What could be the problem?

[rodalt02]

I had ECM rebuilt and I installed along with a new ACLV and TPS. Now car will not start. Rebuilder says that the keys shouldn't have to be reprogrammed since it is still original ECM. Car will turnover but not catch. The only thing I have noticed is that my security light comes on and stays on when I try to start the car. Could I have done something to the ACLV or TPS when changing them or does a rebuilt ECM need to be reprogrammed? Any help will be appreciated. Thanks.

[loystock]

Most likely the NATS key ID info was wiped out from the ECM during refurbishing. The Security LED must turn OFF when Ignition Switch is at ON position provided both the IMMU (Ignition Lock Cylinder) and the ECM detect the correct NATS keys ID. Any mismatch will cause the LED to remain ON even with ignition at ON.

You need to bring all the car keys when the ECM is reprogrammed at the dealership.

The Security LED is also controlled the Smart Entrance Control Unit, part of the Vehicle Security system. But it's mainly for car alarm.