2H9388 HOSE Caterpillar parts HOSE
Alternative (cross code) number:
Weight: 145 pounds 65 kg.
Illustration 1 g01267205
Parking Brake Switch CircuitThe parking brake switch has two inputs to the ECM. The two inputs are normally open and normally closed. During normal operation, one of the inputs is open. The other input is grounded. When a circuit is measured with a voltmeter, an open circuit will measure approximately 13 DCV to ground and a closed circuit will measure approximately 0 DCV to ground. An FMI 04 diagnostic code is recorded when both of the inputs are grounded.The possible causes of this diagnostic code are listed below:
The "normally open" signal circuit (wire A314-OR) is shorted to ground.
The "normally closed" signal circuit (wire F780-PK) is shorted to ground.
The parking brake switch has failed.
The ECM has failed. This is unlikely. System Response:The diagnostic indicator will flash. The park brake will be engaged.Test Step 1. CHECK THE SWITCH
Check for continuity between contact 1 and contact 2 of the switch.
Press the switch and then release the switch while checking for continuity.
Check for continuity between contact 2 and contact 3 of the switch.
Press the switch and then release the switch while checking for continuity.Expected Result:With the switch released, the resistance between contact 1 and contact 2 is less than 5 ohms. With the switch released, the resistance between contact 2 and contact 3 is greater than 5000 ohms. With the switch pressed, the resistance between contact 1 and contact 2 is greater than 5000 ohms. With the switch pressed, the resistance between contact 2 and contact 3 is less than 5 ohms.Results:
OK - The continuity check agrees with the preceding values. Proceed to Test Step 2.
NOT OK - The continuity check does not agree with the preceding values. The switch has failed.Repair: The parking brake switch has failed. Replace the switch. Verify that the new switch corrects the diagnostic code.STOPTest Step 2. CHECK THE SIGNAL CIRCUITS FOR A SHORT TO GROUND
Disconnect the negative battery cable and turn the key start switch to the OFF position.
Disconnect the machine harness connectors from the ECM. Remove the wire from contact 2 200-BK at the switch.
Measure the resistance between contact J2-54 (wire A314-OR) and frame ground.
Measure the resistance between contact J2-53 (wire F780-PK) and frame ground.Expected Result:The resistances should be greater than 5000 ohms.Results:
OK - The resistances are greater than 5000 ohms.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace"STOP
NOT OK - The resistance is less than 5000 ohms on one of the readings.Repair: The circuit with the low resistance is shorted in the machine harness. Repair the machine harness or replace the machine harness.STOP