GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The torque converter clutch (TCC) solenoid is located in the control valve body of the transmission. The powertrain control module (PCM) commands the TCC solenoid by turning the solenoid ON or OFF, enabling the TCC to engage and disengage when specific signals are received by the PCM.

Shifting of O/D is performed by the PCM controlling the ON and OFF switching functions of the TCC solenoid. If an open occurs in any of the solenoid valves, the PCM controls the remaining functioning shift solenoid valves to allow the vehicle to be operated smoothly in a fail safe mode.

When the PCM detects a continuous open in the TCC solenoid valve circuit, then DTC P2770 sets.

DTC P2770 is a type B DTC.

Conditions for Running the DTC

PCM detects an open in the TCC solenoid circuit 4 times (2 trip detection logic).

Conditions for Setting the DTC

DTC P2770 sets when the following condition occurs:

The PCM detects an open in the TCC solenoid circuit when the solenoid is commanded ON or OFF.

Action Taken When the DTC Sets

    • At the time of the failure, the PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as a Failure Record.
    • The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive drive trip in which the Conditions for Setting the DTC are met.
    • The PCM stores DTC P2770 in PCM history.

Conditions for Clearing the MIL/DTC

    • 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.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Listen for an audible click when the solenoid energizes.

Step

Action

Value(s)

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

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 PCM Freeze Frame Failure Records. Using the Clear Info function erases the Freeze Frame Failure Records from the powertrain control module (PCM).
       • Using the Clear Info function erases stored DTCs in the PCM.

  4. Record the DTC Freeze Frame and Failure Records.
  5. Clear the DTC.
  6. Use the scan tool in order to command the torque converter clutch (TCC) solenoid ON.

Does the solenoid operate?

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Go to Step 5

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Test the circuit from the PCM to the TCC solenoid for an open circuit. Refer to Testing for Short to Ground in Wiring Systems.

Did you find a condition?

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Go to Step 6

Go to Step 5

4

  1. Remove the transmission oil pan.
  2. Test the shift solenoid wiring from the 10-way connector to the shift solenoid connector for the following conditions:

An open circuit--Refer to Testing for Short to Ground in Wiring Systems.

Did you find a condition?

--

Go to Step 7

Go to Step 8

5

Replace the PCM. Refer to Powertrain Control Module Programming and Setup in Programming and Setup.

Is the action complete?

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Go to Step 9

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6

Perform the necessary wiring repairs. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

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Go to Step 9

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7

Replace the internal transmission wiring harness. Refer to Solenoids and Wiring Harness Replacement .

Is the action complete?

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Go to Step 9

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8

Replace the TCC solenoid valve. Refer to Solenoids and Wiring Harness Replacement .

Is the action complete?

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Go to Step 9

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9

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Turn ON the ignition, with the engine OFF.
  4. Select Specific DTC.
  5. Enter DTC P2770.

Has the test run and passed?

--

Go to Step 10

Go to Step 2

10

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?

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

System OK