For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0756: 2-3 Shift Solenoid (SS) Valve Performance - No First or Second Gear
DTC P0757: 2-3 Shift Solenoid (SS) Valve Performance - No Third or Fourth Gear

### Diagnostic Fault Information

Hydraulic Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
1-2 SS Valve | -- | -- | -- | P0751, P0752
2-3 SS Valve | -- | -- | -- | P0756, P0757
TCC PWM Valve | -- | -- | -- | P0741, P0742

### Typical Scan Tool Data

#### 2-3 Shift Solenoid (SS) Valve Performance Parameter Data

Circuit | Normal | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | --- | ---
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: OK
1-2 Sol. CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts
2-3 Sol. CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts
TCC Duty Cycle CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts

### Circuit/System Description

The transmission control module (TCM) controls the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is fully applied, the engine is coupled directly to the transmission through the TCC. The TCC used is an electronically controlled capacity clutch (ECCC). The TCM will normally allow a small amount of slip to occur with the ECCC. When the TCC is engaged, TCC slip speed is maintained at approximately 20-50 RPM. 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 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 .

### Conditions for Running the DTC

#### P0756

• | 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 5 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).

#### P0757

• | 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 40 N·m (29 lb ft) or more when 3rd gear is commanded.

• | The time since the last gear change is 1 second.

• | The engine speed is greater than 500 RPM for 5 seconds.

• | The transmission fluid temperature is between 20-130°C (68-266°F).

### Conditions for Setting the DTC

#### P0756

The following conditions both occur twice in one trip:

#### P0756 - Condition 1

The TCM commands 1st gear with the transmission OSS 200 RPM or more, the TCC slip speed is -20 RPM or more, and the gear ratio indicates 4th gear, 0.65:1 to 1.87:1, for 2 seconds.

#### P0756 - Condition 2

The TCM commands 2nd gear and the gear ratio indicates 3rd gear, 0.95:1 to 1.05:1, for 3 seconds.

#### P0757

The following conditions both occur twice in one trip:

#### P0757 - Condition 1

The TCM commands 3rd gear and the gear ratio indicates 2nd gear, 1.54:1 to 1.71:1 for 2 seconds.

#### P0757 - Condition 2

The TCM commands 4th gear and the gear ratio indicates 1st gear, 1.54:1 to 3.11:1, for 2 seconds.

### Action Taken When the DTC Sets

#### P0756

• | DTC P0756 is a Type A DTC.

• | The TCM inhibits 1st gear.

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

#### P0757

• | DTC P0757 is a Type A DTC.

• | The TCM inhibits 4th gear.

• | The TCM forces the TCC ON.

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTCs P0756 and P0757 are Type A 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

• | 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.

• | Refer to Shift Solenoid Valve State and Gear Ratio .

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Perform the Transmission Fluid Check 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 .

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 .

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

• | Debris or chips in the accumulator and actuator feed oil passages.

• | Debris or chips restricting oil flow in passage #29 of the case or through the spacer plate gasket into the valve body

• | A cracked 2-3 shift solenoid

• | A 2-3 shift valve which is stuck or hung up in the valve body bore

• | A 2-3 shuttle valve which is stuck or hung up in its bore

• | Damaged seals on the shift solenoid valves. Refer to 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 after completing the repair.

• | Shift Solenoid Leak Test

• | 2-3 Shift Solenoid Valve Replacement

• | Control Valve Body Disassemble

• | Control Valve Body Cover Removal and Side Cover/Gaskets, Disassemble, Assemble, Install