GM Service Manual Online
For 1990-2009 cars only

Circuit Description

If a control module is installed without being programmed, DTC P0602 will be set. During reprogramming and immediately after completion, DTC P0602 will also be set. This DTC should be successfully cleared after following the reprogramming procedures.

Since this diagnostic pertains to an internal VCM diagnostic check, no wiring schematic is required.

Conditions for Running the DTC

The ignition switch is in the Run position.

Conditions for Setting the DTC

No software data is present in the vehicle control module (VCM).

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
    • The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.

Conditions for Clearing the MIL or DTC

    • The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
    • Use a scan tool in order to clear the DTCs.

Test Description

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

  1. If the flashing procedure fails, verify that the equipment being used is functioning properly and that all the cable connections are clean and tight. Also, make sure that the software you download is correct for the VCM being flashed. If everything checks out OK and a second attempt fails, the VCM is damaged.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Flash the VCM with the correct software. Refer to VCM Replacement/Programming .

Does DTC P0602 reset?

--

Go to Step 3

Go to Step 5

3

  1. Verify that the equipment being used is functioning properly and that all the cable connections are clean and tight.
  2. Attempt to flash the VCM again.

Does DTC P0602 reset?

--

Go to Step 4

Go to Step 5

4

Important: The replacement VCM must be programmed.

Replace the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 5

--

5

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches a normal operating temperature.
  4. Select the DTC and the specific DTC functions.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the Conditions for Setting the DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 6

Go to Step 2

6

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK