ENGINE AR-PRIMARY 3050477 - Caterpillar

Illustration 1 g01322415
Connections of "Differential Lock" relay
This diagnostic code is associated with the "differential lock" relay. The "differential lock relay" is controlled by the ECM through an "ON/OFF" output driver. The FMI 03 means that the ECM has determined that the voltage is present in the relay circuit when the output driver is OFF.The conditions that could cause this diagnostic code to activate are listed below:
The relay has failed.
The energize circuit of the relay is shorted to another voltage source.
The ECM has failed. This 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 be activated. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.Test Step 1. CHECK THE RELAY
Turn the key start switch and the disconnect switch to the ON position.
Observe the status of the active CID 2304 FMI 03 diagnostic code and disconnect the "differential lock relay" from the machine harness.
At the relay, measure the resistance of the coil between contact 85 and contact 86. Measure the resistance between power contact 30 and all of the other relay contacts. Expected Result:When the relay is disconnected from the harness, the status of the active CID 2304 FMI 03 diagnostic code does not change.The resistance of the relay coil is in the range of 288 to 396 ohms at 25 °C (77 °F).The resistance measurement between power contact 30 and contact 87a is less than 5 ohms. The measurement of the resistance between the power contact 30 and all the other contacts of the relay is greater then 5000 ohms.Results:
YES - All of the checks for the relay are correct. The relay is not the cause of the problem. The CID 2304 FMI 03 diagnostic code is still active. Proceed to Test Step 2.
NO - The active CID 2304 FMI 03 diagnostic code became inactive when the relay was disconnected. The resistance checks are not correct, according to the expected results that are listed above. The relay has failed.Repair: Verify that the relay has failed by substituting a known good relay that is the same part number for the faulty relay. The relay for the backlight can be substituted. Replace the faulty relay.STOPTest Step 2. CHECK THE ENERGIZE CIRCUIT OF THE RELAY FOR A SHORT The relay remains disconnected from the machine harness.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors J1 and J2 from the Transmission/Chassis ECM.
At the machine harness connector J2 for the ECM, measure the resistance from contact J2-3 (wire A975-BU(Blue)) to all of the