For 1990-2009 cars
Engine Controls Components
EVAP Tank, Purge and Intake Plenum, Resonance Solenoid Valves
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

The evaporative emission (EVAP) vent valve is supplied switched battery power via the engine controls power relay. The engine control module (ECM) controls the valve by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.

### Conditions for Running the DTC

• | The ignition voltage is between 7.5 volts and 15.0 volts.

• | The engine speed is more than 40 RPM.

### Conditions for Setting the DTC

A short to ground, an open circuit, or a short to battery voltage is detected on the control circuit.

### Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

### Conditions for Clearing the MIL/DTC

• | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.

• | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

• | Use the J 35616 connector test adapter kit for any test that requires probing the ECM harness connector or a component harness connector.

• | If an intermittent circuit problem is suspected, check for a damaged harness. Inspect the wiring harness thoroughly. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help locate the fault. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Refer to Intermittent Conditions for the Intermittents.

### Test Description

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

1. Listen for an audible click when the valve operates. Repeat the commands as necessary.

2. This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm the coil may open, the amps drop to 0, or short, go to above 0.75 amp).

3. If no trouble is found in the control circuit or the connection at the ECM, the ECM may be damaged, however, this is an extremely unlikely failure.

#### DTC P0446 EVAP Vent Valve Control Circuit

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition, with the engine OFF.
2. Using the scan tool, command the vent (tank solenoid) valve ON and OFF.

Does the valve turn ON and OFF with each command?

--

Go to Step 3

Go to Step 5

3 |

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Jumper the Engine Controls Power Relay control circuit to ground.
4. Turn ON the ignition, with the engine OFF.
5. With the DMM on 10 amp scale, measure the current from the valve control circuit in the ECM harness connector to ground for 2 minutes .

Does the current draw measure within the range shown?

100 to 750 mA

Go to Diagnostic Aids

Go to Step 4

4 |

1. Turn OFF the ignition.
2. Disconnect the valve.
3. Using a DMM, measure the resistance from the valve control circuit in the ECM harness connector to ground.

The DMM should display an infinite resistance.

Does the DMM display an infinite resistance?

--

Go to Step 11

Go to Step 12

5 |

1. Turn OFF the ignition.
2. Disconnect the valve electrical connector.
3. Connect the test lamp between the terminals in the harness connector.
4. Turn ON the ignition.
5. Command the valve ON and OFF with the scan tool.

Does the test lamp turn ON and OFF with each command?

--

Go to Step 11

Go to Step 6

6 | Is the test lamp continuously illuminated? | -- | Go to Step 8 | Go to Step 7
7 | Probe the Switched B+ circuit in the valve harness connector with the test lamp connected to ground. The test lamp should illuminate. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 15
8 |

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Connect the test lamp between battery positive and the valve control circuit terminal.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 17

9 | Connect the test lamp between ground and the valve control circuit terminal. The test lamp should not illuminate. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 10
10 |

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Test the valve control circuit for continuity.

Does the DMM indicate circuit continuity?

--

Go to Step 17

Go to Step 13

11 | Check connections at the EVAP tank solenoid (vent) valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct a problem? | -- | Go to Step 19 | Go to Step 16
12 | Repair the shorted to ground EVAP tank solenoid control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 19 | --
13 | Repair the open EVAP tank solenoid control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 19 | --
14 | Repair the EVAP tank solenoid control circuit shorted to B+. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 19 | --
15 | Repair the open Switched B+ circuit to the EVAP tank solenoid valve. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 19 | --
16 | Replace the EVAP tank solenoid (vent) valve. Refer to Evaporative Emission Vent Valve Replacement . Is the action complete? | -- | Go to Step 19 | --
17 | Test for a poor connection or poor terminal tension at the ECM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct a problem? | -- | Go to Step 19 | Go to Step 18
18 | Important:

• | Perform the Idle Learn Procedure when replacing the ECM.

• | This vehicle is equipped with a Theft Deterrent System that interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 19

--

19 |

1. Using the scan tool, clear the DTCs.
2. Start the engine.
3. Allow the engine to idle until the engine reaches the 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 Running this DTC until the scan tool indicates that the diagnostic Ran.

Does the scan tool indicate that the diagnostic Passed?

--

Go to Step 20

Go to Step 2

20 | Does the scan tool display any additional, undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK