HANDRAIL GP 4262523 - Caterpillar

FMI-4 Failure Mode
Replace the Rotary Position Sensor if there is no duty cycle on pin C when both of the following conditions are present:
The machine key switch is on.
There is a power supply on the Rotary Position Sensor connector pin A (+24V) and pin B is grounded (GND).Refer to Special Instruction, REHS7312, "Instructions for Installing Rotary Position Sensor for Cat® Grade Control on Certain Series E and Series F Excavators" for complete instructions on replacing or reinstalling the Rotary Position Sensors. Refer to System Operation, Testing and Adjusting Manual, UENR1725, "Cat® Grade Control Depth & Slope for E-Series and F-Series Excavators" for instructions on how to calibrate the replaced sensor and the Cat® Grade Control system.
Use the following steps if there is a power supply present on the machine harness and a duty cycle present throughout the range of motion of the sensor:
Turn the key switch off.
Secure the machine and follow all safety steps prior to servicing the machine.
Perform a resistance check of the signal wire to the machine ECM. Refer to Table 3.
If all troubleshooting steps have been completed and checked, replace the Cat® Grade Control ECM.Note: Failure of the Machine Implement ECM is highly unlikely.
Reflash the ECM and calibrate the Cat® Grade Control system.Note: The latest flash software file for the Machine Implement ECM can be obtained from SIS web (http://sisweb.cat.com).
Retest the Cat® Grade Control system. Ensure that there are no codes present and the Cat® Grade Control system is functioning properly.
Illustration 8 g06052495
Pin positions on sensor
Table 3
Excavator Boom and Stick Rotary Position Sensor Contact Descriptions
E Models: 312, 314, 318, 320, 323, 324, 329, and 336
F Models: 312, 318, 320, 323, 326, 330, 336, 349, and 352
Boom Sensor Connector Pin Function Implement ECM Connector/Pin
A +24 V Sensor Power Supply -
B Sensor Ground (GND) -
C PWM Signal F-C63/50
Stick Sensor Connector Pin Function Implement ECM Connector/Pin
A +24 V Sensor Power Supply -
B Sensor Ground (GND) -
C Sensor Output PWM Signal F-C63/47
Models: 336E H, 336F XE, 374F, and 390F
Boom Sensor Connector Pin Function Cat® Grade Control (CGC) ECM Connector/Pin
A +24 V Sensor Power Supply -
B Sensor Ground (GND) -
C Sensor Output PWM Signal GP-C23/68
Stick Sensor Connector Pin Function Cat® Grade Control (CGC) ECM Connector/Pin
A +24 V Sensor Power Supply -
B Sensor Ground (GND) -
C Sensor Output PWM Signal GP-C2/23 Replacing or Reinstalling the Boom or Stick Rotary Position Sensors
Illustration 9 g06052519
Boom Rotary Position Sensor
(4) Wiring
(5) Flat side of shaft
Illustration 10 g06052529
Stick Rotary Position Sensor
(4) Wiring
(5) Flat side of shaftEnsure proper installation when the Rotary Position Sensors are replaced or reinstalled. Proper installation is critical to the Cat ® Grade Control system and the accuracy of the system.The sensors can be visually verified. Before the linkage arm is connected, ensure that the flat spot on the rotor shaft is facing away from the harness location. Ensure that the three bolt pattern is in the housing of the sensors. Refer to Illustration 9 and Illustration 10.Note: If the Boom or Stick Rotary Position Sensors are replaced or reinstalled, a calibration of that sensor is