GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC P0756

Circuit Description

The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves. The 2-3 SS valve is a normally-open exhaust valve that is used with the 1-2 SS valve in order to allow 4 different shifting combinations.

When the powertrain control module (PCM) detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 is a type A DTC.

Conditions for Running the DTC
    • No throttle position (TP) sensor DTCs P0122 or P0123.
    • No vehicle speed sensor (VSS) assembly DTCs P0502 or P0503.
    • No torque converter clutch (TCC) solenoid valve DTC P0740.
    • No TCC stuck ON DTC P0742.
    • No 1-2 SS valve DTC P0753.
    • No 2-3 SS valve DTC P0758.
    • No 3-2 SS valve assembly DTC P0785.
    • No transmission fluid pressure (TFP) manual valve position switch DTC P1810.
    • The engine speed is greater than 450 RPM for 5 seconds.
    • The engine is not in fuel cutoff.
    • The gear range is D4.
    • The TP angle is greater than 10 percent.
    • The transmission fluid temperature is 20-130°C (68-266°F).
    • The system voltage is 10-18 volts.
    • The engine torque is 67-542 N·m (50-400 lb ft).
    • The transmission output speed is 150 RPM or greater.

Conditions for Setting the DTC

DTC P0756 sets if the following conditions occur:

Condition 1

    • The PCM commands first gear for 2 seconds.
    • The estimated gear ratio is 0 to 1.4.
    • The TCC slip speed is -3,000 to 200 RPM.
    • All conditions are met for one second.

Condition 2

    • The PCM commands second gear for one second.
    • The estimated gear ratio is 0.9 to 1.2.
    • The torque converter efficiency is greater than 0.5.
    • All conditions are met for 2 seconds.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM commands 3rd gear only.
    • The PCM commands maximum line pressure.
    • The PCM inhibits TCC engagement.
    • The PCM inhibits fourth gear if the transmission is in hot mode.
    • The PCM freezes shift adapts from being updated.
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
    • The PCM stores DTC P0756 in PCM history.

Conditions for Clearing the MIL/DTC
    • The PCM 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 PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

Verify that the transmission meets the specifications in the Shift Speed table.

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.

  1. This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.

DTC P0756

Step

Action

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Powertrain Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 5.7L

2

  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 powertrain control module (PCM).

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Drive the vehicle in D4 range under the following conditions, accelerate the vehicle, ensuring that the PCM commands 1st, 2nd, 3rd, and 4th gears.

Did you detect a 4-3-3-4 shift pattern?

Go to Step 3

Go to Diagnostic Aids

3
  1. Inspect the shift solenoid/hydraulic circuit for the following conditions:
    2. • Debris or chips in the AFL oil passage
    • 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 .
  2. Clean and inspect the related valves, bores and the valve body for debris or contamination.

Did you find and correct the condition?

Go to Step 4

--

4

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Drive the vehicle in D4 range, hold the throttle at 40 percent and accelerate to 64 km/h (40 mph), only if traffic and road conditions permit.
  4. Select Specific DTC.
  5. Enter DTC P0756.

Has the test run and passed?

System OK

Go to Step 1