VALVE GP-BACK PRESSURE 3506977 - Caterpillar

Illustration 1 g02477320
Connections of the Low Current/Machine Power Distribution Relay
This diagnostic code is associated with the Low Current/Machine Power Distribution Relay. This relay is powered by an "ON/OFF" driver circuit. The FMI 03 diagnostic code is activated when the Relay Driver Module detects an above normal voltage of the relay circuit. This diagnostic code is activated on the Machine ECM via CAN Datalink.The following conditions could cause this diagnostic code to be activated:
The relay has failed.
The relay circuit is shorted to a power source.
The Relay Driver Module has failed. This condition is unlikely.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. Test Step 1. CHECK THE ENERGIZE CIRCUIT OF THE RELAY FOR A SHORT
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connector from the relay. Disconnect the machine harness connector J1 from the Relay Driver Module.
At the machine harness connectors for the Relay Driver Module, measure the resistance between contact J1-13 (wire C903-BU(Blue)) and each of the other circuits that are used in the J1 connector for the Relay Driver Module. Expected Result:Each resistance measurement is greater than 5000 ohms. Results:
OK - Each resistance measurement is greater than 5000 ohms. The resistance measurements do not indicate a short to another circuit in the machine harness. Proceed to Test Step 2.
NOT OK - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness. Repair: The short is between wire C903-BU(Blue) and the circuit that measured a low resistance measurement.For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE OPERATION OF THE RELAY DRIVER MODULEThe disconnect switch and the key start switch remain in the OFF position. The machine harness connectors for the relay and the Relay Driver Module remain disconnected.
At the machine harness connector J1 for the Relay Driver Module, use a 151-6320 Removal Tool to remove the relay wire C903-BU(Blue) and the socket at contact J1-13 from the harness connector.
Reconnect the machine harness J1 connector to the Relay Driver Module.
Turn the disconnect switch and the key start switch to the ON position.
Observe the status of the active CID 3470 FMI 03 diagnostic code. Expected Result:The CID 3470 FMI 03 diagnostic code is no longer active. A CID 3470 FMI 05 diagnostic code is now active.Results:
OK