GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Restraints 🢒 SIR 🢒 DTC P0756

Object Number: 40582 Size: SF
Master Electrical Component List
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

Circuit Description

The 2-3 shift solenoid (SS) valve is a normally-open exhaust valve that, in conjunction with the 1-2 shift solenoid (SS) valve, allows four different shifting combinations. Refer to Shift Solenoid Valve State and Gear Ratio . The 2-3 SS valve is attached to the control valve body within the transmission.

The transmission control module (TCM) monitors the actual gear ratio, and compares the actual gear ratio with the commanded gear ratio. DTC P0756 sets under two conditions:

    • A stuck ON 2-3 SS valve
    • A stuck ON 2-3 shift valve

When the TCM detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 is a type A DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0756 2-3 Shift Solenoid Valve Performance - No First or Second Gear

Conditions for Running the DTC
    • No MAP DTCs P0107 or P0108.
    • No TP DTCs P0120 or P0220.
    • No ISS DTCs P0716 or P0717.
    • No OSS DTCs P0722 or P0723.
    • No TCC stuck ON DTC P0742.
    • No 1-2 SS electrical DTCs P0973 or P0974.
    • No 2-3 SS electrical DTCs P0976 or P0977.
    • The engine is running for 5 seconds.
    • The transmission fluid temperature (TFT) is 20°C to 130°C (68°F to 266°F).
    • The throttle position (TP) is 8 percent or more.
    • The input speed is 150-6,000 RPM.
    • The output speed is 200 RPM or more.
    • The engine torque is greater than 50 N·m (37 lb ft).
    • The TCC slip speed is greater than -20 RPM when 1st gear is commanded.
    • The time since the last gear change is 0.30 seconds.

Conditions for Setting the DTC
    • The TCM commands 1st gear and the gear ratio is 0.65:1-1.87:1, 4th gear, for 2 seconds.
    • The TCM commands 2nd gear and the gear ratio is 0.95:1-1.05:1, 3rd gear, for 1 second.

Action Taken When the DTC Sets
    • The TCM illuminates the malfunction indicator lamp (MIL).
    • The TCM inhibits 1st gear.
    • The TCM commands maximum line pressure.
    • The TCM freezes transmission adaptive functions.
    • The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
    • The TCM stores DTC P0756 in TCM history.

Conditions for Clearing the MIL/DTC
    • The TCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
    • A scan tool can clear the MIL/DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Diagnostic Aids
    • If you clear DTC P0756, and then cannot set DTC P0756 again, inspect for the following conditions:
       - Fluid contamination
       - Plugged fluid circuits
       - Restricted fluid circuits
    • Refer to Shift Solenoid Valve State and Gear Ratio .

Test Description

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

  1. This step verifies a 4-3-3-4 shift pattern.

    2.

  2. This step tests for a mechanical or hydraulic condition causing the 2-3 SS valve to be stuck ON, or the circuit to be applied.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Did you perform the Transmission Fluid Checking Procedure?

--

Go to Step 3

Go to Transmission Fluid Check

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the TCM.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Use the scan tool snapshot mode in order to record current gear and gear ratio.
  6. Drive the vehicle in D4, in order to obtain 1-2, 2-3 and 3-4 shifts with a TP greater than 8%.

Are current gear and gear ratio within the specified values?

1st/4th:

0.65:1-1.87:1

2nd/3rd:

0.95:1-1.05:1

Go to Step 4

Go to Diagnostic Aids

4

  1. Inspect the 2-3 shift circuit for the following conditions:
    2. • 2-3 SS valve mechanically stuck ON
    • 2-3 shift valve stuck in the applied position
    • Refer to Shift Solenoid Leak Test .
  2. Repair the circuit as necessary.

Refer to 2-3 Shift Solenoid Valve Replacement .

Did you complete the repair?

--

Go to Step 5

--

5

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Drive the vehicle in D4.
    • Allow the transmission to shift through all the gears.
    • Monitor the current gear and gear ratios. The actual gear ratios must match the commanded gears for 0.9 seconds, for all gears.
  4. Select Specific DTC.
  5. Enter DTC P0756.

Has the test run and passed?

--

Go to Step 6

Go to Step 2

6

With the scan tool, observe the stored information, capture info and DTC info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK