replaced ECM,now trans.codes,3rd gear start.

Question

Does ECM need to be programmed,out of same vehicle with matching service #on ECM.

Answer 1

Yes it does, the 1999 uses a VCM (vehicle control module) becuse of the transmission code this is a incompatible VCM. the knock sensor module will need to be transfer(if it already has been) and you should have the CKP (crank position sensor) variation relearn performed or you will have P1336 , Here is a diagram of the knock sensor modulehave the VCM reprogrammed