They're both "on" for low gear / 1st. Activating 2nd gear is done by shutting off solenoid 1, but leaving solenoid 2 on.

There are 2 solenoids which yields 4 combinations of on/off, each corresponding to one of the 4 gears. So the pcm just flip flops between those 4 combinations of on + off to get the gear it desires.


If you're looking for hydraulic or wiring diagrams, I'd suggest buying the ATSG service manual for them, lots of good info on that kind of stuff in there.