Hi everyone, Here is an update regarding the CAT 320B governor motor test. I performed a bench test under no-load conditions (mesure à vide) in our workshop to record the exact electrical measurements, motor response, and travel behavior. Here are the key measurements from the test: 1. Supply Voltage: Stable at 23.3V DC (bench supply under no-load conditions). 2. Feedback Signal: The internal potentiometer signal smooths linearly between 3.89V and 3.91V without any voltage drops or spikes. 3. Mechanical Movement: Actuator linkage travel operates smoothly with no binding or hesitation. You can check the full workshop bench test video here: https://drive.google.com/file/d/1B_kjVvo...p=drivesdk Could the experts here please take a look at the video and confirm if these values are correct and within factory specifications? Thanks in advance for your help and feedback! Best regards, DOUAHCHIA
The supply voltage looks acceptable, but the feedback potentiometer signal is not normal. Evaluation of Your Bench Test Results 1. Supply Voltage: 23.3 V DC (stable, no-load) This is within the expected range. On the 320B governor actuator, the main power supply (typically pins 1 & 2 – battery positive to ground) should read approximately 18–24 V with the key on. 23.3 V is fine for a bench supply under no-load conditions. 2. Feedback Signal: 3.89 V → 3.91 V (smooth, linear, no drops/spikes) This is not within normal factory behavior. The internal potentiometer (position feedback sensor) is supposed to produce a clear, usable voltage swing as the actuator travels through its full range. Typical expected feedback range on these units (when measured correctly between the signal pin and ground/reference) is roughly 0.6 V to 11.4 V or a substantial portion of the reference voltage (commonly a 4.5–5.5 V supply to the pot itself). A total change of only 0.02 V across the travel means the potentiometer is essentially not tracking position. Possible causes: • Failed / worn potentiometer (very common failure mode on these actuators) • Mechanical slip or disconnection inside the actuator between the motor/gear and the pot shaft • Incorrect measurement points or the unit only being moved a very small distance during the test 3. Mechanical Movement: Smooth, no binding Good. The motor and linkage can move freely under no-load. This rules out severe mechanical seizure but does not guarantee the feedback sensor is working. Conclusion The actuator is not electrically healthy according to the feedback readings. Smooth mechanical travel + almost flat potentiometer signal is a classic signature of a bad feedback pot (the exact condition that produces codes such as 2301 “feedback signal not stable” or 2302 “feedback signal deviates/biased” on the 320B).
Thanks a lot for the explanation! Your conclusion about the feedback pot and codes 2301/2302 makes total sense given the readings. I will check the potentiometer and wiring accordingly. Highly appreciate your help
Glad it helped, hopefully you’ll be back up and running!