87 Dakota stuck in open loop?

1. engine temperature sensor - checks out within range of factory specs. I also checked it by installing in its place a resistor of 720 ohms to simulate a warmed up engine. Closed loop operation did not take place.
2. wiring of engine temperature sensor to computer - no shorts or opens
3. O2 sensor - checks out within range of factory specs

I am in the procees of sifting through Alldata's info on this vehicle to see what sensors trigger closed loop operation and check them out one by one. There are not many on this vehicle.

I am beginning to suspect that the computer may be unable to function in closed loop mode and is limping by in open loop. Is this possible?

Thanks for any and all help.

Jack California