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2.4L Hybrid



DTC P0751 or P0752 (2.4L Hybrid)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptors
DTC P0751
- 1-2 Shift solenoid (SS) Valve Performance - No First or Fourth Gear

DTC P0752
- 1-2 Shift solenoid (SS) Valve Performance - No Second or Third Gear




Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The 1-2 shift solenoid (SS) valve and the 2-3 SS valve are supplied with fused ignition voltage. The ground path is controlled by the transmission control module (TCM). When the TCM commands the solenoid OFF, a ground path is not provided and the filtered line pressure that is fed to the solenoid is exhausted. When the TCM commands the solenoid ON, a ground path is provided and the exhaust port is blocked, stopping the exhaust of line pressure. The TCM identifies a 1-2 SS valve or a 2-3 SS valve condition by monitoring the commanded gear versus gear ratio. Refer to Shift Solenoid Valve State and Gear Ratio (4T45-E).


Conditions for Running the DTC


P0751
* No TP sensor DTCs P0121, P0122, or P0123.
* No ISS DTCs P0716 or P0717.
* No OSS DTCs P0722 or P0723.
* No TCC system stuck ON DTC P0742.
* No 1-2 SS valve electrical DTCs P0973 or P0974.
* No 2-3 SS valve electrical DTCs P0976 or P0977.
* The calc. throttle position is 8 percent or more.
* The transmission ISS is 150 RPM or more.
* The transmission OSS is 200 RPM or more.
* The time since the last gear change is 1 second.
* The engine speed is greater than 500 RPM for 2 seconds.
* The transmission fluid temperature is between 20-130°C (68-266°F).
* The engine torque is greater than 50 N.m (37 lb ft).



P0752
* No TP sensor DTCs P0121, P0122, or P0123.
* No ISS DTCs P0716 or P0717.
* No OSS DTCs P0722 or P0723.
* No TCC system stuck ON DTC P0742.
* No 1-2 SS valve electrical DTCs P0973 or P0974.
* No 2-3 SS valve electrical DTCs P0976 or P0977.
* The calc. throttle position is 8 percent or more.
* The transmission ISS is 150 RPM or more.
* The transmission OSS is 200 RPM or more.
* The engine torque is greater than 50 N.m (37 lb ft).
* The time since the last gear change is 1 second.
* The engine speed is greater than 500 RPM for 2 seconds.
* The transmission fluid temperature is between 20-130°C (68-266°F).



Conditions for Setting the DTC

P0751

The following conditions both occur twice in one trip:

P0751 - Condition 1

The TCM commands 1st gear and the gear ratio indicates 2nd gear, 1.54:1 to 1.71:1. for 2 seconds.

P0751 - Condition 2

The TCM commands 4th gear and the gear ratio indicates 3rd gear, 0.95:1 to 1.05:1, for 4 seconds.

P0752

The following conditions both occur twice in one trip:

P0752 - Condition 1

The TCM commands 2nd gear and the gear ratio indicates 1st gear, 2.81:1 to 3.11:1 for 2 seconds.

P0752 - Condition 2

The TCM commands 3rd gear and the gear ratio indicates 4th gear, 0.65:1 to 0.72:1, for 3 seconds.


Action Taken When the DTC Sets


P0751
* DTC P0751 is a Type B DTC.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The Hybrid control module (HCM) inhibits Hybrid operation.



P0752
* DTC P0752 is a Type B DTC.
* The TCM inhibits 3-2 downshifts when the vehicle speed is greater than 52 km/h (32 mph).
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The TCM forces the TCC ON.
* The Hybrid control module (HCM) inhibits Hybrid operation.



Conditions for Clearing the DTC

DTCs P0751 and P0752 are Type B DTCs.


Diagnostic Aids

If the DTC is cleared, then will not reset when the vehicle is driven, some of the following conditions may exist:

* Fluid contamination
* Plugged fluid circuits
* Restricted fluid circuits
* Inspect transmission fluid lines to radiator. Lines may be pinched, plugged or twisted.
* Refer to Shift Solenoid Valve State and Gear Ratio (4T45-E).
* Internal damage to the torque converter may prevent TCC application.
* It is possible for an internal TCM failure which may not allow sufficient current to operate the solenoids. Verify TCM functionality by commanding the suspected solenoid ON/OFF using the scan tool and listen for a click.



Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (MN5) (Electrical Diagrams)Automatic Transmission Controls Schematics (ME7) (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information


Circuit/System Verification

1. Perform the Transmission Fluid Check (4T45-E Automatic Transaxle) to verify correct fluid level and condition. The transmission fluid level should be within the crosshatch band and the transmission fluid should be red or dark brown.

• If the transmission fluid is low or discolored, refer to Automatic Transmission Fluid Filter and Seal Replacement (Service and Repair).

2. Operate the vehicle in Drive and ensure that the TCM commands all gears. The ratios should match the commanded gear for all gears. Refer to Shift Solenoid Valve State and Gear Ratio (4T45-E).

• If the gear ratios do not match the commanded gear, inspect the following and repair/replace as necessary:


* Inspect the shift solenoid/hydraulic circuit for an internal malfunction.
* Damaged seals on the shift solenoid valve. Refer to Shift Solenoid Leak Test (Shift Solenoid Leak Test) for further diagnosis.

3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.

* Allow the transmission to operate through all gears and all the TCC to engage. Ensure that the gear ratios match each commanded gear and the TCC slip speed is less than 55 RPM when the TCC is commanded ON.
* Shift Solenoid Leak Test (Shift Solenoid Leak Test)
* 1-2 Shift Solenoid Valve Replacement (1-2 Shift Solenoid Valve Replacement)
* Control Valve Body Disassemble (Overhaul)
* Control Valve Body Cover Removal (Overhaul)and Side Cover/Gaskets, Disassemble, Assemble, Install (Overhaul)


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