Truck won’t start

Is the security light flashing or just on? If it is just one this is normal, I would check the battery cables and if okay. Let's use a test light to test the trigger wire at the starter solenoid. This guide can help us get started to fix the problem. It sounds like the starter has gone bad.

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

Here is how to change the starter out in case you need it. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

I’ve had the starter checked and they said it’s still good.

When the key is in the crank position does the trigger wire have power? if not, I would swap out the starter relay here is the location and the starter wiring diagrams so you can see how the system works. Check out the images (below). Please let us know what happens.