P0751
Shift Solenoid Valve State And Gear Ratio:
(A) Shift Solenoid Performance:
(A) Shift Solenoid Performance (continued):
(A) Shift Solenoid Performance:
CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) identifies a 1-2 shift solenoid valve problem by monitoring the commanded gear versus gear ratio.
When the PCM detects a gear ratio that is outside its limits for a particular commanded gear, then DTC PO751 sets. DTC PO751 is a Type A DTC.
CONDITIONS FOR SETTING THE DTC
^ No Mass Air Flow (MAF) DTCs P0101, P0102 or P103 are set.
^ No Throttle Position (TP) DTCs P0121, PO122 or PO123 are set.
^ No Vehicle Speed Sensor (VSS) DTCs PO5O2 or PO5O3 are set.
^ No A/T Input Speed Sensor (ISS) DTCs PO716 or PO717 are set.
^ No 1-2 shift solenoid valve electrical DTC PO753 is set.
^ No 2-3 shift solenoid valve electrical PO758 is set.
^ No Transmission Fluid Pressure (TFP) Sw. DTC P1810 is set.
^ The engine has been running for more than 5 seconds.
^ Not in fuel shut off mode.
^ 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 3O°C (86°F).
^ The Automatic Transmission Fluid Pressure Manual Valve Position switch 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.
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 chart.
1. This Step verifies that the Powertrain On-Board System Check was performed.
2. This Step verifies that the transmission fluid checking procedure was performed.
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.
5. This Step drives the vehicle while commanding a 3-4 shift with the scan tool.
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.
7. This Step drives the vehicle while commanding a 1-2 shift with the scan tool.
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.
9. This Step drives the vehicle while commanding a 2-3 shift with the scan tool.
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.