WHEEL-SET 4652107 - Caterpillar

Illustration 1 g01376931
Connections of the parking brake switchThe 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 10 DCV to ground and a closed circuit will measure approximately 0 DCV to ground. The diagnostic code is recorded when the status of both of the inputs are open.The possible causes of this diagnostic code are listed below:
The return circuit (wire 202-BK) is open.
Switch contact "3" (wire A315-WH) is permanently open.
Switch contact "1" (wire A314-OR) is permanently open.
The switch has failed.
The ECM has failed. This is unlikely. Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all of the connections in the circuit are clean and secure. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0070 FMI 03 is active before performing this procedure.
Table 1
Status of the Switch    
MODE    Switch Position    J1-34
wire A315-WH Circuit    J1-33
wire A314-OR Circuit    
Brake OFF     Up     Open     Closed    
Brake ON     Down     Closed     Open    System Response:A level 2 warning will be generated. The ECM retains the last known good state until the parking brake switch is required. The machine is locked out until the diagnostic code is cleared.Test Step 1. CHECK THE GROUND CIRCUIT FOR AN OPEN
Turn the disconnect switch and the keyswitch to the OFF position.
Disconnect the switch from the machine harness.
Measure the resistance between frame ground and contact 2 (wire 202-BK) at the connector for the switch.Expected Result:The resistance should be less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 2.
NOT OK - The resistance is greater than 5 ohms.Repair: The return circuit (wire 202-BK) is open in the machine harness. Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE SWITCH
Check for continuity between contact 1 and contact 2 of the switch.
Press the switch. Release the switch and check for continuity.
Check for continuity between contact 2 and contact 3 of the switch.
Press the switch. Release the switch and check for continuity.Expected Result:The continuity check agrees with Table 1.Results:
OK - The continuity check agrees. Proceed to Test Step 3.
NOT OK - The continuity check does not agree. The switch has failed.Repair: Replace the switch. Verify that the new switch corrects the diagnostic code.STOPTest Step 3. CHECK THE SIGNAL CIRCUITS FOR AN OPEN
Reconnect the switch to the machine harness.
Disconnect the J1 and J2 machine harness connectors from the