FILM-IDENTIFICATION 2727076 - Caterpillar

Illustration 1 g01434030
Parking Brake Dump Solenoid connectionsThis diagnostic code is associated with the Parking Brake Dump Solenoid. The solenoid is connected to an ON/OFF output of the Machine ECM. The FMI 03 means that the ECM has detected that voltage is present in the circuit when no voltage should be present.When the Parking Brake Switch depressed, system voltage will be directed to the Parking Brake Solenoid through Fuse 28 and through the circuit diode. This results in the parking brake being engaged. The ECM monitors the circuit and the ECM can also energize the Parking Brake Solenoid under certain machine conditions.Conditions that could causes this diagnostic code to be activated are:
The Parking Brake Switch has failed.
The energize circuit of the solenoid is shorted to another voltage source.
The ECM has failed. This is unlikely.Before performing this procedure, Verify that there is not a CID 070 active for the parking brake switch. If a diagnostic code is active for the switch, refer to the troubleshooting procedure for the active diagnostic code and resolve the problem before performing this procedure.This procedure should not require entry into any enclosures that contain hazardous voltage components and should not require any hazardous voltage connections to be disconnected.When an area that contains hazardous voltage components must be entered for a service procedure, the "Safe Shutdown Procedure for Electric Drive Tractors" procedure must be performed before any enclosures that contain hazardous voltage components are opened or before any hazardous voltage connectors are disconnected. Refer to the Troubleshooting, "Electrical Maintenance Guidelines" section of this manual. Perform the "Safe Shutdown Procedure for Electric Drive Tractors" procedure before any of the hazardous voltage areas are opened or before hazardous voltage connectors are disconnected.Note: The resistance of a good Parking Brake Solenoid coil is approximately 42 ohms at approximately 25 °C (77 °F). Resistance will increase as the temperatures increase.Note: The following test procedure may cause other diagnostic codes to be activated. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected. Ensure that the CID 0681 FMI 03 diagnostic code is active before performing this procedure.Test Step 1. CHECK THE SOLENOID
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the solenoid from the machine harness.
At the solenoid connector, use a multimeter to check the resistance of the solenoid coil between contact 1 and contact 2.Expected Result:The resistance of a new Parking Brake Dump Solenoid coil is approximately 42.0 ohms at approximately 25 °C (77 °F). Resistance will increase as the temperatures increase.The main concern here is that the coil winding is not shorted which would result in a very low resistance measurement.Results:
OK - The resistance of the solenoid coil is approximately 42.0 ohms. The solenoid appears to be OK. Proceed to Test Step 2.
NOT OK - The resistance of the solenoid coil is much less than 42.0 ohms. The coil winding appears to be shorted. The solenoid is faulty.Repair: The solenoid coil is shorted. Replace the Parking Brake Dump Solenoid.