CX35 On-Highway Transmission Caterpillar

Note: The troubleshooting information is given 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 transmission planetary group, 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".

Calibrate the transmission if any of the following conditions occur:

• The quality of transmission shifts has degraded.

• Modulating valves for the electronic clutch pressure control have been replaced.

• A new ECM has been installed.

• A new wiring harness has been installed.

• A repair has been carried out to a wire to the modulating valves for the electronic clutch pressure control.

• The transmission has been rebuilt with new clutches.

• The mating engine has been rebuilt.

• The transmission has been installed behind a new engine.

Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Transmission Fill - Calibrate".

Troubleshooting the Transmission

The Machine Will Not Move

Possible Cause

1. The transmission control may be faulty or the transmission control may require calibration.
   • Test the transmission control for correct operation and recalibrate the transmission control. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

2. 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".

3. 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 Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

4. One or more modulating valves for the electronic clutch pressure control may not be functioning correctly.
   • Test the modulating valves for the electronic clutch pressure control. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

5. The wiring harness for the power train may be damaged.
   • Check the wiring and check the connectors for damage. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Visual Inspection".

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

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

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

The Transmission Stays in One Gear or The Transmission Will Not Shift Correctly

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 high gear limit for the transmission may have been selected.
   • Check if a high gear limit has been selected. Refer to Operation and Maintenance Manual, SEBU8203, "Transmission Operation Information".

3. The transmission oil may be cold.
   • Check the temperature of the transmission oil.

   • Allow the oil in the transmission to warm up fully.

4. There may be a fault in the transmission ECM.
   • Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

5. The transmission may be operating in an elevated shift mode due to a fault in the circuits for the service brakes, the engine compression brake or the transmission hold.
   • Check the wiring harness for damage or for possible short circuits. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Use ET in order to check for faults in the electrical circuits. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

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

7. The transmission may require recalibrating.
   • Carry out a calibration of the transmission. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Transmission Fill - Calibrate".

8. The torque converter output speed sensor or the transmission output speed sensors may be faulty.
   • Check the connections on the torque converter output speed sensor and on the transmission output speed sensor. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Test the transmission speed sensors. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

   • Check for ECM fault code.

9. 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 components.

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

10. 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".

11. One or more modulating valves for the electronic clutch pressure control may not be functioning correctly.
    • Test the modulating valves for the electronic clutch pressure control. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

12. The seals on the piston in the transmission clutch may be leaking.
    • Check the pressure of the oil in the clutch under full engagement. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

13. There may be damaged components in the clutches for the transmission.
    • Inspect the oil for debris. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

    • Inspect the clutches for damage. Refer to Disassembly and Assembly, KENR6060, "Transmission Planetary - Disassemble and Assemble".

    • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, KENR6060, "Transmission Planetary - Disassemble and Assemble".

    • Check the springs in the clutches.

The Transmission Slips In One or More Gears

Possible Cause

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

2. One or more modulating valves for the electronic clutch pressure control may not be functioning correctly.
   • Test the oil pressure in the clutches for the transmission. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

   • Test the modulating valves for the electronic clutch pressure control. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

3. The seals on the piston in the transmission clutch may be leaking.
   • Check the pressure of the oil in the clutch under full engagement. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

4. There may be damaged components in the clutches for the transmission.
   • Inspect the oil for debris. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Inspect the clutches for damage. Refer to Disassembly and Assembly, KENR6060, "Transmission Planetary - Disassemble and Assemble".

   • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, KENR6060, "Transmission Planetary - Disassemble and Assemble".

   • Check the springs in the clutches.

5. 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 components.

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

The Transmission Is Overheating

Possible Cause

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

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

3. 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.

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

5. 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".

6. There may be a fault in the torque converter lockup clutch that prevents direct drive through the torque converter.
   • Test the function of the torque converter lockup clutch. Refer to Specifications, Systems Operation/Testing and Adjusting, "Modulating Valve (Torque Converter Lockup Clutch) - Test".

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

   • Replace the torque converter inlet relief valve. Refer to Disassembly and Assembly, KENR6060, "Power Train".

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".

   • Refer to Specifications, Systems Operation/Testing and Adjusting, "Transmission Oil Supply".

