P0412

AIR SOLENOID VALVE CONTROL SOLENOID

Diagram Chart:

Electrical:

CIRCUIT DESCRIPTION
The purpose of the Secondary Air Injection (AIR) system is to reduce the Hydrocarbon (HC), the Carbon Monoxide (CO), and the Oxides of Nitrogen (NOx) exhaust emissions by causing any combustible gases in the exhaust to re-burn. This also causes the catalytic converters and the heated oxygen sensors to reach the normal operating temperatures more quickly, thus the Closed Loop operation occurs earlier.

When the engine is started, the ECM commands the AIR pump relay and the AIR Cutoff Valve Vacuum Control solenoid on, injecting clean air into the engine exhaust ports. The ECM switches the AIR system off when the oxygen sensors become active. The AIR Cutoff Valve prevents air from being drawn into the system when the AIR pump is off. The vacuum to the valve is controlled by the AIR Cutoff Valve Vacuum Control solenoid. A check valve close to the engine prevents hot exhaust gases from backing up into the AIR system.

The AIR Cutoff Valve Vacuum Control solenoid is supplied power via the Engine Controls Power Relay (Switched B+). The Engine Control Module (ECM) controls the solenoid 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
Tested continuously

CONDITIONS FOR SETTING THE DTC
A short to ground, an open circuit, or a short to battery voltage 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 does not fail.
^ A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.
^ The ECM battery voltage is interrupted.
^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS
Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:
^ Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure.

^ Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc.

^ Damaged harness. Inspect the wiring harness for any damage. 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 in order to locate the fault.

Refer to Symptoms / Intermittents. Testing and Inspection

TEST DESCRIPTION
The number(s) below refer to the step numbers on the diagnostic table.

2. Listen for an audible click when the solenoid 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 (above 0.75 amp).

13. 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.