TOOL G-WATER 6V7860 - Caterpillar

Illustration 1 g00578692
Schematic of the pressure switch (service brake)This switch has an input to the brake/cooling ECM. The input is normally closed. The input is grounded when the switch is actuated. When a circuit is measured with a voltmeter, an open circuit will measure approximately 5 DCV and a closed circuit will measure approximately 0 DCV. An FMI 04 diagnostic code is recorded when the status of the input is grounded for an extensive period of time.The possible causes of this diagnostic code are listed below:
The signal circuit (wire 706-BR) is shorted to ground.
The switch has failed.
The ECM has failed. This is unlikely. Test Step 1. CHECK THE SWITCH
Be sure that the diagnostic code is active.
Disconnect the machine harness from the switch.Expected Result:The diagnostic code is no longer active.Results:
OK - The diagnostic code is no longer active.Repair: The pressure switch has failed. Replace the pressure switch. Verify that the new switch corrects the diagnostic code. Stop.
NOT OK - The diagnostic code is still active. Proceed to Test Step 2.Test Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND
Disconnect the machine harness connector J1 from the brake/cooling ECM.
Measure the resistance between contact J1-46 (wire 706-BR) and frame ground.Expected Result:The resistances should be greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the diagnostic code is still present, replace the ECM. Refer to Testing And Adjusting, "Electronic Control Module (ECM) - Replace". Stop.
NOT OK - The resistance is less than 5000 ohms.Repair: The circuit is shorted to ground within the machine harness. Repair the machine harness or replace the machine harness. Stop.