9. 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.

The Transmission Does Not Shift Smoothly

Possible Cause

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

2. The transmission may require recalibration. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Transmission Fill - Calibrate".
   • Calibrate the transmission.

3. 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 components.

   • 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".

The Transmission Hesitates During Shifting

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. One or more modulating valves for the electronic clutch pressure control may not be functioning correctly.
   • Test the modulating valves for the electronic clutch pressure control. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

3. 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".

4. 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 components.

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

5. The transmission oil level is outside the specification.
   • Check the transmission oil level. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

6. The seals on the piston in the transmission clutch may be leaking.
   • Check the pressure of the oil in the clutch under full engagement. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

7. There may be damaged components in the clutches for the transmission.
   • Inspect the oil for debris. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Inspect the clutches for damage. Refer to Disassembly and Assembly, KENR6060, "Power Train".

   • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, KENR6060, "Power Train".

   • Check the springs in the clutches.

Troubleshooting The Transmission Calibration

Ensure that the following conditions are met when calibration of the transmission is attempted.

• The transmission is in neutral.

• The engine is running at low idle.

• The transmission oil needs to be at a temperature between 70 °C (158 °F) and 75 °C (167 °F).

Clutch at Limit

Possible Cause

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

   • Add oil to the transmission if the oil level is lower than the specification. Refer to Operation and Maintenance Manual, SEBU8203, "Transmission Oil Level - Check".

2. The transmission oil pressure may be outside the specification.
   • Check the pressure of the oil from the transmission pump. Refer to Specifications, Systems Operation/Testing and Adjusting, "Transmission Oil Supply".

   • Adjust the pressure of the system if it is necessary. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Transmission Hydraulic Control) - Test and Adjust".

3. The software in the ECM is not the latest version.
   • Flash the latest software release. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

4. There may be a leakage around the modulating valve for the electronic clutch pressure control.
   • Check the area around the modulating valve for the electronic clutch pressure control for leakage. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Check the pressure in the clutch when the clutch is selected. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

5. The transmission oil temperature may be outside the specified level.
   • Check the temperature of the oil.

6. The transmission oil temperature sensor may not function correctly.
   • Test the transmission oil temperature sensor. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

   • Check the connections on the transmission oil temperature sensor. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

7. The speed sensors for the transmission may not function correctly at low idle.
   • Check the connections on the torque converter output speed sensor and on the transmission output speed sensors. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

   • Test the transmission speed sensors. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

8. The solenoid on the modulating valve for the electronic clutch pressure control is not functioning correctly.
   • Test the solenoid for correct operation. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

9. There may be a fault in the transmission ECM.
   • Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

10. The viscosity of the oil in the transmission may not be correct.
    • Fill the transmission with the correct grade of oil. Refer to Operation and Maintenance Manual, SEBU8203, "Lubricant Viscosities".

11. The seals on the piston in the transmission clutch may be leaking.
    • Check the pressure of the oil in the clutch under full engagement. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

12. There may be damaged plates or disks in the clutches for the transmission.
    • Inspect the oil for debris. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

    • Inspect the clutches for damage. Refer to Disassembly and Assembly, KENR6060, "Power Train".

    • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, KENR6060, "Power Train".

13. The speed sensor for the torque converter output may not function correctly at low idle.
    • Check the connections on the torque converter output speed sensor. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

    • Test the transmission speed sensors for low speed drop out. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System". Repair the faulty speed sensor or replace the faulty speed sensor.

14. The transmission oil temperature sensor may not function correctly.
    • Test the transmission oil temperature sensor. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

    • Check the connections on the transmission oil temperature sensor. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

15. There may be a leakage around the modulating valve for the electronic clutch pressure control.
    • Check the area around the modulating valve for the electronic clutch pressure control for leakage. Refer to Specifications, Systems Operation/Testing and Adjusting, "Visual Inspection".

    • Check the pressure in the clutch when the clutch is selected. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".

16. The solenoid on the modulating valve for the electronic clutch pressure control is not functioning correctly.
    • Test the solenoid for correct operation. Refer to Systems Operation/Troubleshooting/Testing and Adjusting, KENR5099, "Power Train Electronic Control System".