YOKE AS 4E5230 - Caterpillar

Illustration 1 g03366580
Starter Motor Relay connections
This diagnostic code is associated with the starter motor relay. The FMI 03 diagnostic code means the ECM has determined that voltage is present in the relay circuit when the output driver is OFF.The possible causes of the diagnostic code are listed below:
The relay has failed.
The power circuit of the relay is shorted to another voltage source.
The ECM has failed. This situation 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 cause other diagnostic codes to activate. Ignore these created diagnostic codes and clear these diagnostic codes when the original problem has been corrected.Test Step 1. CHECK THE RELAY
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector from the relay for the starter motor.
At the connector for the relay, measure the resistance of the coil between contact 1 and contact 2. Expected Result:The resistance of the relay coil should measure approximately 27.5 3 ohms at 20 °C (68.0 °F). Results:
OK - The resistance measurement of the relay coil is within the acceptable range. Proceed to Test Step 2.
NOT OK - The resistance measurement of the relay coil is NOT within the acceptable range.Repair: The relay coil is not correct. Replace the relay for the starter motor. After the relay has been replaced, verify that the new relay corrected the problem before operating the machine.STOPTest Step 2. CHECK THE ENERGIZE CIRCUIT OF THE RELAY FOR A SHORTThe key start switch and the disconnect switch remain in the OFF position. The machine harness connector remains disconnected from the relay.
Disconnect the harness connectors J1 and J2 from the ECM.
At the machine harness connector for the ECM, measure the resistance from contact J2-7 (wire 306-GN(Green)) to all of the contacts that are used in the machine harness connectors for the ECM. Expected Result:Each resistance measurement is greater than 5000 ohms. Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness. The short is between wire 306-GN(Green) and the circuit that has a low resistance measurement. Repair: Refer to the complete Electrical System Schematic of the machine. Examine all of the connectors in circuits for points in the machine harness where the circuits could be shorted. 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 3.