GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 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). This diagnostic also addresses if the ECM 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

Conditions for Running the DTC

DTC P0601

    • The ignition is ON.
    • This DTC runs continuously.

DTC P0602

This DTC runs continuously.

DTC P0604

    • The ignition is ON.
    • This DTC runs once per ignition cycle.

DTC P0606

    • The ignition is ON.
    • This DTC runs continuously.

Conditions for Setting the DTC

DTC P0601

The ECM detects read only memory (ROM) errors for more than 1 second.

DTC P0602

The ECM detects that programming is incomplete for more than 1 second.

DTC P0604

The ECM detects that random access memory (RAM) errors for more than 1 second.

DTC P0606

The ECM detects an internal condition for more than 1 second.

Actions Taken When the DTC Sets
    • 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.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the 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 numbers below refer to the step numbers on the diagnostic table.

  1. A DTC P0602 indicates the ECM is not programmed.

    2.

  2. Attempt to program the ECM. If the ECM fails to program a second time, replace the ECM.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 3

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the DTC information with a scan tool.

Does the scan tool display DTC P0686, P0687, P0689, or P0690?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

Is DTC P0606 set?

Go to Step 4

Go to Step 5

4

Was DTC P0606 only present after interrogating the vehicle for stored Failure Records or Freeze Frame Data with a scan tool?

Go to Step 9

Go to Step 8

5

Is DTC P0602 set?

Go to Step 6

Go to Step 8

6

Program the engine control module (ECM). Refer to Service Programming System (SPS) .

Does DTC P0602 reset?

Go to Step 7

Go to Step 9

7

  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 ECM. Refer to Service Programming System (SPS) .

Does DTC P0602 reset?

Go to Step 8

Go to Step 9

8

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

Did you complete the replacement?

Go to Step 9

--

9
  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 as specified in the supporting text.

Does the DTC run and pass?

Go to Step 10

Go to Step 3

10

Observe the Capture Info with a scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK