120M Series 2, 12M Series 2, 140M Series 2 and 160M Series 2 Motor Graders All Wheel Drive Electronic Control System Caterpillar

Illustration 1	g01377703
Right front drive motor speed sensor circuit

This diagnostic code is recorded when there is no input signal from a right front drive motor speed sensor in the manual mode.

The following conditions could cause this diagnostic code:

• Sensor power wire (T800-OR) open

• Sensor return wire (J767-GY) open

• Sensor return wire (J767-GY) shorted to + battery circuit

• Signal wire (J719-PU) open

• Signal wire (J719-PU) shorted to + battery circuit.

• Signal wire (J719-PU) shorted to ground

• Failed sensor

• Failed right drive pump

• Failed right charge pump

• Low charge pressure

• Failed pump input gears

• Failed pump shaft

• Failed ECM

Test Step 1. VISUALLY VERIFY THAT THE FRONT WHEELS ARE SPINNING

1. Select forward direction. Select maximum "Creep" speed.

2. Select maximum "Creep" speed.

3. Engage AWD "Creep" mode.

4. Lower the blade to lift the front wheels off the ground.

5. Verify that the green AWD indicator is illuminated.

6. Select reverse direction.

7. Select maximum "Creep" speed.

8. Engage AWD "Creep" mode.

9. Lower the blade to lift the front wheels off the ground.

10. Verify that the green AWD indicator is illuminated.

Expected Result:

Both front wheels turn in both forward and reverse directions in "Creep" mode. The green AWD indicator illuminates.

Results:

• NOT OK - Green AWD Indicator does not activate.

  Repair: Check Caterpillar® Electronic Technician (Cat® ET) service tool for other active AWD diagnostics or events. Clear the diagnostic codes that are active.

  Proceed to Test Step 2.

• OK - Both front wheels spin as expected. Proceed to Test Step 2.

• NOT OK - One or both wheels do not spin when commanded in one or both directions. Proceed to Test Step 3.

Test Step 2. CHECK THE SPEED SENSOR

1. Perform the Testing and Adjusting, "Speed Sensor - Test" procedure.

Expected Result:

Speed sensors read correct speed and direction.

Results:

• OK - Speed sensors read correct speed and direction. There is an intermittent open circuit or a short circuit in the speed sensor harness.

  Repair: Repair or replace the harness.

  STOP

• NOT OK - Speed sensors read incorrect speed and direction.

  Repair: See the Troubleshooting, "MID 075 - CID 2322 - FMI 02" Story in this manual. After completing, "MID 075 - CID 2322 - FMI 02", return to this story.

  STOP

Test Step 3. CHECK THE CLUTCH PRESSURE

1. Perform the Testing and Adjusting, "Solenoid Valve (Control Manifold) - Test" procedure.

Expected Result:

Clutch pressure is in the test procedure tolerance.

Results:

• OK - Clutch pressure is in the test procedure tolerance. Proceed to Test Step 4.

• NOT OK - One or more clutch pressures are not in the test procedure tolerance.

  Repair: Correct the clutch pressure.

  Return to Test Step 1.

Test Step 4. CHECK THE PUMP SOLENOID

1. Perform the Testing and Adjusting, "Solenoid Valve (Pump Displacement) - Test" procedure.

Expected Result:

Readings of the pump control pressure are within the test procedure specifications.

Results:

• OK - Readings of the pump control pressure are within the test procedure specifications. Proceed to Test Step 5.

• NOT OK - Readings of the pump control pressure are not within the test procedure specifications.

  Repair: Follow diagnostic steps that are defined in the Test procedure for the Solenoid Valve (Pump Displacement).

  Repeat the Test Step 1 after correcting any problems.

Test Step 5. AUDIBLE CHECK FOR MOTOR SPEED

1. Start the engine.

2. Set engine speed to 800 RPM.

3. Override the left front drive motor solenoid current percentage override command to 100 percent.

   Note: Use Cat® ET to perform this override.

Show/hide table



Illustration 2	g02360876
Cat® ET screen shot

4. Listen at the front axle for the motor spinning.

Expected Result:

Distinct hydraulic motor sound is heard from the AWD motor when the overrides are active. The sound is the motor spinning at high speed.

Results:

• OK - Distinct hydraulic motor sound is heard. The output shaft of the motor or gearbox has failed, in addition to a speed sensor or harness failure.

  Repair: Inspect the motor and the gearbox. Replace the speed sensor, or repair or replace the harness. Replace the motor and the gearbox, if necessary. For information on diagnostic procedures, see the Troubleshooting, "MID 075 - CID 2322 - FMI 02" Story in this manual.

  STOP

• NOT OK - No distinct hydraulic motor sound is heard. There is an error in the hose routing or failure in the mechanically driven pump.

  Repair: Verify that the AWD hose routing and connections are correct. Replace the AWD pumps.

  STOP