GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 Envoy - 2WD 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610

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. The following DTCs are diagnosed in this DTC table:

    • DTC P0601
    • DTC P0602
    • DTC P0604
    • DTC P0606
    • DTC P0607
    • DTC P1621
    • DTC P1680
    • DTC P1681

Diagnostic Aids

For complete details on programming the PCM, refer to Service Programming System (SPS) Description .

Test Description

The numbers below refer to the step numbers 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-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Is DTC P0602 set?

Go to Step 3

Go to Step 5

3

Program the PCM. Refer to Powertrain Control Module Programming .

Does DTC P0602 reset?

Go to Step 4

Go to Step 6

4
  1. Ensure that all tool connections are secure.
  2. Ensure the programming equipment is operating correctly.
  3. Ensure the correct software and the correct calibration is used.
  4. Attempt to program the PCM. Refer to Powertrain Control Module Programming .

Does DTC P0602 reset?

Go to Step 5

Go to Step 6

5

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 6

--

6
  1. Turn ON the ignition, with the engine OFF.
  2. Use a scan tool in order to clear DTCs.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.

Does the scan tool display any DTCs?

Go to Diagnostic Trouble Code (DTC) List

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

System OK