GM Service Manual Online
For 1990-2009 cars only

Description

This diagnostic applies to internal microprocessor integrity conditions within the powertrain control module (PCM). This diagnostic also addresses if the PCM is not programmed.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0601 Control Module Read Only Memory (ROM)
    • DTC P0602 Control Module Not Programmed
    • DTC P2610 Control Module Ignition Off Timer Performance

Conditions for Running the DTC

DTC P0601

The following conditions must be met:

    • The ignition switch is in Run or Crank.
    • System voltage is more than 5 volts.
    • The Engine Speed parameter is less than 5,000 RPM.

DTC P0602

The following conditions must be met:

    • The ignition switch is in Run or Crank.
    • The controller is identified as a service replacement PCM.

DTC P2610

The following conditions must be met:

    • The ignition switch is in the OFF position for at least 1.6 seconds.
    • Low battery voltage or a battery disconnect condition has not taken place. Ignition off time from the previous ignition cycle is stored.

Conditions for Setting the DTC

DTC P0601

The PCM checksum value is incorrect for at least one sample. Each sample is 50 milliseconds. The PCM detects that the checksum value is incorrect for 0.05 seconds. This diagnostic runs continuously.

DTC P0602

The PCM has not been programmed with Key ON and Engine OFF for one sample. Each sample is 100 milliseconds. The PCM has not been programmed at Key ON and Engine OFF for 0.1 seconds. This diagnostic runs continuously.

DTC P2610

This diagnostic has 2 tests that may set this DTC.

    • The PCM detects the ignition off timer is less than one second.
    • The ignition is in the OFF position for more than 8 seconds and the ignition off timer has not transitioned to Enable and/or the sample counter has not incremented.
    • This diagnostic runs continuous.

Action Taken When the DTC Sets

DTCs P0601 and P0602

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

DTC P2610

    • The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
    • If the diagnostic reports a failure, the control module uses a cold start model based on the engine coolant temperature and intake air temperature at engine start-up. Using the cold start model ensures that the control module is able to determine how much time has elapsed between ignition cycles.

Conditions for Clearing the MIL/DTC

DTCs P0601, P0602, and P2610

    • The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

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

  1. A DTC P0602 indicates the PCM is not programmed.

Step

Action

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

Is DTC P0602 set?

Go to Step 3

Go to Step 5

3

Program the powertrain control module (PCM). Refer to Service Programming System (SPS) in Programming and Setup.

Does DTC P0602 reset?

Go to Step 4

Go to Step 6

4

  1. Ensure that all tool connections are secure.
  2. Ensure that the programming equipment is operating correctly.
  3. Ensure that the correct software/calibration package is used.
  4. Attempt to program the PCM. Refer to Service Programming System (SPS) in Programming and Setup.

Does DTC P0602 reset?

Go to Step 5

Go to Step 6

5

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 6

--

6

Start the engine.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 7

7

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

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

System OK