2001 Eclipse no start, code 1610

Hello all,
I bought my son a 2001 Eclipse GS 4cyl. It would not start. I found that the Ecm was not working. Check engine light would not come on with ignition and my hand held could not communicate. I ordered and replaced the Ecm and now the light works and I can communicate. The vehicle will not start. I get a code p1610. Does anyone know if this car has a pass key? Does it need to be reprogrammed? I appreciate any info anyone can offer.
Briantman

The car does have an immobilizer with the resistance keys.

To anyone interested, Yes it does have a chip in the key. Not all do. The code 1610 is a direct code for loss of key immobilizer. This has to be programmed by a dealership. That sucks cause it is not cheap.

Have a nice day!
Briantman