P0751

CIRCUIT DESCRIPTION

The Powertrain Control Module (PCM) identifies a 1-2 shift solenoid valve problem by monitoring the commanded gear versus gear ratio.

If the PCM detects a gear ratio that is outside the limits for a particular commanded gear, then DTC P0751 sets. DTC P0751 is a Type A DTC.

CONDITIONS FOR SETTING THE DTC

^ No MAF DTCs P0101, P0102 or P0103 are set.
^ No Throttle Position (TP) sensor DTCs P0121, P0122 or P0123 are set.
^ No Vehicle Speed (VSS) sensor DTCs P0502 or P0503 are set.
^ No Automatic Transmission Input Speed Sensor (A/T ISS) DTCs P0716 or P0717 are set.
^ No 1-2 shift solenoid valve electrical DTC P0753 is set.
^ No 2-3 shift solenoid valve electrical P0758 is set.
^ No Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) DTC P1810 is set.
^ No TCC Pulse Width Modulation (PWM) Solenoid valve DTC P1860 is set.
^ The engine has been running for more than 5 seconds.
^ Not in fuel cut off.
^ The vehicle speed is greater than 6 km/h (4 mph).
^ A shift is not in progress.
^ The throttle angle is greater than 11°.
^ The transmission fluid temperature is greater than -18°C (0°F).
^ The TFP Val. Position Sw. indicates D1, D2, D3 or D4.

Failure Criteria

Case 1
^ First gear is commanded.
^ The gear ratio is 1.54-1.71 for 1 second.
^ Delivered torque is greater than 82 Nm (60 lb. ft).

Case 2
^ Second gear is commanded.
^ The gear ratio is 2.87-3.11 for 3 seconds.
^ Delivered torque is greater than 96 Nm (70 lb. ft).

Case 3
^ Third gear is commanded.
^ The gear ratio is 0.65-0.71 for 3 seconds.
^ Delivered torque is greater than 82 Nm (60 lb. ft).

Case 4
^ Fourth gear is commanded.
^ The gear ratio is 0.95-1.05 for 5 seconds.
^ Delivered torque is greater than 96 Nm (70 lb. ft).

ACTION TAKEN WHEN THE DTC SETS

^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the Driver Information Center (DIC).
^ The PCM commands 2nd gear.
^ The PCM commands default line pressure
^ The PCM disables steady state adapts
^ The PCM disables garage shift adapts
^ The PCM inhibits Torque Converter Clutch.
^ The PCM inhibits torque management.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS

^ Inspect the transmission fluid for sediment.
^ Inspect the transmission filter for debris.
^ Refer to the Shift Solenoid Valve State and Gear Ratio table.

TEST DESCRIPTION

Important: Do not drive the vehicle for an extended period of time, because additional internal damage may occur.

The numbers below refer to the step numbers on the diagnostic table.

3. This step verifies that DTC P0751 is set. Set up data pairs (current gear and gear ratio) on the scan tool. Drive the vehicle while commanding First gear with the scan tool.
4. This step verifies that the gear ratio indicated a Second gear start, and the vehicle does not achieve First gear. The list of components should be inspected and repaired if faulty.
6. This step verifies that the gear ratio indicates Third gear and the vehicle does not achieve Fourth gear. The list of components should be inspected and repaired if faulty.
8. This step verifies that the gear ratio indicates First gear and the vehicle does not achieve Second gear. The list of components should be inspected and repaired if faulty.
10. This step verifies that the gear ratio indicates Fourth gear and the vehicle does not achieve Third gear. The list of components should be inspected and repaired if faulty.