HOSE GP 5126139 - Caterpillar

Illustration 2 g03741451
The Illustration details the electrical connections for the "Hoe Left" and "Hoe Right" thumbwheel controlNote: Each thumbwheel includes two position sensors to monitor output. The signals are sent to the Machine ECM and compared to confirm the thumbwheel is operating correctly. Sensor 1 provides the control signal that is sent to the ECM to determine the position of the solenoid spool. The voltage output from Sensor 2 is used to validate the voltage output from Sensor 1. The relationship between the analog signals, when operating correctly, is displayed in Illustration 3.
Illustration 3 g03741513
Dual Analog Signal Relationship Table
The Machine uses the following calculation to validate the signal from Sensor 1:Signal 1 + Signal 2 = Vcc ( VT), where VT is Validation Tolerance. Vcc is provided by the 5 VDC power supply of the Machine ECM.To observe the simultaneous output of the sensors, Cat® "Electronic Technician" (CatET) must be used to monitor the signals from the sensors. Under normal operating conditions, the maximum voltage output of the sensor will not exceed 4.5 VDC. The minimum output of the sensors will not be less than 0.5 VDC, given a 5 VDC supply voltage.Diagnostic Trouble Code Procedure
Note: Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Identify Active DTC Code Associated With Thumbwheel Sensor Circuit    
Code present     FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 5.    
Begin Process For FMI 3 Troubleshooting HERE    
2. Check The Supply Voltage for the Sensor
A. Turn key start switch and battery disconnect switch ON.
B. Disconnect the machine harness from the joystick.
C. Refer to the schematic to determine the wire identification for the voltage source of the suspected faulty sensor. For the "Loader Joystick" thumbwheel circuit refer to Illustration 1. For the Left and Right Joystick thumbwheel control refer to 2.
D. Measure voltage between supply and return contacts at the machine harness connector for the joystick.    
Voltage is 5 VDC 0.3     OK - The voltage reading is correct for the suspected faulty thumbwheel circuit.
Proceed to Test Step 3.
STOP
NOT OK - The voltage is NOT correct for the circuit.
Repair - Follow the procedure described in Troubleshooting, "Sensor Supply - Test" found in this manual to repair the voltage supply circuit.    
3. Check For An Open In The Thumbwheel Sensor Circuit
A. The joystick remains disconnected from the machine harness.
B. Turn the key start switch and battery disconnect switch OFF and wait for the DEF warning lamp to go out before proceeding.
C. At the harness connector for the joystick, place a jumper wire between the signal contact