TRACK GP 3985240 - Caterpillar

Illustration 1 g01183883
Schematic for the pressure sensor (Head end for the lift cylinder)
This diagnostic code is recorded when the electronic control module (ECM) for the Payload Control System (PCS) determines that the signal from the pressure sensor for the head end is incorrect.The possible causes of this diagnostic code are listed:
The signal circuit is open.
The +battery circuit from the electrical system to the sensor is open.
The signal circuit is shorted to the +battery.
The signal circuit is shorted to ground.Test Step 1. CHECK THE VOLTAGE FROM THE SIGNAL CIRCUIT
Turn the key start switch to the OFF position.
Disconnect the machine harness from the pressure sensor.
Turn the key start switch to the ON position.
At the harness connector for the pressure sensor, measure the voltage between contact B (wire 251-BK(Black)) and contact C (wire C529-GY(Grey)). Note: Use a calibrated digital multimeter.Expected Result:The voltage is 5 .5 VDC.Results:
YES - The voltage is 5 .5 VDC. The voltage is correct. Proceed to Test Step 5.
NO - The voltage is not 5 .5 VDC. The voltage is not correct. Proceed to Test Step 2.Test Step 2. CHECK THE +BATTERY VOLTAGE
Ensure that the key start switch is in the ON position.
At the harness connector for the sensor, measure the voltage between contact A (wire 138-GN(Green)) and contact B (wire 251-BK(Black)). Expected Result:The voltage is between 9 VDC and 32 VDC.Results:
YES - The voltage is between 9 VDC and 32 VDC. The voltage measurement is correct. Proceed to Test Step 3.
NO - The voltage is less than 9 VDC. The voltage is not correct. There may be an open or a short in the machine harness.Repair: Repair the harness or replace the harness.STOPTest Step 3. CHECK FOR AN OPEN IN THE SIGNAL CIRCUIT
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the connector for the ECM.
The machine harness from the pressure sensor remains disconnected.
Measure the resistance between contact C (wire C529-GY(Grey)) at the connector for the pressure sensor and contact J2-32 at the connector for the ECM. Expected Result:The resistance should measure less than 5 Ohms.Results:
YES - The resistance is less than 5 Ohms. The resistance is correct. Proceed to Test Step 4.
NO - The resistance is greater than 5 Ohms. The resistance is not correct.Repair: Repair the harness or replace the harness.STOPTest Step 4. CHECK FOR A SHORT IN THE SIGNAL CIRCUIT
The disconnect switch and the key start switch remains in the OFF position.
At the connector for the ECM, measure the resistance between contact J2-32 (wire C529-GY(Grey)) and the other contacts that are in the connector for the ECM. Expected Result:Each measurement should be greater than 5000 Ohms.Results:
YES - The resistance measurement is greater than 5000 Ohms. The resistance is correct. Proceed to Test Step 5.
NO - The resistance measurement is less than 5000 Ohms. The resistance measurement is not correct. There is probably a short in the signal circuit for the machine harness.Repair: Repair the harness or replace the harness.STOPTest Step 5. CHECK THE FREQUENCY OF THE PRESSURE