VALVE GP-SELECTOR & PRESS CONT 3188531 - Caterpillar

operator complaint, proceed to Test Step 2.
Active code - Proceed to Test Step 3.Test Step 2. Check the Integrity of the Connections at the Connectors
Turn the keyswitch to the ON position. Do not start the engine.
Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter.
Check for an intermittent problem at the connector for the suspect sensor:Note: Do not disconnect any harness connectors in order to perform this procedure.
Carefully install the spoons (multimeter probes) into the terminal locations for the +5 volt sensor supply and the sensor return at the connector for the suspect sensor.
While you observe the voltage reading on the multimeter, wiggle the wires and pull on the wires at the connector for the suspect sensor.The voltage reading will not vary more than 0.5 volts for a solid electrical connection.
Remove the spoons (multimeter probes) from the connector.
Check for an intermittent problem at the ECM connector:Note: Do not disconnect any harness connectors in order to perform this procedure.
Carefully install the spoons (multimeter probes) into the terminal locations for the +5 volt sensor supply and the sensor return at the P2 ECM connector.
While you observe the voltage reading on the multimeter, wiggle the wires and pull on the wires for the +5 volt sensor supply and the sensor return at the ECM connector.The voltage reading will not vary more than 0.5 volts for a solid electrical connection.
Remove the spoons (multimeter probes) from the connector.
Turn the keyswitch to the OFF position.Expected Result:The voltage reading did not vary more than 0.5 volts during either test.Results:
OK - The voltage reading did not vary more than 0.5 volts.Repair: The connections are OK at the connectors. There does not appear to be an intermittent problem in the circuit at this time. Return the engine to service.STOP
Not OK - The voltage reading varied more than 0.5 volts during the test.Repair: Disconnect the suspect connector and inspect the connector and the terminals for moisture, damage, and corrosion. Repair the connectors and/or the terminals. Return the engine to service.STOPTest Step 3. Check the Supply Voltage at the Sensor ConnectorTurn the keyswitch to the ON position. Do not start the engine.Measure the voltage between terminal A (+5 V supply) and terminal B (sensor return) at the harness connector for the sensor that relates to the code.Expected Result:The voltage is between 4.5 VDC and 5.5 VDC.Results:
OK - The voltage is between 4.5 VDC and 5.5 VDC. The supply voltage is at the sensor connector. Record the voltage measurement. If you are troubleshooting a -3 diagnostic code, proceed to Test Step 4. If you are troubleshooting a -4 diagnostic code, proceed to Test Step 7.
Not OK - The voltage is less than 4.5 VDC or the voltage is greater than 5.5 VDC.Repair: The voltage of the sensor supply is incorrect. Refer to Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test".STOPTest Step 4. Check for Battery Voltage on the Signal WireMeasure the voltage between the signal terminal and the return