went out to start it and the starter won't turn over.

Are you jumping the two terminals together right on the starter? What exactly do you hear when you try to crank it from the ignition switch?

OHHH! You're jumping the solenoid contacts. That's what the solenoid does internally after it engages the flywheel. You're actually bypassing the solenoid that way so it isn't going to engage; just the starter motor will spin, and your jumper wire is going to have to pass about 100 amps. If you want to jump it that way, you have to jump from the large battery terminal to that brown wire right next to it. That will activate the solenoid to make it mechanically engage the flywheel teeth, then the movable plunger will switch the high-current contacts to activate the motor. The engine will crank that way.

A much easier way is to bypass the starter relay, either by jumping terminals 30 and 87 together or by removing its cover, reinstalling it that way, and squeezing the movable contact.

What exactly is it doing? This page might help:

http://randysrepairshop.net/chrysler-1960---1980s-rwd-operation.html

The entire system can be broken down into three circuits; the low-current ignition switch circuit, the medium-current solenoid circuit, and the high-current starter circuit. If you bypass the starter relay and the starter cranks the engine, that proves the medium and high-current circuits are working and the problem is in the low-current circuit which includes the neutral safety switch.

Thanks, but we haven't solved the problem yet. Did you do the tests on the bottom of the Nippendenso starter test page?

http://randysrepairshop.net/chrysler-1960---1980s-rwd-system-tests.html

Last section, "Quick Tests at the Relay".