For 1990-2009 cars
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

### Circuit Description

The 2-3 Shift Solenoid is fed ignition voltage and the ground path is provided by the Powertrain Control Module (PCM), depending on the solenoids commanded state. When the PCM 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 PCM commands the solenoid ON, a ground path is provided and the exhaust port is blocked, stopping the exhaust of line pressure.

The Powertrain Control Module (PCM) identifies a 2-3 Shift Solenoid Valve (2-3 SS Valve) performance condition by monitoring the commanded gear versus the gear ratio.

If the PCM detects the gear ratio outside the limits for a particular commanded gear, then DTC P0756 sets. DTC P0756 is a Type A DTC.

### Conditions for Setting the DTC

• | No TP DTCs P0121, P0122 or P0123 are set.

• | No VSS DTCs P0502 or P0503 are set.

• | No 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 DTC P0758 is set.

• | No TFP Val. Position Sw. DTC P1810 is set.

• | No TCC PWM Sol. DTC P1860 is set.

• | The engine speed is greater than 500 RPM for 5 seconds, and not in fuel shut off.

• | The Automatic Transmission Fluid Temperature is greater than 20°C (68°F).

• | The transmission is not in Park or Neutral.

• | All of the above conditions are met, and Cases 1 and 2 are true once (stuck OFF), or Cases 3 and 4 are true twice (stuck ON).

#### Case 1

• | First gear is commanded.

• | The vehicle speed is greater than 11 km/h (7 mph).

• | The engine torque is 70-270 N·m (50-200 lb ft).

• | The throttle position is greater than 8%.

• | The gear ratio indicates fourth gear (0.65:1-0.75:1).

• | Condition is met for 2 seconds.

#### Case 2

• | Second gear is commanded.

• | The vehicle speed is greater than 11 km/h (7 mph).

• | The engine torque is 70-270 N·m (50-200 lb ft).

• | The throttle position is greater than 8%.

• | The gear ratio indicates third gear (0.95:1-1.05:1).

• | Condition is met for 1 second.

#### Case 3

• | Third gear is commanded.

• | The vehicle speed is greater than 11 km/h (7 mph).

• | The engine torque is 70-270 N·m (50-200 lb ft).

• | The throttle position is greater than 8%.

• | The gear ratio indicates second gear (1.52:1 to 1.62:1).

• | Condition is met for 3 seconds.

#### Case 4

• | Fourth gear is commanded.

• | The vehicle speed is 56-132 km/h (35-82 mph).

• | The engine torque is 0-105 N·m (0-80 lb ft).

• | The engine speed is less than 6700 RPM.

• | The throttle position is 7-40%.

• | The gear ratio is 1.05:1-2.97:1.

• | Condition is met for 3 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the Malfunction Indicator Lamp (MIL).

• | The PCM commands 3rd gear.

• | The PCM commands maximum line pressure.

• | The PCM inhibits Torque Converter Clutch.

• | The PCM disables shift adapts.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the MIL after three consecutive trips 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.

• | Ensure that the scan tool commanded gear has correct solenoid states and ratio. Refer to the Shift Solenoid Valve State and Gear Ratio table.

### Test Description

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

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

1. Set up data pairs on the Scan Tool . Drive the vehicle while commanding First gear with the Scan Tool .

2. This step verifies that the gear ratio indicates a Fourth gear start and the vehicle does not achieve First gear. The list of components should be inspected and repaired, if faulty.

3. This step verifies that the gear ratio indicates Third gear and the vehicle does not achieve Second gear. The list of components should be inspected and repaired, if faulty.

4. This step verifies that the gear ratio indicates Second gear and the vehicle does not achieve Third gear. The list components should be inspected and repaired, if faulty.

5. This step verifies that the gear ratio indicates First gear and the vehicle does not achieve Fourth gear. The list of components should be inspected and repaired, if faulty.

#### DTC P0756 2-3 Shift Solenoid Valve -- Performance

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls
2 | Have you performed the fluid checking procedure? | -- | Go to Step 3 | Go to Transmission Fluid Check
3 |

1. Install the Scan Tool .
2. With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the Scan Tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.

3. Record the DTC Freeze Frame and Failure Records, then clear the DTC(s).
4. Select A/T Outputs, Shift Trans.
5. Monitor the following data pairs:

• | Current gear

• | Gear ratio

6. Accelerate the vehicle and command First gear.

Is the gear ratio within the specified parameters?

