CX35 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 torque converter, 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".

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

The Torque Converter or the Transmission is Overheating

Possible Cause

1. The transmission may have been operated incorrectly.
   • Operate the transmission in the correct manner. Refer to the Operation and Maintenance Manual, SEBU8203.

2. The temperature sensors in the transmission hydraulic control system may not be functioning correctly.
   • Use ET in order to determine whether there are any faults with the temperature sensors.

3. The power train oil level is lower than the specification.
   • Check the transmission oil level. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

4. There is debris and damaged components in the transmission.
   • Inspect the oil filter for debris.

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

   • Change the oil in the transmission and install a new oil filter.

5. The coolant flow through the transmission oil cooler is below the specification.

6. The oil flow through the transmission oil cooler is below the specification.
   • Check the oil pressure to the transmission oil cooler. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Torque Converter Outlet) Pressure - Test".

7. The torque converter inlet pressure is outside specifications.
   • Check the torque converter inlet pressure and the torque converter inlet relief valve. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Torque Converter Inlet) Pressure - Test".

8. The torque converter outlet pressure is outside specifications.
   • Check the torque converter outlet pressure. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Torque Converter Outlet) Pressure - Test".

9. The torque converter is worn or damaged.
   • Inspect the components of the torque converter for wear or damage. Refer to Disassembly and Assembly, KENR6060, "Torque Converter - Disassemble and Assemble".

10. The torque converter lockup clutch is not functioning.
    • Test the correct function of the torque converter lockup clutch. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

The Torque Converter Lockup Clutch Does Not Disengage and the Engine Dies at Low Speed

Possible Cause

1. There is debris and damaged components in the transmission.
   • Inspect the oil filter for debris. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

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

   • Change the oil in the transmission and install a new oil filter.

2. The solenoid on the modulating valve (torque converter lockup clutch) does not function correctly.
   • Check the operation of the solenoid before the engine start switch is turned off. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

3. The shuttle valve in the modulating valve (torque converter lockup clutch) may be sticking.
   • Check the operation of the modulating valve (torque converter lockup clutch). Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

4. There may be insufficient oil pressure in the torque converter in order to return the piston for the torque converter lockup clutch to the open position.
   • Check the relief pressures of the oil in the torque converter. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Torque Converter Outlet) Pressure - Test" and Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Torque Converter Inlet) Pressure - Test".

5. The piston in the torque converter lockup clutch may be sticking.
   • Check the oil pressure in the torque converter lockup clutch. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

   • Check the condition of the piston in the torque converter lockup clutch. Refer to Disassembly and Assembly, KENR6060, "Torque Converter - Disassemble and Assemble" for the CX31.

The Torque Converter Lockup Clutch Does Not Engage

Possible Cause

1. The wiring harness for the transmission may be damaged.
   • Check the wiring and check the connectors 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 transmission oil level is below the specification.
   • Check the transmission oil level. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

3. There is debris and damaged components in the transmission.
   • Inspect the oil filter for debris.

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

   • Change the oil in the transmission and install a new oil filter.

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, "Relief Valve (Transmission Hydraulic Control) - Test and Adjust".

5. The solenoid on the modulating valve (torque converter lockup clutch) does not function correctly.
   • Check the operation of the solenoid before the engine start switch is turned off. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

6. The shuttle valve in the modulating valve (torque converter lockup clutch) may be sticking.
   • Check the operation of the modulating valve (torque converter lockup clutch). Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

7. The components in the torque converter lockup clutch may be worn.
   • Check the oil pressure in the torque converter lockup clutch. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

   • Check the condition of the piston in the torque converter lockup clutch. Refer to Disassembly and Assembly, "Torque Converter - Disassemble and Assemble".

The Machine Will Not Move With A Full Load

Possible Cause

1. There is a fault with the freewheel clutch in the torque converter or the freewheel clutch is incorrectly assembled.
   • Check that the freewheel clutch is correctly installed.