TH48-E80 Petroleum 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, RENR5628, "Power Train Electronic Control System".

Note: Modulating reducing style and ECPC style lock up clutch valves require software with different application codes. Refer to Special Instruction, REHS4541, "Software Configuration Guide{3168, 4800, 4808, 7600, 7610, 7620}".

Check transmission pressures for accuracy if any of the following conditions occur:

• The quality of transmission shifts has degraded.

• A new ECM has been installed.

• A new wiring harness has been installed.

• The transmission has been rebuilt with new clutches.

• The engine has been rebuilt.

• The transmission has been installed behind a new engine.

If any transmission components have been replaced, operate the component at least 12 times prior to adjusting transmission pressures.

Refer to Specifications, Systems Operation/Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

Troubleshooting the Transmission

The Machine Will Not Pump

Possible Cause

1. The transmission control may be faulty.

   • Test the transmission control for correct operation. Refer to Testing and Adjusting, "Pilot Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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 Specifications, Systems Operation/Testing and Adjusting, "Relief Valve (Transmission Hydraulic Control) - Test and Adjust".

4. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

5. The wiring harness for the power train 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.

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, SEBU8133, "Changing Speed and Direction" and Software Configuration Guide, REHS4541.

3. The transmission oil may be cold.

   • Check the temperature of the transmission oil.

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

   • Activate the transmission warmup feature, if equipped.

4. There may be a fault in the transmission ECM.

   • Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR5628, "Power Train Electronic Control System".

5. The transmission may be operating in an elevated shift mode due to a fault in the circuits.

   • Check the wiring harness for damage or for possible short circuits. Refer to Specifications, Systems Operation, Testing and Adjusting, "Visual Inspection".

   • Use Caterpillar ET in order to check for faults in the electrical circuits. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, KENR5628, "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. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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, RENR5628, "Power Train Electronic Control System".

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, "Pilot Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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 Specifications, Systems Operation/Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

12. 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, RENR9664, "Transmission Planetary - Disassemble and Assemble".

    • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, RENR9664, "Transmission Planetary - Disassemble and Assemble".

    • Check the springs in the clutches. Refer to Specifications for the correct specifications for the springs in the transmission 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 Operation and Maintenance Manual, SEBU8133, "Torque Converter and Transmission Oil Level - Check".

2. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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 Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

4. Pressure in the engaged clutches may be below specification.

   • Check the pressure of the oil in the clutch under full engagement. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

5. 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, RENR9664, "Transmission Planetary - Disassemble and Assemble".

   • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, RENR9664, "Transmission Planetary - Disassemble and Assemble".

   • Check the springs in the clutches. Refer to Specifications for the correct specifications for the springs in the transmission clutches.

6. 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 Operation and Maintenance Manual, SEBU8133, "Torque Converter and Transmission Oil Level - Check".

2. The machine may have been operated incorrectly.

   • Operate the machine in the correct manner. Refer to Operation and Maintenance Manual, SEBU8133.

3. The temperature sensors in the transmission hydraulic control system may not be functioning correctly.

   • Use Caterpillar 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 Pressures for Control Manifold − Testing and Adjusting".

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, "Leakage From the Lockup Clutch (Torque Converter) − Test".

   • Refer to Testing and Adjusting, "Relief Pressures for Control Manifold − Testing and Adjusting"

   • Refer to Testing and Adjusting, "Primary Pressures for the Lockup Clutch and Solenoid Valve (Torque Converter) − Test".

   • The software or application code may be incorrect. Modulating reducing style and ECPC style lock up clutch valves require software with different application codes. Refer to Special Instruction, REHS4541, "Software Configuration Guide{3168, 4800, 4808, 7600, 7610, 7620}"

7. The torque converter inlet pressure is outside specifications.

   • Check the torque converter inlet pressure. Refer to Specifications, Systems Operation/Testing and Adjusting, "Relief Pressures for Control Manifold − Testing and Adjusting".

   • Replace the torque converter inlet relief valve. Refer to Disassembly and Assembly, RENR9664, "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 Pressures for Control Manifold − Testing and Adjusting".

   • Replace the torque converter outlet relief valve. Refer to Disassembly and Assembly, RENR9664, "Power Train".

9. Pressure in the engaged clutches may be below specification.

   • Check the pressure of the oil in the clutch under full engagement. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

10. 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 Operation and Maintenance Manual, SEBU8133, "Torque Converter and Transmission Oil Level - Check".

2. 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, "Pilot Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

3. Pressure in the engaged clutches may be below specification.

   • Check the pressure of the oil in the clutch under full engagement. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

4. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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 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. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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, "Pilot Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

4. The transmission oil level is outside the specification.

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

5. 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 Specifications, Systems Operation/Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

6. 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.

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, RENR9664, "Power Train".

   • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, RENR9664, "Power Train".

   • Check the springs in the clutches. Refer to Specifications, Systems Operation/Testing and Adjusting, "Power Train Specifications" for the correct specifications for the springs in the transmission clutches.

Troubleshooting Transmission Pressures

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, SEBU8133, "Torque Converter and Transmission Oil Level - Check".

2. The transmission oil pressure may be outside the specification.

   • Check the pressure of the oil from the transmission pump and adjust the pressure of the system if necessary. Refer to Specifications, Systems Operation, Testing and Adjusting, "Pressure for Transmission Oil Pump − 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, RENR5628, "Electronic Control Module (ECM) − Flash Program".

   • Check for the correct software application code with Caterpillar ET. Modulating reducing style and ECPC style lock up clutch valves require software with different application codes. Refer to Special Instruction, REHS4541, "Software Configuration Guide{3168, 4800, 4808, 7600, 7610, 7620}".

4. There may be a leakage around the valves for the clutch pressure control.

   • Check the area around the valves for the 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 Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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

   • Check the temperature of the oil. If the oil temperature is above the specific limit, consult your local Caterpillar dealer.

6. The transmission oil temperature sensor may not function correctly.

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

   • Test the transmission oil temperature sensor. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR5628, "Power Train Electronic Control System".

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, RENR5628, "Power Train Electronic Control System".

8. Clutch pressure may be incorrect.

   • Test the oil pressure in the clutches for the transmission. Refer to Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

   • The software or application code may be incorrect. Modulating reducing style and ECPC style lock up clutch valves require software with different application codes. Refer to Special Instruction, REHS4541, "Software Configuration Guide{3168, 4800, 4808, 7600, 7610, 7620}".

9. There may be a fault in the transmission ECM.

   • Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR5628, "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, SEBU8133, "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 Specifications, Systems Operation, Testing and Adjusting, "Clutch Pressure for Transmission Hydraulic Control Valve − Test and Adjust".

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, RENR9664, "Power Train".

    • Check that the disks and the plates are within the specified dimensions. Refer to Disassembly and Assembly, RENR9664, "Power Train".