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

Illustration 1	g00483589
Schematic Of The Position Sensor For The Shift Lever

This diagnostic code is recorded when the ECM reads the signal voltage of the position sensor as being too low.

The possible causes of this diagnostic code are listed:

• Wire M997-PU is shorted to the solenoid return (J1-15).

• The sensor is faulty.

• The ECM is faulty. This is unlikely.

Note: If the machine is shut down and the diagnostic code is active, the machine will NOT start again until the diagnostic code has been cleared. In order for the machine to start, the sensor must indicate the NEUTRAL position.

The results of this diagnostic code are listed:

• The machine will not shift.

• The transmission will remain in the current gear.

• The solenoid for the lockup clutch solenoid will disengage.

1. CHECK THE SENSOR.

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

   2. Ensure that the diagnostic code is active.

   3. Observe the status of the diagnostic code. Disconnect the machine harness from the sensor.

      Expected Result: The diagnostic code will remain active if the sensor is not the cause of the diagnostic code. The sensor is the cause of the diagnostic code if the diagnostic code is NO longer active.

      Results:

      • OK - The diagnostic code remains active. The sensor is not faulty. The machine harness may be faulty or the ECM may be faulty. Proceed to 2.

      • NOT OK - The diagnostic code is NO longer active. The machine harness and the ECM are operating properly. The sensor is faulty. Replace the sensor. STOP.

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

   1. The sensor remains disconnected from the machine harness.

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

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

   4. At the machine harness connector J1, measure the resistance from contact J2-5 (M997-PU) to all source of ground. The sources of ground are contacts: 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.

      Results:

      • OK - The resistance is greater than 5000 ohms. The machine harness is correct. Proceed to 3.

      • NOT OK - The resistance is less than 5000 ohms. There is a short in the machine harness. The short is between the signal circuit (wire M997-PU) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness. STOP.

3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

   1. Clean the contacts of the harness connectors.

   2. Reconnect all harness connectors.

   3. Observe the status of the diagnostic code.

   4. Operate the machine.

   5. Observe the status of the diagnostic code.

      Expected Result: The diagnostic code is NO longer active.

      Results:

      • YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection and/or a short at one of the harness connectors that was disconnected and then reconnected. Resume normal machine operation. STOP.

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