DTC Troubleshooting

DTC Troubleshooting: P0731

DTC P0731: 1st Gear Incorrect Ratio

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information. How To Troubleshoot A/T Systems

1. Warm up the engine to normal operating temperature (the radiator fan comes on).

2. Make sure that the transmission is filled to the proper level, and check for fluid leaks.

3. Drain the ATF 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 11.

NO - Replace the ATF, ATF Replacement then go to step 4.


4. Measure the line pressure. A/T Pressure Test

Is the line pressure within the service limits?
YES - Go to step 5.

NO - Repair the ATF pump and the regulator valve, or replace the transmission, then go to step 10.


5. Measure the 1st clutch pressure. A/T Pressure Test

Is the 1st clutch pressure within the service limits?
YES - Go to step 6.

NO - Shift valves B and C are stuck. Repair these valves and the related hydraulic circuit, or replace the transmission, then go to step 10.


6. Clear the DTC with the HDS.

7. Start the engine. With the brake pedal pressed, shift to D, and press the accelerator pedal for 5 seconds at about 3 % opened-throttle, then release the accelerator until the engine speed comes down below 1,000 rpm. Release the brake pedal, and 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.

8. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0731 indicated?
YES - Repair the 1st clutch, or replace the transmission, then go to step 10.

NO - Go to step 9.


9. 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 on step 8, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the input shaft (mainshaft) speed sensor, the output shaft (countershaft) speed sensor, and the PCM, then recheck. If the HDS indicates NOT COMPLETED, return to step 7 and recheck.


10. Clear the DTC with the HDS.

11. Start the engine. With the brake pedal pressed, shift to D, and press the accelerator pedal for 5 seconds at about 3 % opened-throttle, then release the accelerator until the engine speed comes down below 1,000 rpm. Release the brake pedal, and 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.

12. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0731 indicated?
YES - Check for poor connections and loose terminals at the input shaft (mainshaft) speed sensor, the output shaft (countershaft) speed sensor, and the PCM, then go to step 1.

NO - Go to step 13.


13. 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 DTCs were indicated on step 12, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the input shaft (mainshaft) speed sensor, the output shaft (countershaft) speed sensor, and the PCM, then go to step 4. If the HDS indicates NOT COMPLETED, return to step 11 and recheck.