VALVE GP-RELIEF 2028812 - Caterpillar

Illustration 1 g01377699
Schematic of the left front drive motor speed sensorThis diagnostic code is recorded when there is no signal from either input of the left speed sensor in the manual mode.The following conditions could cause this diagnostic code to be activated:
The power wire (T800-OR) for the sensor is open.
The return wire (J767-GY) for the sensor is open.
The return wire (J767-GY) for the sensor is shorted to the + battery circuit.
The signal wire (J717-BU) is open.
The signal wire (J717-BU) is shorted to the + battery circuit.
The signal wire (J717-BU) is shorted to ground.
The sensor is faulty.
The left drive pump has failed.
The left charge pump has failed.
The charge pressure is low.
The input gears of the pump have failed or the shaft has failed.
The ECM is faulty. This is unlikely.Test Step 1. VISUALLY VERIFY THAT THE FRONT WHEELS ARE SPINNING
Select forward direction. Select maximum "Creep" speed.
Engage "AWD Creep mode" and lower the blade in order to lift the front wheels off the ground.
Verify that the green AWD indicator is illuminated.
Select reverse direction. Select maximum "Creep" speed.
Engage "AWD Creep mode" and lower the blade in order to lift the front wheels off the ground.
Verify that the green AWD indicator is illuminated.Expected Result:Both front wheels turn in both forward and reverse directions in "Creep mode". The green AWD indicator should illuminate.Results:
Green AWD Indicator does not activate. - Check ET for other active AWD diagnostics or events. Clear the diagnostic codes that are active. Proceed to Test Step 1.
Both front wheels spin as expected. - Proceed to Test Step 2.
One or both wheels do not spin when commanded in one or both directions. - Proceed to Test Step 3.Test Step 2. CHECK THE SPEED SENSOR
Perform the Testing and Adjusting, "Speed Sensor - Test" procedure.Expected Result:Speed sensors should read correct speed and direction.Results:
OK - Speed and direction are correct. There is an intermittent open circuit or a short circuit in the harness of the speed sensor. Repair: Locate the intermittent open circuit and the short circuit. Repair the harness of the speed sensor.STOP
NOT OK - Speed and direction are incorrect. Repair: For information on diagnostic procedures, refer to the Troubleshooting, "MID 075 - CID 2319 - FMI 02" Story in this manual. Repair the harness of the speed sensor.STOPTest Step 3. CHECK THE CLUTCH PRESSURE
Perform the Testing and Adjusting, "Solenoid Valve (Control Manifold) - Test" procedure.Expected Result:Clutch pressure should be within the tolerance that is specified in the test procedure.Results:
OK - Readings of clutch pressure are within the