PISTON 4431731 - Caterpillar

Illustration 1 g01008903
Troubleshooting Chart
Illustration 2 g00735873
Schematic for the Pressure Sensor (Rod End of the Lift Cylinder)This diagnostic code is recorded when the ECM for the payload system determines that the signal from the pressure sensor for the rod end is outside the allowable range.Note: The lift control lever should be in the FLOAT position. The ride control (if equipped) should be OFF.Note: Ensure that the diagnostic code is still active.Test Step 1. CHECK THE FREQUENCY OF THE PRESSURE SENSOR
Turn the key start switch to the OFF position.
Disconnect the machine harness from the ECM for the payload system.
Install a 8T-0859 Pressure Gauge and the proper Diagnostic Hose on the pressure tap for the sensor. Route the diagnostic hose and the pressure gauge into the cab. Route the diagnostic hose so the hose will clear the lift arms during the test.
Connect a 9U-7330 Digital Multimeter or a 8T-5201 Generator and Counter Signal Group between contact 21 (wire 251-BK) and contact 16 (wire E416-PU) for the ECM.
Turn the key start switch to the ON position.
At the connector for the ECM, measure the frequency of the pressure sensor for the lift arms with zero pressure at the cylinder.
Tilt the work tool to the full BACK position. Lower the lift arms until the pressure on the gauge reads 20700 kPa (3000 psi). When the pressure gauge reads 20700 kPa (3000 psi) observe the frequency displayed on the digital multimeter.Expected Result:The frequency should read approximately 200 20 Hz at a pressure of 0 kPa (0 psi). The frequency should read approximately 800 30 Hz at a pressure of 20700 kPa (3000 psi).Results:
YES - The frequency is approximately 200 20 Hz at a pressure of 0 kPa (0 psi). The frequency is approximately 800 30 Hz at a pressure of 20700 kPa (3000 psi).Repair: It is unlikely that the ECM for the payload system has failed. Perform the previous steps again. If the cause of the problem is not found, replace the ECM. See Testing and Adjusting, "Payload Electronic Control Module - Replace".STOP
NO - The frequency is not approximately 200 20 Hz at a pressure of 0 kPa (0 psi). The frequency is not approximately 800 30 Hz at a pressure of 20700 kPa (3000 psi). The frequency of the pressure sensor is not correct. Proceed to Test Step 2.Test Step 2. CHECK THE +BATTERY VOLTAGE
Turn the key start switch to the OFF position.
The connector for the ECM remains disconnected.
Disconnect the wire harness from the pressure switch.
At the connector for the pressure switch, measure the voltage between A (wire 138-GN) and B (wire 251-BK).Expected Result:The voltage at the pressure sensor is at least 18 volts.Results:
YES - The voltage is greater than 18 volts. The voltage is correct. Proceed to Test Step 3.
NO - The voltage is less than 18 Volts. The voltage is not correct. There may be an open or a short in the wire harness.Repair: Repair the harness or replace the harness.STOPTest Step 3. CHECK FOR AN OPEN IN