STARTER WON'T STOP - 1988 Ford F 250

What engine do you have?

There could be a problem with the starter, or the battery.
But neither one will cause the vehicle to stop running.

solonoid is mounted on top of starter, they work together. under the engine, sure its not your key switch ?

have u check if there in sprek

could be a problem starter relay or starter solenoid
if the battery lead goes straight to the starter , pull the starter and have it bench tested

If the engine won't fire up, but your starter turns over, you may want to check your timing unless you have a check engine light on. If the CEL light is on, have the codes scanned.

If the engine won't turn over with the starter or it clicks, have your battery tested at autozone or advanced auto parts. Replace the battery if it is bad. Else, have your starter tested.

If the engine still won't turn over and the battery and starter are tested fine, you may have a blown fuse, bad ignition switch, or a failed relay.

If the engine fires up but randomly dies and starts back up, you either have a failed sensor, failing fuel pump, clogged fuel filter, bad plugs or wires, or a failing ECU.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

The security system does not disable the starter, it only disables fuel to the engine. In the fuse block under the hood, locate the STARTER relay. Place your hand on this relay and see if it clicks while someone else turns the key to start...if the relay is ok then the starter itself is faulty. Good luck, i hope this helps.

week or bad battery
bad starter

When a battery is very low, even a jump won't work because the battery takes too much out of the jump. Take the battery out and have it charged up.
If it won't take a charge, get a new one.
But also make sure the battery terminals and cable ends are shiny and greased.

If you really want to be sure, put a voltmeter on it.
A good battery should be 12.5.
When you crank it should go down to about 10.
If it goes below 9, either the battery is too low, or the starter is draining too much.
If it never goes below 11, it is not draining enough, and the solenoid is probably bad.
If when you stop cranking, it comes back up to over 11, then the battery is good, so the starter is probably bad.