P0412

CIRCUIT DESCRIPTION
Ignition voltage is supplied directly to the Secondary Air Injection (AIR) vacuum control solenoid. The Powertrain Control Module (PCM) 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 that is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the PCM 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.

The PCM will monitor the control circuit for the following:
^ A short to ground
^ A short to voltage
^ An open circuit
^ An open solenoid
^ An internally shorted or excessively low resistance solenoid

When the PCM detects any of the above malfunctions, this DTC will set and the affected driver will be disabled.

CONDITIONS FOR RUNNING THE DTC
^ The ignition voltage is between 9-18 volts.
^ The engine speed is more than 80 RPM.
^ The PCM driver transitions from ON to OFF or from OFF to ON.

CONDITIONS FOR SETTING THE DTC
^ A short to ground, an open circuit, or a short to battery voltage is detected on the control circuit.
^ The condition is present for at least 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

DIAGNOSTIC AIDS

NOTE: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:
^ The PCM harness connectors
^ The electrical center fuse/relay cavities
^ The component terminals
^ The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

NOTE: Do not operate the AIR pump for more than 60 seconds. Continuous operation of the AIR pump in excess of 60 seconds will damage the AIR pump. If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions

An AIR pump that had become inoperative and had shown indications of having exhaust gases in the outlet port would indicate check valve failure.

TEST DESCRIPTION

Steps 1-13:

The numbers below refer to the step numbers on the diagnostic table.
1. The Diagnostic System Check-Computer and Control Systems prompts you to complete some basic checks and store the Freeze Frame/Failure Records on the scan tool.
2. Listen for an audible click when the solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the feed side of the solenoid.
4. Verifies that the PCM is providing ground to the solenoid.
5. Tests if ground is constantly being applied to the solenoid.
12. The PCM utilizes Electrically Erasable Programmable Read Only Memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.