3GR

Followed Rusty_OToole's suggestion. Went to start the Desoto this morning and on the first attempt the starter failed to stop cranking. Tapped solenoid with both a plastic and a steel hammer several times with no result. Removed the ignition key from the lock and starter continued cranking. Tapped front of the lock lightly with a hammer and that didn't work. Had to disconnect the batter cable to get the starter to stop. Immediately reconnected cable and starter operated normally for 7 tries then started cranking again and I couldn't stop it. Thinking that the problem could be the ignition switch, went to auto parts store and bought a can of Blaster Lock Dry Lubricant & De-Icer. Shoved the spray nozzle into the lock, gave it a good squeeze, and worked the key back and forth several times. Reconnected the battery cable, turned the key back and forth to the start position about 40 times, and each time the starter functioned normally. I guess time will tell if this was the problem. Open to more comments.

Thanks, but already checked for frayed wires.

Good suggestion! I'll give the relay a rap next time it sticks. If it releases I can rule out the possibility of a bad ignition switch.

Have a 1949 Desoto 2nd series (S13). Starter will engage and crank engine, but when key is released starter continues to crank until battery is disconnected. Starter motor is good and engine will start, but starter will not disengage after engine starts. Don't know if it's a starter solenoid issue or if there's a problem with the ignition switch. Tried wiggling the ignition key on and off, but this has no effect on stopping the starter. Have cleaned wire connections on end of solenoid, but this was no help. Also cleaned and lubricated started drive and linkage, but that made no difference. This is an intermittent problem that happens in one of about 25 starts. Can anyone help me troubleshoot this? Have a service manual but it's of little use.