Engine System, Diesel 242Service Manual – CS7000
Cannot Achieve Either Run or Maximum Engine Speed Settings (Run 2200 RPM,
Maximum Power 2400 RPM).
The approach to diagnosing an engine RPM control problem is to check the inputs to the governor controller
and check the output to the actuator. If the inputs are good and the output is bad, the conclusion is that the
controller is the problem. If the output control is okay but the RPM doesn’t change, then the actuator is the
likely problem. However, don’t forget that insufcient fuel supply or a restricted exhaust could appear like
an RPM control problem if the engine cannot run well enough to achieve a higher RPM.
Possible Causes:
• Actuator
• APECS 3000 Governor Controller
• Wiring
• Main Machine Controller
Diagnostic steps:
1. Check the power and ground supplies to the controller.
a. Is there sufcient power and ground?
◦ If so, go on to check the speed request inputs.
◦ If not, repair.
2. Check the speed request inputs
a. With the engine running press the engine speed button and check for 12v to the throttle 1 and
throttle 2 wires at the governor controller.
b. Is 12v present on either of the throttle wires with the engine running at idle speed?
◦ If so, go on to check the actuator output
◦ If not, check the wiring between the main machine controller and the governor controller.
3. Check the actuator output.
a. Does it change with the speed request?
◦ If so, the actuator is the likely problem.
◦ If not, the controller appears to be the problem.
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