Security light on why?

You will need to scan it for codes, must be a stored code for the security system. Other thing you might check is all fuses and connectors. Associated with ignition and security.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://youtu.be/YV3TRZwer8k

This sounds like the cluster is the issue. However, we should start with checking for codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once we know if there are codes or not we can jump into the cluster issue.

Basically the way this works is these systems all run through or are displayed through the cluster. The fact that the security light is on but the vehicle still starts, or the battery light is on and the alternator appears to be working shows that the actual systems are not the issue. It is most likely the cluster itself.

Let us know and we can go from there. Thanks

So if you changed the engine you would have changed the ECM over from the other engine as well, correct? If you did this then the keys that you are using is still for the other engine control module.

I suspect the only way we are going to fix this is getting generic PCM with the theft system deleted off of it so that when it gets the ignition switch feed that it is not looking for a specific signal and it just starts the engine.

This is pretty common when we do an engine swap and these services are pretty common. In fact, I suspect you can find one where you just send you PCM off and they will remove the theft system and send it back.

If you take a look at the information below you will see how the system works.

Let us know if you have questions. Thanks

Hi,

Did you have the battery disconnected when you unplugged the PCM? Also, if you leave the key in the on position for approximately 10 minutes, does the security light turn off?

Check pin 16 in the DLC to see if there is power present. See the attached pics.

Let me know what you find.

Joe

Hi,

I should have asked this earlier, but can you confirm the engine size? The 4.8L doesn't exist on this vehicle. If you look at the attached picture, it shows what I am seeing. I need to confirm the correct engine to really dig into the wiring schematics. Pin 16 is a standard power supply. That's why I was able to get this far.

Also, if you disconnected the PCM without having the battery disconnected (disconnected or reconnected), it could have caused damage to the PCM.

Let me know.

Joe