starter not working

Welcome to the forum, you need to do testing when the problem occurs. When the problem occurs, are you saying it cranks good but won't start, or it won't even crank?
this guide will help

https://www.2carpros.com/articles/starter-not-working-repair

If it won't crank, I'd have to check the starter circuit. With intermittent issues, you have to test when the problem is ongoing. If you test when everything is working fine, you can't find anything.

Thank you for your rapid reply.
Does an auto mechanic need to test the starter circuit or is there something I can do to check it?

If it refuses to crank, is the theft/security lite on or flashing? Also, there is a starter relay, underhood, driverside fusebox. You can check circuits, there. If no starter action, did you try cranking in neutral?

I have replaced the battery, ignition and starter relays. I had the starter tested and it passed without issue off of the car

Does anything happen when you turn the key to the start position? If there is nothing, I need you to test something for me. Have a helper turn the key to the start position while you check for voltage to the smaller wire on the starter. There should be 12v. If there is, the issue is the starter or the engine is locked up. If there is no power, check for power to the starter relay itself.

Let me know what you find.

Nothing happens when the key is in the start position. There is zero voltage to the smart cable on the starter when the key is turned to the start position. I was able to start the car by jumping the starter with a screw driver.

Correction to wording. There is Zero voltage to the smaller cable when the key is turned to start.

Sometimes I will turn the ignition key and my car will crank and start with no problem and sometimes I will turn the ignition key and the engine will not crank over at all. Its like trying to start a car with the gear selector not in park or a car with dead battery. I bought a new battery and I still have the same problems with it cranking sometime and sometimes not. I don't know if its the starter or alternator.
The lights still come on when the engine doesn't crank over. My car is a 1999 Pontiac Trans Am with a LS1 and I am the original owner, so nothing has been tamoered with. Its all stock and original.

When it doesn't start, I need you to check to see if there is power to the smaller wire on the starter. Also, I need you to make sure the security light isn't staying on.

Let me know what you find.

Okay, the power to the smaller wire comes from the starter relay. Check to see if there is power to the relay.

It can be the starters not getting power or it is going out. But it sounds like to me that your ignition switch is going out. I have a 99 trans am as well and ive gone through the same problem. It starts but sometimes it won't and feels as if the battery is completely dead.

Ok. Of the 4 prongs - 2 of them test with 12+ volts, 1 tests negative 3, and 1 tests at 7.2 volts on the starter relay insert. About The same results at the ignition relay as well.

That is very possible. However, if you check for power to the starter, relay... you will know if the switch is the problem based on where you lose power.

Forgot to mention that those results are with the key in the on position.

My car has had the same issue recently, until it finally would not start at all. The security light is on, but it has been on for years . The starter has been replaced, but now it seems there is no power getting to the new starter. Any ideas?

What happens to the readings when you turn the key to the start position?

96 trans am, wont crank

The first thing i would do is have your battery tested and make sure your battery cables are clean and tight.Do you have a multimeter or test light?