GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Epica 🢒 DTC 🢒 DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610

Circuit Description

This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM).

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0601 Control Module Read Only Memory (ROM)
    • DTC P0604 Control Module Random Access Memory (RAM)
    • DTC P0605 Control Module Programming Read Only Memory (ROM)

Conditions for Running the DTC

DTC P0601

    • The ignition is ON, with the engine OFF or the engine is operating.
    • DTC P0601 runs once an ignition cycle.

DTC P0604

    • The ignition is ON, with the engine OFF or the engine is operating.
    • DTC P0604 runs once an ignition cycle.

DTC P0605

    • The ignition is ON, with the engine OFF or the engine is operating.
    • DTC P0605 runs once an ignition cycle.

Conditions for Setting DTC

DTC P0601

The ECM detects that the checksum calculation does not match the expected checksum.

DTC P0604

The ECM detects an internal condition for more than 3 seconds.

DTC P0605

The ECM detects an internal condition for more than 3 seconds.

Action Taken When the DTC Sets
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC
    • 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 non-emission related diagnostic.
    • Clear the DTC with a scan tool.

DTC P0601, P0604, or P0605

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

Replace the engine control module (ECM). Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 3

--

3

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 4

4

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