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For 1990-2009 cars only
Makes 🢒 Holden 🢒 2005 🢒 Commodore Acclaim 🢒 DTC 🢒 DTC P0751

DTC P0751 V6

DTC Description

This diagnostic procedure supports DTC P0751 1-2 shift Solenoid (SS) Valve Performance -- No First or Fourth Gear.

Circuit Description

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

If the transmission control module (TCM) detects a 2-2-3-3 shift pattern, then DTC P0751 sets. DTC P0751 is a type B DTC.

Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View, Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in diagnosis.

Conditions for Running the DTC

No DTCs P0722, P0723, P0742, P0894, P0973, P0974, P0976, P0977 or P1815.

    • Ignition voltage is 8-18 V.
    • The engine RPM. is 500-6,500 RPM for greater than 5 seconds.
    • The transmission fluid temperature is 20-130°C.
    • The throttle position is greater than 10 percent.
    • The input shaft speed is 200-6,800 RPM.
    • The output shaft speed is greater than 100 RPM.

Conditions for Setting the DTC

Both of the following conditions must occur twice during the same trip:

    • Fail Case 1: The TCM commands 1st gear and the resulting gear ratio is 1.44:1-1.50:1 for 2 seconds.
    • Fail Case 2: The TCM commands 4th gear and the resulting gear rations 0.98:1-1.03:1 for 4 seconds.

Action Taken When the DTC Sets
    • The TCM requests the ECM to illuminate the check powertrain icon during the second consecutive trip in which the Conditions for Setting the DTC are met.
    • The TCM commands maximum line pressure.
    • The TCM freezes transmission adaptive functions.
    • At the time of the first failure, the TCM records the operating conditions when the conditions for setting the DTC are met. The TCM stores this information as a Failure Record.
    • At the time of the second failure, the ECM records the operating conditions when the conditions for setting the DTC are met. The ECM stores this information as a Freeze Frame.
    • The TCM stores DTC P0751 in TCM history during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the DTC
    • The ECM turns off the check powertrain icon after the fourth consecutive drive trip in which the TCM does not send a check powertrain icon illumination request.
    • Tech 2 can clear the DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the ignition is off long enough in order to power down the TCM.

Diagnostic Aids
    • If you clear DTC P0751, and then cannot reset DTC P0751, the following conditions may exist:
       - Fluid contamination
       - Block fluid circuits
       - Restricted fluid circuits
    • Refer to Shift Solenoid Valve State and Gear Ratio.

Test Description

The following numbers refer to the step numbers in the diagnostic table:

2 This step tests the TCM commanded all shifts, all shift solenoid valves responded correctly, and if all the shifts did not occur.

3 Checks the mechanical components that cause the DTC and their state.

Step

Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2
  1. Connect Tech 2 to the DLC.
  2. Turn on the ignition, with the engine off.

    3. Important: Before clearing the DTC, use the Tech 2 Freeze Frame/Failure Record in order to record the transmission parameters at the time the DTC set. Using Tech 2 to clear the DTC(s) erases the Freeze Frame/Failure Record records from the TCM.

  3. On Tech 2 select:

    4. Transmission / Automatic Transmission / Diagnostic Trouble Codes / Freeze Frame

  4. Select the relevant DTC and note the parameters at the time of the DTC setting.
  5. On Tech 2 select:

    6. Diagnostic Trouble Codes / Clear Engine and Transmission DTCs.

  6. Follow the instructions on Tech 2 and clear the DTCs.
  7. Drive the vehicle in D4 range under the following conditions:
    8. • Accelerate the vehicle
    • Ensure the TCM commands 1st, 2nd, 3rd, and 4th gears.

Did you detect a 2-2-3-3 shift pattern?

Go to Step 3

Refer to Diagnostic Aids within this Section

3

Inspect the shift solenoid/hydraulic circuit for the following conditions:

    • An internal malfunction
    • Damage seals on the shift solenoid valve. Perform the shift solenoid leak test, refer to Shift Solenoid Leak Test.

Did you find and correct the condition?

Go to Step 4

--

4

Perform the following procedure in order to verify the repair:

  1. On Tech 2 select:

    2. Diagnostic Trouble Codes / Clear Engine and Transmission DTCs

  2. Follow the instructions on Tech 2 and clear any DTCs.
  3. Drive the vehicle in D4 range under the following conditions, only if traffic and road conditions permit:
    4. • Hold the throttle at 20%, and
    • Accelerate to 88 km/h.
  4. On Tech 2 select:

    5. Diagnostic Trouble Codes / Read DTC Information.

Has DTC P0751 set?

Go to Step 2

Go to Step 5

5

On Tech 2 select:

Diagnostic Trouble Codes / Read DTC Information

Does Tech 2 display any DTCs you have not diagnosed?

Refer to Diagnostic Trouble Code (DTC) List/Type

System OK

When all diagnosis and repairs are completed, check the system for correct operation