Will not start I think it is the security system

Well you might just need to run the relearn procedure. I'm attaching some images that I pulled off of the web. They are a set of instructions for relearn procedures for all of GM's theft deterrent systems. Run the one for whichever Passkey iteration that you have (probably the original Passkey) and we'll go from there.

Thanks for using 2CarPros. Good luck and let us know anyways.

Harry

Welcome to 2CarPros.

I believe this is an easy fix. What you described sounds like a weak connection at the battery. Make sure the terminals are clean and tight.

Take a look at this link:

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

Let me know if that helps.

Joe

If everything goes dead, similar to having no battery in the vehicle, follow the smaller battery positive wire to the under-hood fuse box and be sure that connection is clean and tight. Follow the smaller negative battery wire to the body and be sure that one is tight and not rusty.

Rather than reposting the same problem multiple times, please stick to this one until we get this solved. I can get other experts involved if we need bigger brains.

The stuff going dead might be a misleading clue. Things like the heater fan, radio, and wipers get turned off in the "crank" position by the ignition switch. That switch might be out of adjustment just enough that the rod isn't moving it quite far enough to hit the last contact for the starter system. To check for that, look for 12 volts on the yellow wire at the ignition switch when it's in the "crank" position.

If you do find 12 volts on the yellow wire, feel if the starter relay is clicking when a helper turns the ignition switch. If it is, the neutral safety switch is the best suspect. This is the first time I've seen a starter circuit with a relay and the neutral safety switch is in the relatively high-current starter solenoid circuit. There can be 10 - 15 amps flowing through the ignition switch and neutral safety switch. That is asking a real lot of the neutral safety switch, and it makes a relay pointless. Try cranking the engine after moving the shift lever around the "neutral" position.

If you have 12 volts on the yellow wire and the relay does not click, this is an anti-theft system problem as others have suggested.

I thought we were working on a cranking problem. We need to know where a voltage is missing to figure out which circuit we need to diagnose.

Things can happen when a scanner is connected. Fords of that era are much worse. All kinds of things happen on those as the scanner puts the computer through a series of initial tests to see how it responds.

Yes, it could definitely be a weak connection there. Stop at the local parts shop and grab a new terminal. It's probably $3. Pop it in and see what happens. Also, have you tried wiggling the shifter back and forth while holding the key in the "crank" position? What about cranking it with the shifter in neutral?

And yes, it's normal for the fan to run while you have the car in diagnostic mode.

Yep that will do it. here is a guide to help walk you through the steps for changing the starter:

https://www.2carpros.com/articles/how-to-replace-a-starter-motor

Please let us know what happens.