KIT- 4669529 - Caterpillar

Illustration 1 g02141717
Connections of the parking brake switch
The Parking Brake Switch is a two-pole double-throw switch. One pole is used to provide two switch-to-ground inputs to the power train ECM in order to indicate the status of the switch. The other switch pole is used to energize the Parking Brake Dump Solenoid.During normal operation, one of the inputs is not connected to ground and the other input is connected to ground through the switch contacts. An internal pull-up voltage is present at the ECM switch inputs. When the input is grounded through the switch, the ECM detects the ground signal. When the Parking Brake Switch is moved to the Brake ON position, system voltage will be directed to the Parking Brake Solenoid through Fuse 20. This results in the parking brake being engaged. The ECM will determine that the switch is in the Brake ON position when the input at J1-35 is grounded.The FMI 03 diagnostic code is activated by the ECM when neither of the inputs is showing a ground signal.The possible causes of this diagnostic code are listed:
The switch has failed.
The ground circuit has an open circuit or a bad connection.
There is an open or a bad connection in one or both of the input circuits.
The ECM has failed. An ECM failure is unlikely.
Table 1
Parking brake switch contact states
Switch Position J1-35 wire (419-YL(Yellow)) J1-40 wire (F780-PK(Pink))
Brake ON Closed(1) Open(2)
Brake OFF Open(2) Closed(1)
(1) Closed to ground wire (L740-BR(Brown))
(2) Open to ground wire (L740-BR(Brown))Note: 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 connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these 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.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. Check the operation of the switch
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector from the switch.
Move the switch to the ON position.
Measure the resistance from contact "2" to contact "1". Measure the resistance from contact "2" to contact "3". Compare the measurement to Table 1.
Move the switch to the OFF position.
Measure the resistance from contact "2" to contact "1". Measure the resistance from contact "2" to contact "3". Compare the measurement to Table 1. Expected Result:The resistance measurement in each switch position is correct according to the table at the beginning of this procedure.Results:
YES - The resistance measurements are correct in each switch position according to the table. Proceed to Test Step 2.
NO - The resistance measurements are