Hello I have a 2002 Monte Carlo SS with a 2004 Monte Carlo SS supercharged motor. When we first put that motor in the car it ran okay for quite a while but then I started having problems the security light would go on and off and multiple other issues with the shifting of the transmission and now it doesn't even start please help. Any suggestions???

 

When you did the engine swap, I assume you swapped the PCM from the donor Monte? And did you also swap the transmission as well?

As for the no start, does it crank? If you leave the key in the on position is the security alert showing in the message center? If so, you could try the PCM Relearn process.
https://montecarloforum.com/forum/fw...hlight=relearn

The anti-theft system in these cars has to do with a chip on the lock cylinder (not the key), the PCM and BCM. Now what I am not 100% sure, if the VIN was not updated in the donor PCM, could that cause an issue, perhaps.

 

No we did not swap the PCM nor did we swap the transmission we only swap the actual engine itself it was running and has been running. It won't start run now. We were thinking that there was also a security problem also. We have some the PCM relearn procedure as well as reset the security . But acts like the security has me locked out of the car starting. Why would I need to change the tranny and PCM???