driving. you say its regulated with varying frequency. Lets use simplified values and say you got a signal of 1000Hz and a Duty Cycle of 50%. Voltage is 10 volts at the feed side of whatever you are pulsing. The 50%DC means the circuit is grounded (or actually, FEED in case of said solenoid) for 50% of the time and open for the other half. If you put a regular voltmeter to this circuit it will average what it reads and give you a 5 volt readout. Now lets say you change it to 5000Hz and keep the 50% DC and put the VOM at it, what do you read? Still 5V. Its still the average voltage. However if you keep the 1000hz and vary the dutycycle to say 20% you may read 2 volts with a VOM. Or maybe 8 volts at 80% DC. Of course things like inductance and shit plays a role with solenoids of all sorts. If you look in the FSM at page ST-40 you will see a reference to different voltages at different speeds (diagnostics page). You can also see a reference to APMERAGE some other place in the manual.
In my own car i deleted the HICAS system. To keep the HICAS light off i unplugged one of the connectors on the HICAS module. This results in a fixed setting as you describe that is a little too heavy at low speed for my likings. Now i also run an aftermarket ECU where i can set up an output however i want. I measured the frequency the Hicas module pulses the solenoid with which was 6000Hz. Hooked the solenoid directly to my ECU. Then i hooked up an amperemeter to the circuit and varied the dutycycle to achieve the different ampere readings stated in the FSM. Plugged the different DC numbers found into a 2D table in the ECU vs different vehicle speeds and Bobs your uncle. Works as nothing was ever wrong in the system. Measured from 48% DC at standstill to 13% at its heaviest (fastest vehicle speed)
