Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptors
DTC P0412 : Secondary Air Injection (AIR) Solenoid Control CircuitDTC P0418 : Secondary Air Injection (AIR) Pump Control Circuit
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Solenoid Relay Coil Supply | P0412 | P0411, P0412 | P0690 | -- |
Solenoid Relay Control | P0412 | P0411, P0412 | P0411, P0412, P0690 | -- |
Solenoid Relay Switch Supply | P0411 | P0411 | -- | -- |
Pump Relay Coil Supply | P0102, P0412, P0418, | P0418 | P0690, P0418 | -- |
Pump Relay Control | P0418 | P0418 | P0411, P0418, P0690, P2431 | -- |
Pump Relay Switch Supply | P0411 | P0411 | -- | -- |
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. The secondary AIR injection pump, provides filtered air on demand to the AIR check valve assembly. The AIR check valve assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR CNTRL relay supplies the current needed to operate the AIR solenoid that is integral to the check valve assembly. A pressure sensor, also integral to the check valve assembly, 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 signal circuit provides the control module with a voltage relative to internal AIR pressure changes.
The AIR diagnostic uses 3 phases to test the AIR system:
| • | DTCs P0411 and P2430 run during Phase 1 |
| • | DTCs P2430 and P2440 run during Phase 2 |
| • | 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 solenoid, pressure sensor , 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 250 ms loop. |
| • | DTC P0412 and DTC P0418 run continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The actual and expected states of the AIR solenoid and AIR pump relay control circuits do not match. |
| • | The condition exists for at least 5 seconds. |
Action Taken When the DTC Sets
DTCs P0412 and P0418 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0412 and P0418 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Description and Operation Reference
Secondary Air Injection System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Ignition ON, command the affected relay ON and OFF with a scan tool. Feel or listen to verify that the affected relay turns ON and OFF with each command.
- Engine running, observe the DTC information with a scan tool. DTCs P0412 or P0418 should not set.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the affected relay.
- Ignition ON, connect a test lamp between the positive terminal at the battery and the relay control circuit terminal.
- Command the relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- Connect an appropriately fused jumper wire between the positive voltage terminal at the battery and the load voltage supply circuit terminal and verify load activation.
- Ignition ON, connect an appropriately fused jumper wire between the relay switch voltage supply circuit terminal and the load voltage supply circuit terminal and verify load activation.
- Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal and ground.
- If all circuits and the ECM test normal, test or replace the affected relay.
| ⇒ | If the test lamp is always ON, test the relay control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | 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 ECM. |
| ⇒ | If the load does not activate, test the load voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the load. |
| ⇒ | If the load 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 all components connected to the fuse and replace as necessary. |
| ⇒ | If the test lamp does not illuminate, test the relay coil voltage supply circuit for a short to ground or an open/high resistance. |
Component Testing
Relay Test
- Test between the normally-closed switch terminals, if any, for 0 ohms.
- Test between the normally-open switch terminals for infinite ohms.
- Test between each switch terminal and either coil terminal for infinite ohms.
- Connect the relay coil terminals to ground and fused power to energize the relay.
- Test between the normally-closed switch terminals, if any, for infinite ohms.
- Test between the normally-open switch terminals for 0 ohms.
- Test between each switch terminal and either coil terminal for 0 volts.
Repair Verification
Ignition ON, command the relay ON and OFF with a scan tool. Feel or listen to verify that the relay turns ON and OFF with each command.
