VALVE GP-PUMP CONTROL 2537766 - Caterpillar

Illustration 2 g02481297
Steering and Transmission Control (Left Steering Joystick)
(1) Connector P-C4
(2) Connector P-C3
(3) Connectors P-C1, P-C2, and P-C5 The CID 2866 diagnostic code is associated with the Steering Control Force Feedback Motor Torque Sensor circuit. The FMI 04 indicates that the ECM has detected that the duty cycle (voltage) of the Steering Control Force Feedback Motor Torque Sensor circuit is below the low voltage threshold.The possible conditions that could cause the Implement ECM to activate this CID 2866 FMI 04 diagnostic code are listed:
The feedback motor circuit is shorted to a ground source.
There is an internal short to ground in the Steering and Transmission Control (Left Steering Joystick) base.
The ECM has failed or the operating software is not the latest version. ECM failure is the least likely cause. Operational Information:During machine operation, the Implement ECM sends a PWM command signal that ranges between 10 percent and 90 percent to the electronics in the Steering and Transmission Control (Left Steering Joystick) base. The internal electronics in the base of the joystick interpret the duty cycle of the command circuit and supply a corresponding amount of current to the torque feedback motor.The internal electronics in the base of the joystick also supply a PWM torque feedback signal to the Implement ECM. The acceptable duty cycle range of the feedback circuit is also 10 percent to 90 percent. During normal operation, the PWM duty cycle of the feedback circuit is expected to be close to the duty cycle of the command circuit. The ECM will use the Force Feedback Motor Torque Sensor duty cycle signal to verify that the correct amount of current is being supplied to the torque motor.During normal operation when no diagnostic codes for the steering joystick are active and the joystick is stationary, the PWM duty cycles of the torque command signal and the torque sensor circuit will be approximately 50 percent duty cycle, however, the torque sensor feedback duty cycle can differ from the command circuit duty cycle by 25 percent. If the signals differ by more than 25 percent, the ECM will activate a CID 2866 FMI 14 diagnostic code.The PWM torque command signal from the ECM and the PWM torque sensor feedback signal to the ECM are difficult to measure. When a torque motor diagnostic code or a position sensor diagnostic code is active, the torque motor is disabled and the duty cycles cannot be measured. To measure the signals during normal operation, insert spoon type probes spoon into the appropriate circuit and the ground circuit. When the primary steering is enabled, the duty cycles of both circuits should be in the 10 percent to 90 percent range .Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections or contamination in a connector can often be the cause of a problem in an electrical circuit. Ensure that the circuit connections are clean, dry, and in good condition. If a problem with a connection is found, correct the problem and