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 whether or not 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 P0604 Control Module Random Access Memory (RAM)
    • DTC P0606 Control Module Internal Performance
    • DTC P2610 Control Module Ignition Off Timer Performance

Conditions for Running the DTC

DTC P0601

    • The ignition switch is in the Run or Crank position.
    • DTC P0601 runs continuously when the above condition is met.

DTC P0602

    • The ignition switch is in the ON position.
    • DTC P0602 runs continuously when the above condition is met.

DTC P0604

    • The ignition switch is in the Run or Crank position.
    • DTC P0604 runs continuously when the above condition is met.

DTC P0606

    • The ignition switch is in the Run or Crank position, or the key is being turned OFF.
    • DTC P0606 runs continuously when the above condition is met.

DTC P2610

    • The PCM is powered down.
    • DTC P2610 runs once every time the key is turned OFF.

Conditions for Setting the DTC

The PCM detects an internal failure or an incomplete programming for more than 5 seconds.

Action Taken When DTCs P0601, P0602, and P0604 are Set

    • 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.

Action Taken When DTC P2610 is Set

    • The control module illuminates the malfunction indicator lamp (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.

Conditions for Clearing the MIL/DTCs P0601, P0602, P0604, and P2610

    • The control module turns OFF the malfunction indicator lamp (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 that 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

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) .

Does DTC P0602 reset?

Go to Step 4

Go to Step 7

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) .

Does DTC P0602 reset?

Go to Step 5

Go to Step 7

5

Test all voltage and ground inputs to the engine control module (ECM) for an open circuit or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 8

8

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

System OK