D250E Series II, D300E Series II, D350E Series II and D400E Series II Articulated Trucks Power Train Electronic Control System Caterpillar

Illustration 1	g00485874
Schematic Of The Center/Rear Differential Lock Solenoid Valve

This diagnostic code is recorded when the ECM reads the current of the solenoid circuit as above normal (short to ground).

The possible causes for this diagnostic code are listed:

• The circuit of the solenoid is shorted to ground.

• The solenoid has failed.

• The ECM is faulty. This is unlikely.

The nominal resistance of the coil at room temperature is 34 ohms.

1. CHECK THE SOLENOID.

   1. Turn the disconnect switch and the key start switch to the ON position.

   2. Ensure that CID 0970 FMI 06 for the solenoid is on-hold.

   3. Observe the status of the "SERV CODE" indicator.

   4. Disconnect the machine harness from the solenoid.

      Expected Result: The "SERV CODE" is no longer showing when the solenoid is disconnected.

      Results:

      • YES - The SERV CODE is no longer showing when the solenoid is disconnected. The circuit is correct. The solenoid has failed. Repeat this test "CHECK THE SOLENOID" in order to verify that the solenoid has failed. Replace the solenoid. STOP.

      • NO - The diagnostic code remains. Proceed to 2.

2. CHECK THE SOLENOID CIRCUIT FOR A SHORT TO GROUND.

   1. Turn the key start switch and the disconnect switch to the OFF position.

   2. Disconnect the machine harness from the solenoid.

   3. Disconnect the machine harness connectors J1 and J2 from the ECM.

   4. At machine harness connector J1 and J2, measure the resistance from the signal contact J2-8 (wire K745-YL) to all possible sources of ground. The possible sources of ground are listed: J1-2 (wire 202-BK), J1-5 (wire 202-BK), J1-7 (wire F789-PU), J2-3 (wire F790-PK) and frame ground.

      Expected Result: The resistance should be greater than 5000 ohms for each measurement.

      Results:

      • YES - The resistance is correct. The machine harness is correct. Proceed to 3.

      • NO - There is a short in the machine harness. The short is between wire (K745-YL) and the circuit with the low resistance measurement. Repair the harness or replace the harness. STOP.

3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

   1. Inspect the contacts and clean the contacts of the harness connectors.

   2. Reconnect all harness connectors.

   3. Turn the key start switch and the disconnect switch to the ON position.

   4. Enter service mode of the Caterpillar Monitoring System and clear all inactive diagnostic codes.

   5. Operate the machine.

   6. Observe the status of CID 0970 FMI 06 for the solenoid. The "SERV CODE" is NOT showing.

      Expected Result: The CID 0970 FMI 06 for the solenoid is NOT present. The "SERV CODE" is NOT showing.

      Results:

      • YES - The diagnostic code is NOT present. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation. STOP.

      • NO - The diagnostic code has not been corrected. It is unlikely that the ECM is faulty. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Testing And Adjusting, "Electronic Control Module (ECM) - Replace". STOP.