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ECM keeps telling PTO to shut off

moocowman

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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?
 

moocowman

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In case anyone is interested, the problem is solved. Or at least, worked around. I don't know what the problem was really, but I changed the setting to disable the driver's accelerator pedal while PTO is on and the PTO no longer shuts off unexpectedly. One would think this means the ECM is shutting off the PTO because it thinks someone is stepping on the accelerator. But, I also noticed the problem would resolve when I decreased the PTO engine RPM 2 setting to 1250 or lower instead of the 1300 it was set at. I don't know why 1300 is the magic number.

If anyone could explain why this happens, let me know.
 

moocowman

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Ok, this isn't over. It worked for half the day then qent back to shutting off again. I changed Preset PTO Set RPM to 1200 (instead of 1300) and it's staying on now, but this is just a Band-Aid and probably won't work forever. If anyone with intimate knowledge of this issue can help, please chime in.
 
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