I finished my auto to T56 swap a few months ago in my 91 Z28 and have yet to wire up the VSS converter. When I started the car the fan came on immediately and the Check Engine light came on. They both run solid from turn of key and stay on. Was told its in limp mode as I couldn't connect the ALDL to pull codes. Was told to change the ECM but no change. Was wondering if the VSS not being connected can cause this? How likely is it that my PROM is bad? Can anyone point me in a direction of how to start?

thanks
Kris