apm? air pressure? if so as far as I know the air pressure commands are for testing only
I looked again. it seems to be a hybrid thing. under powertrain, accessory power module, special functions. I get apm setpoint control.
while in there I did see the cooling fan test for relay 1, 2 and 3. these trucks use a resistor pack on each fan to make 3 speeds. 1 sounded like low speed and both fans came on. 2 sounded litter faster and both came on. 3 was crazy loud but only the passenger side came on. guess I gotta dive into that and see with summer coming. I remember looking at the wiring diagram once and getting a slight headache lol. guess I'm diving back in.
I'm not even sure it should run both for just relay 3 turned on. I turned the ac on max with the windows down but it's not hot enough, high 80s at best. could only get high side pressure up to 198 and relay 2 commanded on. 3 never was.