GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Tahoe - 4WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P1441

Circuit Description

The powertrain control module (PCM) monitors the amount of vacuum pressure in the evaporative emissions (EVAP) system by monitoring the fuel tank pressure (FTP) sensor signal. The PCM seals the EVAP system by commanding the EVAP purge solenoid OFF and the EVAP vent valve ON. The PCM monitors the fuel tank pressure sensor in order to determine if the EVAP purge solenoid is leaking vacuum to the EVAP system. This diagnostic trouble code (DTC) sets if the vacuum in the EVAP system is more than a predetermined value within a predetermined time.

Conditions for Running the DTC

    • DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1111, P1112, P1114, P1115, P1121 or P1122 are not set.
    • No active system voltage DTCs
    • The ignition voltage is between 10-18 volts.
    • The barometric pressure (BARO) is more than 75 kPa.
    • The fuel level is between 15-85 percent of full capacity.
    • The engine coolant temperature is between 4-30°C (39-86°F).
    • The intake air temperature is between 4-30°C (39-86°F).
    • The start up engine coolant and intake air temperatures are within 8°C (14°F) of each other.
    • The throttle position (TP) angle is between 0-99.6 percent.

Conditions for Setting the DTC

The EVAP system develops a vacuum more than a predetermined value when purge is not commanded.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (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.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Before replacing any components, visually and physically check for the following:

    • Mis-routed harness
    • Rubbed through wire insulation
    • Broken wire inside the insulation
    • Kinked or damaged vacuum hoses
    • Physically damaged system components
    • Inspect components and vacuum lines for traces of carbon or other contaminants. The presence of foreign material may be causing a restriction in the system or preventing the solenoid valve from closing properly. Either condition may cause a DTC to set.

For an intermittent condition, refer to Symptoms - Engine Controls .

Test Description

The number below refer to the steps number on the Diagnostic Table.

  1. This step checks for a EVAP purge solenoid valve that is leaking vacuum to the EVAP system when EVAP system purge is not commanded by the PCM.

    Check for possible carbon contamination of the EVAP purge solenoid valve and the purge line.

Step

Action

Yes

No

Schematic Reference: Emission Hose Routing Diagram and Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Install a scan tool.
  2. Disconnect the EVAP purge line from the EVAP purge solenoid valve.
  3. Connect a vacuum gauge (in Hg) to the solenoid purge port.
  4. Idle the engine.
  5. Command the EVAP purge solenoid valve OFF with a scan tool.

Does the vacuum gauge indicate a vacuum?

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.

    2. Important: Check for carbon contamination. Refer to Evaporative Emission System Cleaning .

  2. Replace the EVAP purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Is the action complete?

Go to Step 4

--

4
  1. Use the scan tool in order to clear the DTCs.
  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 5

Go to Step 2

5

With a scan tool, observe the stored information, Capture Info.

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

Go to Diagnostic Trouble Code (DTC) List

System OK