How to solve the problem of intermittent low power or reduced power of the 3126B diesel engine and
C-9 diesel engine used in Caterpillar excavators
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1. Cause of failure
(1) The diesel engine operates with reduced load under conditions such as high altitude and clogged air filter.
(2) The throttle switch is not working properly.
(3) The ECM power supply, ground wire or connector is faulty.
(4) The fuel system is faulty. (5) The injection drive pressure is too low.
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2. Troubleshooting
(1) Use ET to check recorded diesel engine load reduction and/or current existing diesel engine load
reduction conditions. If the diesel engine load reduction operation currently exists, then the ET will
display the load reduction operation status signal. At high altitudes, with dirty air filters and other
conditions, the diesel engine will run at reduced load.
(2) Monitor the throttle switch on the ET and check whether the throttle switch is working properly.
Please refer to Section 11 and 15 of this chapter.
(3) Ensure that ECM connectors J1/P1 and J2/P2, injector connector J300/P300, camshaft position
sensor connectors J401/P401 and J402/P402 are installed correctly.
(4) Use electronic maintenance tools to check the fault code 0168-02 (intermittent battery power to the
ECM), check the electrical connector and grounding wire of the ECM, if a fault is suspected, use wires
to bypass it, please refer to Chapter 11 Contents of Section 5.
(5) Monitor the fuel configuration value, rated fuel limit value and FRC fuel limit value through ET.
①If the fuel configuration value is equal to the rated fuel limit value and less than the FRC fuel limit
value, it is said that the electronic components are working normally.
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② If the fuel configuration value
is not equal to the rated fuel limit value and/or is greater than the FRC fuel limit value, then when the
diesel engine is turned off and the ignition key switch is turned to the ON position, the turbocharger
outlet pressure on the electronic maintenance tool screen should be OkPa.
(6) Check the fuel system.
(7) Check the injection drive pressure.
