This seems to be convenient timing. I have been speaking with tech support at Parker Services. They are dealers for the APECS 4500. They have been incredibly helpful, but we are still trying to figure out the best path forward. I borrowed an oscilloscope from work and measured the signal coming from the magnetic pickup (MPU) on the PTO and the signal going to the actuator under the hood.
Here is what I found. When the generator is running at 60Hz with no load:
The MPU is putting out a signal of about 475Hz sine wave with the signal oscillation from +12V to -12V.
The actuator under the hood is a DYNA 8000 and needs a pulse width modulation signal (PWM). This signal for me was a 373 to 375 Hz square wave, duty cycle of 61%, and a voltage from -1V to +8V. The duty cycle changes the actuator position. so this could be a little different based on the linkage setup for each truck.
So far we have determined that the 475Hz signal from the MPU is a low frequency for a typical engine governing signal. We are looking at other controllers that may be more simple and require less programming than the APECS 4500, but the 475 Hz frequency is not common. typical ranges seem to be from 500 to 11,000Hz based on manuals I have read. Below are pictures of the signals. The DMM on top is the Hz and voltage coming from the generator.