P0731

DTC P0731

Circuit Description
While driving in 1st gear, line pressure is supplied to the 1st clutch piston, the 1st clutch engages and the shaft and 1st gear rotate together to transmit drive force. The oil pressure is supplied to the 1st clutch via the suction filter, oil pump, main regulator, manual valve, shift valve, feed pipe and clutch piston. The powertrain control module (PCM) calculates the automatic transmission input shaft speed (AT ISS) sensor to automatic transmission output shaft speed (AT OSS) sensor ratio. When the calculated ratio is incorrect for 1st gear, while the PCM is commanding 1st gear, the PCM determines it is a fault and DTC P0731 sets. DTC P0731 is a type C DTC.

Conditions for Running the DTC
- No ECT DTCs P0116, P0117, or P0118.
- No TP DTCs P0122, P0123, P0222, or P0223.
- No VSS DTCs P0501, P0502, or P0503.
- No TR Switch DTCs P0705 or P0706.
- No AT ISS DTCs P0716, P0717, or P0718.
- No Clutch PC Performance DTCs P0746, P0747, P0776, or P0777.
- No SS Valve Performance DTCs P0751, P0752, P0756, P0761, P0757, or P0762.
- No Incorrect Shift Pattern DTC: P0780.
- No Clutch PC Solenoid Electrical DTCs P0962 or P0963.
- No Clutch PC Solenoid 2 DTCs P0966 or P0967.
- No SS 1 DTCs P0973 or P0974.
- No SS 2 DTCs P0976 or P0977.
- No SS 3 DTCs P0979 or P0980.
- No TAC DTCs P2101, P2108, or P2553.
- No APP DTC P2122, P2123, P2127, P2128, P2135, or P2138.
- No Minimum Idle Position DTC P2176.
- No TCC PC Solenoid DTCs P2763 or P2764.
- No TCC Enable Solenoid DTCs P2769 or P2770.
- No TAC Communication DTC U0107.
- The system voltage is 11 volts or greater.
- The vehicle speed is 2 km/h (1 mph) 12 km/h (8 mph).
- The engine speed is 1,000 RPM or greater.
- The transmission is in D, 1, or L range.

Conditions for Setting the DTC
- The actual gear ratio is 1.2 times greater than, or 0.75 times less than the known 1st gear ratio for 12 seconds or greater.
- The vehicle speed calculated from mainshaft speed sensor is more than 11 km/h (7 mph) while the vehicle speed calculated from the countershaft speed sensor is less than 2 km/h (1 mph) for 3 seconds or more.
- The actual gear ratio is correct to the known gear ratio for 3 seconds or more.

Action Taken When the DTC Sets
- The PCM does not illuminate the malfunction indicator lamp (MIL).
- The PCM illuminates the service vehicle soon (SVS) lamp during the second consecutive trip in which the Conditions for Setting the DTC are met.
- The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
- The PCM stores DTC P0731 in PCM history.

Conditions for Clearing the SVS Lamp/DTC
- The PCM turns OFF the SVS lamp when the condition no longer exists.
- A scan tool can clear the SVS lamp/DTC.
- The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
- The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids
- Inspect for a shift control system malfunction.
- Inspect for a worn 1st clutch.
- Inspect for an insufficient automatic transmission fluid pump output.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step tests for low fluid level, which may cause slipping and result in an incorrect gear ratio.
4. This step verifies that the correct gear ratios occur for commanded gears.
5. This step tests for low line pressure.

Steps 1 - 7:

Steps 8 - 9:

DTC P0731