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PTO status turns off, can't figure out what's causing it


New Recruit
Fleet Manager
2014 Hino 338 with PTO and remote throttle switch installed (non-OEM). PTO turns keeps turning off. I monitored the PTO switch and remote throttle switch (scanner sees them as PTO switch 1 and PTO switch 2) and both switches show as "ON" when the problem occurs. So, there's no problem with the switches or wiring for the switches. PTO Status changes to "OFF" and PTO Cut Relay changes to "ON". I know something is telling the ECM to turn off the PTO, but don't know what. Brake Switch, Stop Light Switch, Accelerator Pedal Sensors 1 and 2, Target vs. Commanded Fuel Rail Pressure all look ok. What else might be causing the ECM to turn off the PTO or how else might I diagnose this?