0.65:1 to 0.75:1

Go to Step 4

Go to Step 5

4 |

1. Inspect for the following conditions:

• | A damaged Lo/Rev servo apply pin

• | A stuck 2-3 shift valve

• | Damaged or leaking oil seals (support seals)

• | The support stud from the case to the forward clutch is damaged or broken

• | The Lo roller clutch assembly is worn or damaged

• | The forward clutch piston is damaged or cracked

• | The forward clutch piston seals are rolled, cut or damaged

• | The forward sprag is damaged or not holding

• | Ball check valve #8 is missing

2. Repair or replace any malfunctioning components.

Refer to Transmission Overhaul in the 4T65-E Section of the Transmission Unit Repair Manual.

Is the inspection and repair complete?

--

Go to Step 11

--

5 | Accelerate the vehicle and command a 1-2 upshift. Is the gear ratio within the specified parameters? | 0.95:1 to 1.05:1 | Go to Step 6 | Go to Step 7
6 |

1. Inspect for the following conditions:

• | The 2nd clutch plates are burned or damaged

• | The 2nd clutch piston assembly is cracked or damaged

• | The 2nd clutch return spring and retainer assembly is broken or out of position

• | The 2nd clutch piston seals are rolled, damaged or leaking

• | The 2-3 shift valve is stuck

2. Repair or replace any malfunctioning components.

Refer to Transmission Overhaul in the 4T65-E Section of the Transmission Unit Repair Manual.

Is the inspection and repair complete?

--

Go to Step 11

--

7 | Accelerate the vehicle and command a 2-3 upshift. Is the gear ratio within the specified parameters? | 1.52:1 to 1.62:1 | Go to Step 8 | Go to Step 9
8 |

1. Inspect for the following conditions

• | The 3-4 shift valve bore plug is misassembled

• | The exhaust valve cup plug or the exhaust valve is improperly installed on the driven sprocket support

• | The 3rd clutch plates are burned or the splines are damaged

• | The 3rd clutch piston is cracked or damaged, or the ball check valve is damaged

• | The 3rd clutch seals on piston are cut or rolled

• | The ball check valves (437) are missing or stuck

• | Debris in the 2-3 Shift Solenoid Valve

2. Repair or replace any malfunctioning components.

Refer to Transmission Overhaul in the 4T65-E Section of the Transmission Unit Repair Manual.

Is the inspection and repair complete?

--

Go to Step 11

--

9 | Accelerate the vehicle and command a 3-4 upshift. Is the gear ratio within the specified parameters? | 2.87:1 to 2.97:1 | Go to Step 10 | Go to Diagnostic Aids
10 | Inspect and repair the following items:

• | Debris in the 2-3 Shift Solenoid Valve

• | The forward band is burned, slipping or missing

• | The forward servo pin is broken or seized

• | The forward servo cover seal is rolled, cut or damaged

• | The forward servo piston seal is rolled, cut or damaged

• | The forward servo cover is cracked

• | The 3-4 shift valve bore plug is misassembled

Refer to Transmission Overhaul in the 4T65-E Section of the Transmission Unit Repair Manual.

Is the inspection and repair complete?

--

Go to Step 11

--

11 | In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear Info, then clear the DTC(s).
3. Operate the vehicle under the following conditions:

• | The transmission fluid temperature is greater than 20°C (68°F).

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

• | The engine is not in fuel shut off.

• | The throttle position is greater than 8%.

• | The gear range is D4, D3, D2 or D1.

• | The vehicle speed is more than 11 km/h (7 mph).

• | The engine torque is 70-270 N·m(50-200 lb ft).

• | Each of the following pass criteria must be true for 2 seconds.

#### Case 1

- | Command 1st gear.

- | The gear ratio is 2.87:1 to 2.97:1.

#### Case 2

- | Command 2nd gear.

- | The gear ratio is 1.52:1 to 1.62:1.

#### Case 3

- | Command 3rd gear.

- | The gear ratio is 0.95:1 to 1.05:1.

#### Case 4

- | Command 4th gear.

- | The gear ratio is 0.65:1 to 0.75:1.

4. Select Specific DTC.
5. Enter DTC P0756.

Has the test run and passed?

--

System OK

Go to Step 1