P0446

Schematic:

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-A 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 and Poor Connections in Diagrams.

Refer to Intermittent Conditions for the Intermittents.

TEST DESCRIPTION

Steps 1 - 11:

Steps 12 - 20:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the valve operates. Repeat the commands as necessary.
3. 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).
18. .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.