I put a new solenoid in and went to start the motor. The starter ran continuously with the key off. I overrode the solenoid and tried hooking the ground to the engine, and I touching the positive cable to the positive terminal cable to the start, and it acted like it was reverse polarity, with no batteries hooked up, or even in the vehicle. It arced really bad. If batteries are in the vehicle and I go to hook cables, it arcs really bad. I double-checked to make sure they weren't backwards, which they were not. What could be causing my arcing problem?
It sounds like either the solenoid or the starter are wired up incorrectly. If the signal wire to the starter is connected to 12v, then the starter will turn. Double check your solenoid wiring to be sure that it is correct. The solenoid probably has 3 or four connections- one for incoming cable from battery, one for outgoing power to starter, one connection for a signal wire from the ignition or start switch, and sometimes there is a ground connection as well.