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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






TYPICAL SCAN TOOL DATA

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
Ignition ON, enable and disable the AIR solenoid with a scan tool while observing that the AIR solenoid relay operates.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the solenoid relay.
2. Ignition ON, connect a test lamp between the positive terminal at the battery and the relay control circuit terminal.
3. Command the relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the relay control circuit for a short to ground. If the circuit tests normal, replace the control module.
- If the test lamp is always OFF, test the relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the control module.
4. Connect a 10 A fused jumper wire between the positive voltage terminal at the battery and the solenoid voltage supply circuit terminal and verify solenoid activation.
- If the solenoid does not activate, test the solenoid voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the solenoid.
5. Ignition ON, connect a 10 amp fused jumper wire between the relay switch voltage supply circuit terminal and the solenoid voltage supply circuit terminal and verify solenoid activation.
- If the solenoid does not activate, test the relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test or replace the relay.
6. Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal and ground.
- If the test lamp does not illuminate, test the affected relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test or replace the relay.
7. If all circuits and the control module test normal, test or replace the relay.

COMPONENT TESTING

Relay Test
1. Test between the normally-closed switch terminals, if any, for 0 ohms.
2. Test between the normally-open switch terminals for infinite ohms.
3. Test between each switch terminal and either coil terminal for infinite ohms.
4. Connect the relay coil terminals to ground and fused power to energize the relay.
5. Test between each switch terminal and each coil terminal for 0 volts.
6. Test between the normally-closed switch terminals, if any, for infinite ohms.
7. Test between the normally-open switch terminals for 0 ohms.

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.
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