Several temperature features are in the logic. Both RE and RH. If below a certain temperature you cannot get OD or LU. This is to promote warmup and prevent fluid starvation to the OD when super cold. The OD is the last guy to get fluid in the lube circuit. It comes from TC output like a 727 but the fluid enters the case like normal - then splits off once inside to lube the OD and the intermediate shaft and trans geartrain.

If TOO hot - above i think 265 F, then OD is defeated, shifts to 3rd, and LU is turned on to reduce converter slippage and resultant heat build up. Once the temp drops, then OD is allowed.

The controls look at neutral safety position, temperature, shaft speed, outside temperature, engine speed, to name a few things.
If neutral safety reports N or P, you lose OD. We watch for engine speed reduction when we turn on LU, if we do not see an engine speed drop in a certain amount of clock time- we set a TC code. Some of the inputs are used to verify plausibility when we get certain bad inputs or no inputs. Not sure what your controls logic is going to include but you may want to incorporate some of these for safety reasons.