P0412

DTC P0412

DTC DESCRIPTOR

DTC P0412
Secondary Air Injection (AIR) Solenoid Control Circuit

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

AIR Pressure Sensor:

CIRCUIT/SYSTEM DESCRIPTION
The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the secondary AIR injection pump, provides filtered air on demand to the AIR control solenoid valve/pressure sensor assembly. The AIR control solenoid valve/pressure sensor assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR valve relay supplies the current needed to operate the AIR control solenoid valve/pressure sensor assembly. A pressure sensor is used to monitor the air flow from the AIR pump. The control module supplies the internal pressure sensor with a 5-volt reference, an electrical ground, and a signal circuit.

The AIR diagnostic uses 3 phases to test the AIR system:
1. DTCs P0411 and P2430 run during Phase 1
2. DTCs P2430 and P2440 run during Phase 2
3. DTC P2444 runs during Phase 3

In all 3 phases, testing is accomplished by comparing the measured pressure against the expected pressure. The control module can detect faults in the AIR pump, AIR control solenoid valve/pressure sensor assembly, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing.

CONDITIONS FOR RUNNING THE DTC
- The system voltage is between 9-18 volts.
- This DTC runs on a 100 ms loop.
- DTC P0412 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The actual and expected states of the AIR Solenoid Relay Control Circuit do not match.
- The condition exists for at least 2 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.

CIRCUIT/SYSTEM VERIFICATION
With the ignition ON and the engine OFF, enable and disable the AIR solenoid with a scan tool while observing that the solenoid relay operates.
- If the solenoid relay does not operate then proceed with Circuit/System Testing.

CIRCUIT/SYSTEM TESTING
1. With the ignition ON, the engine OFF, and the solenoid enabled with a scan tool, observe the relay and the solenoid while manipulating all related wiring and connectors.
- If manipulation does affect the relay or the solenoid then repair the harness or connector.
2. With the ignition ON, the engine OFF, and the solenoid relay removed, connect a test lamp from the relay coil voltage supply circuit to ground and observe that the lamp illuminates.
- If the lamp does not illuminate then test the voltage supply circuit for high resistance or a short to ground.
3. With the ignition ON, the engine OFF, and the solenoid relay removed, connect a test lamp from the relay coil voltage supply circuit to the relay control circuit and observe that the lamp does not illuminate.
- If the lamp illuminates then test the control circuit for a short to ground or a faulty control module.
4. With the ignition ON, the engine OFF, the solenoid relay removed, a test lamp connected from the relay coil voltage supply circuit to the relay control circuit, and the AIR solenoid enabled with a scan tool, observe that the test lamp illuminates.
- If the lamp does not illuminate then test the relay control circuit for high resistance, a short to voltage, or a faulty control module.
5. If all circuits and the control module are OK then replace the solenoid relay.

COMPONENT TESTING
Connect the relay coil connections to fused battery voltage and ground. Measure resistance through the relay contacts at 0 ohms.
- If resistance measures more than 0 ohms then replace the relay.

REPAIR INSTRUCTIONS
Control Module References for control module replacement and programming.

REPAIR VERIFICATION
With the ignition ON and the engine OFF, enable and disable the AIR solenoid with a scan tool while observing that the solenoid relay operates.