GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Savana (CNG) 🢒 DTC 🢒 DTC P0601

Circuit Description

The Alternative Fuels ECM contains data storage areas. The Alternative Fuels ECM runs a test on the stored data called a checksum. This DTC is used to indicate a failure has occurred within the Alternative Fuels ECM.

Conditions for Running the DTC

The ignition switch is ON.

Conditions for Setting the DTC

The Alternative Fuels ECM monitors an internal malfunction.

Action Taken When the DTC Sets

The Alternative Fuels ECM will switch-over to gasoline fuel operation. Alternative fuel operation will not be attempted until the next ignition key cycle.

    • The Alternative Fuels ECM will illuminate the MIL and store the DTC as History during 1 drive trip in which the diagnostic runs and fails.
    • The Alternative Fuels ECM will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

    • The Last Test Failed status will clear when the DTC runs and passes.
    • The Alternative Fuels ECM will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.
    • The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.
    • All DTC Information can be cleared with a scan tool.

Test Description

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

  1. Any failure of the Alternative Fuels ECM internal tests that results in this DTC being set requires that the Alternative Fuels ECM be replaced.

Step

Action

Yes

No

1

Did you perform the Alternative Fuels Engine Controls Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

2

  1. Replace the Alternative Fuels ECM. Refer to Alternative Fuels Engine Control Module Replacement .
  2. Program the replacement Control Module with the correct vehicle software and calibration.

Is the replacement complete?

Go to Step 3

--

3
  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number that 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?

System OK

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)