CX31 On-Highway Transmission Caterpillar

Note: The troubleshooting information is intended to aid in diagnosing a given problem. The possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved.

Prior to carrying out troubleshooting on the retarder, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System ECM".

If fault codes are present, repair the cause of the fault code.

If any problems have been encountered with the retarder, first attempt to recalibrate the retarder. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, "Transmission Fill - Calibrate".

The Retarder Will Not Engage

Possible Cause

1. The control switch for the retarder is not functioning correctly.

   • Check the operation of the control switch for the retarder. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test" and refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

2. The wiring harness for the power train may be damaged.

   • Check the wiring and check the connector for damage. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Repair any damage that is found in the wiring harness, or replace any loose connections that are found.

3. The hoses or the lines in the power train hydraulic system may be damaged.

   • Inspect the condition of the lines. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

4. The power train oil level is lower than the specification.

   • Check the power train oil level. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Check the pressures in the power train. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

5. There is debris and damaged components in the power train.

   • Inspect the oil filter for debris.

   • Determine the origin of the debris and repair the damaged component.

   • Change the oil in the power train and install a new oil filter.

   • Replace the lockup clutch and transmission modulating clutch valves.

   • Flush the oil cooler and external lines.

6. There may not be sufficient pressure at the retarder actuation valve.

   • Check the pressure of the oil in the retarder actuation valve. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

7. There may not be sufficient pressure at the retarder hydraulic control valve.

   • Check the relief pressure for the torque converter outlet. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

8. The pressure of the oil in the transmission hydraulic control system may not be within the specification.

   • Test the pressures of the oil in the transmission hydraulic control system. Make any necessary repairs or adjustments. Refer to Specifications, Systems Operation/Testing and Adjusting, "Transmission Oil Supply".

9. The solenoid on the retarder actuation valve is not functioning correctly.

   • Test the solenoid for correct operation. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

10. The retarder hydraulic control valve is not functioning correctly.

    • Check that the retarder actuation valve for the retarder hydraulic control valve is working correctly. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

    • Check the pressure to the retarder hydraulic control valve. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

    • The springs in the retarder hydraulic control valve may be weak or broken. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

    • Check that the spool in the retarder hydraulic control valve is not sticking. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

The Retarder Will Not Disengage

Possible Cause

1. The control switch for the retarder is not functioning correctly.

   • Check the operation of the control switch for the retarder. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test" and refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

2. The solenoid on the retarder actuation valve is not functioning correctly.

   • Test the solenoid for correct operation. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

3. The retarder hydraulic control valve is not functioning correctly.

   • Check the pressure to the retarder hydraulic control valve. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

   • The springs in the retarder hydraulic control valve may be weak or broken. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

   • Check that the spool in the retarder hydraulic control valve is not sticking. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

The Retarder Does Not Operate Correctly

Possible Cause

1. The wiring harness for the power train may be damaged.

   • Check the wiring and check the connector for damage. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Repair any damage that is found in the wiring harness, or replace any loose connections that are found.

2. The hoses or the lines in the power train hydraulic system may be damaged.

   • Inspect the condition of the lines. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

3. The power train oil level is lower than the specification.

   • Check the power train oil level. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Check the pressures in the power train. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

4. The pressure of the oil in the transmission hydraulic control system may not be within the specification.

   • Test the pressures of the oil in the transmission hydraulic control system. Make any necessary repairs or adjustments. Refer to Specifications, Systems Operation/Testing and Adjusting, "Transmission Oil Supply".

5. The control switch for the retarder is not functioning correctly.

   • Check the operation of the control switch for the retarder.

6. There is debris and damaged components in the power train.

   • Inspect the oil filter for debris.

   • Determine the origin of the debris and repair the damaged component.

   • Change the oil in the power train and install a new oil filter.

   • Replace the lockup clutch and transmission modulating clutch valves.

   • Flush the oil cooler and external lines.

7. The solenoid on the retarder actuation valve is not functioning correctly.

   • Test the solenoid for correct operation. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

8. The retarder hydraulic control valve is not functioning correctly.

   • Check the pressure to the retarder hydraulic control valve. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Pressures".

   • The springs in the retarder hydraulic control valve may be weak or broken. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".

   • Check that the spool in the retarder hydraulic control valve is not sticking. Refer to Specifications, Systems Operation/Testing and Adjusting, "Retarder - Test".