GM Service Manual Online
For 1990-2009 cars only

Description

The DTC P0606 Control Module Internal Performance sets when the powertrain control module (PCM) has determined that the control module has an internal fault. The PCM performs continuous self checks of all internal circuits. There are two central processing units (CPU) within the control module. If the outputs from the two CPUs deviates from the standard level, a DTC P0606 sets.

Condition for Running the DTC

    • The ignition is ON.
    • DTC P0606 runs continuously once the above condition is met.

Conditions for Setting the DTC

DTC P0606 sets when an internal PCM error is detected.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

    • The MIL turns OFF after 3 consecutively passing trips without a fault present.
    • A history DTC clears after 40 consecutive warm-up cycles without a fault.
    • Perform the scan tool Clear DTC Information function.

Diagnostic Aids

Check the PCM for water contamination. Water entering the PCM can cause damage and corrosion to the circuit boards and to internal components. Repair the source of the water entry before the installation of a replacement PCM.

A DTC P0606 can set if an incorrect PCM is installed in the vehicle. Install the correct PCM according to the vehicle and/or the engine type and equipment options.

Test Description

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

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step determines if the fault is present. Replace the PCM if DTC P0606 sets again.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: If the vehicle does not start, crank the engine in order to allow the DTC to set.

  1. Install a scan tool.
  2. Clear the scan tool information.
  3. Turn OFF the ignition, in order to initialize the powertrain control module (PCM).
  4. Turn ON the ignition.
  5. Wait 10 seconds and check for DTCs.

Does the scan tool indicate a DTC P0606?

Go to Step 3

Go to Diagnostic Aids

3

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 4

--

4

  1. Start the engine.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 5

Go to Step 2

5

With a scan tool, observe the stored information, Capture Info.

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

Go to Diagnostic Trouble Code (DTC) List

System OK