GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2003 🢒 Montana - 4WD 🢒 DTC 🢒 DTC P0443

Circuit Description

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge valve. The EVAP canister purge valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

Conditions for Running the DTC
    • The engine speed is more than 400 RPM.
    • The system voltage is between 6-18 volts.

Conditions for Setting the DTC
    • The control module detects that the commanded state of the driver and the actual state of the control circuit Do NOT match.
    • The above conditions are present for a minimum of 5 seconds.

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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests if the concern is active. The EVAP purge solenoid is pulse width modulated (PWM). Clicking should be heard or felt when the purge solenoid is commanded to 50 percent and should stop when the EVAP purge solenoid is commanded to 0 percent. The rate at which the valve cycles should increase as the commanded state is increased and decreased as the commanded state is decreased. Repeat the commands as necessary.

    2.

  2. This step tests if a ground is constantly being applied to the EVAP purge solenoid.

    3.

  3. This step verifies that the control module is providing ground to the EVAP purge solenoid.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. Command the EVAP purge solenoid to 50 percent and then to 0 percent with a scan tool,

Do you hear or feel a clicking from the EVAP purge solenoid when the solenoid is commanded to 50 percent?

Go to Step 3

Go to Step 4

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30  seconds.
  3. Turn ON the ignition, with the engine OFF.
  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 4

Go to Intermittent Conditions

4
  1. Turn OFF the ignition.
  2. Disconnect the EVAP purge solenoid.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the EVAP purge solenoid with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

Go to Step 5

Go to Step 11

5

  1. Connect a test lamp between the control circuit of the EVAP purge solenoid and the ignition 1 voltage circuit of the EVAP purge solenoid.
  2. Command the EVAP purge solenoid to 0 percent with a scan tool.

Does the test lamp illuminate?

Go to Step 8

Go to Step 6

6

Command the EVAP purge solenoid to 50 percent with a scan tool.

Does the test lamp illuminate or pulse when the EVAP purge solenoid is commanded to 50 percent?

Go to Step 9

Go to Step 7

7

Test the control circuit of the EVAP purge solenoid for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 10

8

Test the control circuit of the EVAP purge solenoid for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

9

Test for an intermittent and for a poor connection at the EVAP purge solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

10

Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

11

Repair the open or short to ground in the ignition 1 voltage circuit of the EVAP purge solenoid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

12

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

Did you complete the replacement?

Go to Step 14

--

13

Replace the control module. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 14

--

14
  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 15

15

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