GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Engine 🢒 Engine Controls and Fuel - 7.8L (LG4) 🢒 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 control module. This diagnostic also addresses if the control module is not programmed. The following diagnostic trouble codes (DTCs) are diagnosed in this DTC table:

Important: The DTCs listed below, are not applicable to all vehicles.

    • DTC P0602 Control Module Not Programmed
    • DTC P0606 ECM Processor Fault
    • DTC P1621 Control Module Long Term Memory Performance

Test Description

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

  1. A DTC P0602 indicates the engine control module (ECM) 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 engine control module (ECM). Refer to Engine Control Module Replacement/Restore Fuel Rate Data .

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 ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data .

Does DTC P0602 reset?

Go to Step 5

Go to Step 6

5

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

Did you complete the replacement?

Go to Step 6

--

6
  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 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

System OK