DTC P0731: 1st Gear Incorrect Ratio
- Warm up the engine to normal operating temperature (the radiator fan comes on).
- Make sure that the transmission is filled to the proper level, and check for fluid leaks.
- Drain the ATF (see ATF REPLACEMENT
) through a strainer. Inspect the strainer for metal debris or excessive clutch material.
Does the strainer have metal debris or excessive clutch material?
YES -Replace the transmission, then go to step 12.
NO -Replace the ATF (see step 6 ), then go to step 4.
- Start the engine, run the vehicle in 1st gear in L.
Does the vehicle run in 1st gear in L?
YES -Go to step 5.
NO -Faulty 1st gear one-way clutch. Inspect the 1st gear one-way clutch (see 1ST GEAR ONE-WAY CLUTCH INSPECTION ), then go to step 12.
- Measure the line pressure (see PRESSURE TEST
).
Is the line pressure within the service limit?
YES -Go to step 6.
NO -Replace the main valve body (ATF pump), the regulator valve body (regulator valve), or replace the transmission, then go to step 12.
- Measure the 1st clutch pressure (see PRESSURE TEST
).
Is the 1st clutch pressure within the service limit?
YES -Go to step 7.
NO -Shift valves B and C are stuck. Replace the main valve body and the secondary valve body, or replace the transmission, then go to step 12.
- Turn the ignition switch to ON (II).
- Clear the DTC with the HDS.
- Press the accelerator pedal for 5 seconds at about 3 % throttle. Release the accelerator pedal until the engine speed drops down below 1, 000 rpm. Drive the vehicle in 1st gear for at least 1 second, then press the accelerator pedal so that the transmission upshifts to 2nd gear, then 3rd gear. Slow down, and stop the wheels.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0731 indicated?
YES -Faulty 1st clutch. Replace the 1st clutch, or replace the transmission, then go to step 12.
NO -Go to step 11.
- Monitor the OBD status for P0731 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -Intermittent failure, the system is OK at this time. If any other Pending or Confirmed DTCs were indicated in step 10, go to the INDICATED DTC'S TROUBLESHOOTING .
NO -If the HDS indicates FAILED, faulty 1st clutch. Replace the 1st clutch, or replace the transmission, then go to step 12. If the HDS indicates NOT COMPLETED, go to step 9.
- Press the accelerator pedal for 5 seconds at about 3 % throttle. Release the accelerator pedal until the engine speed drops down below 1, 000 rpm. Drive the vehicle in 1st gear for at least 1 second, then press the accelerator pedal so that the transmission upshifts to 2nd gear, then 3rd gear. Slow down, and stop the wheels.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0731 indicated?
YES -Check for poor connections or loose terminals between the input shaft (mainshaft) speed sensor, the output shaft (countershaft) speed sensor, and the PCM, then go to step 1.
NO -Go to step 14.
- Monitor the OBD status for P0731 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 13, go to the INDICATED DTC'S TROUBLESHOOTING .
NO -If the HDS indicates FAILED, check for poor connections or loose terminals between the input shaft (mainshaft) speed sensor, the output shaft (countershaft) speed sensor, and the PCM, then go to step 5. If the HDS indicates NOT COMPLETED, go to step 12.