P0412
2TR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0412: Secondary Air Injection System Switching Valve "A" Circuit
P0412 - Secondary Air Injection System Switching Valve "A" Circuit
DESCRIPTION
The secondary air injection system consists of an air pump, the air switching valve, a pressure sensor, the air injection control driver and the ECM. For a short time after cold engine starts, the air injection system pumps secondary air to the exhaust port of the cylinder head to purify the exhaust emissions. The secondary air is supplied by the air pump and is pumped to the exhaust port through the air switching valve.
The air injection control driver drives the air switching valve and the air pump according to command signals transmitted by the ECM. The pressure sensor detects the pressure in the secondary air passage when the air injection system is ON and OFF, and transmits pressure signal to the ECM.
The air injection control driver is not only equipped to drive the pump and valve, but also with a diagnosis function to detect malfunctions in the air injection system circuit.
HINT
As a large current is required to drive the air pump and air switching valve, an air injection control driver is included in this system.
MONITOR DESCRIPTION
The air injection control driver detects open and short circuits according to the voltages of the air pump terminal and the air switching valve terminal, and transmits diagnostic information as a signal to the ECM.
For a short time after cold engine starts, the ECM transmits command signals to the air injection control driver to drive the air pump and air switching valve.
The air injection control driver transmits an air switching valve malfunction signal to the ECM if either of the following conditions is met:
- The voltage at the air injection control driver terminal relating to the air switching valve is low despite the air injection control driver receiving command signals from the ECM to drive the air switching valve.
- The voltage at the air injection control driver terminal relating to the air switching valve is high despite the air injection control driver receiving no command signals from the ECM to drive the air switching valve.
The ECM sets the DTC based on diagnostic signals from the air injection control driver.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
Case 1:
Case 2:
TYPICAL MALFUNCTION THRESHOLDS
COMPONENT OPERATING RANGE
CONFIRMATION DRIVING PATTERN
NOTICE:
* This Air Injection Check only allows technicians to operate the Air Injection system for a maximum of 5 seconds.
Furthermore, the check can only be performed up to 4 times per trip. If the test is repeated, intervals of at least 30 seconds are required between checks.
While Air Injection system operation using the Techstream is prohibited, the Techstream display indicates the prohibition (WAIT or ERROR).
If ERROR is displayed on the Techstream during the test, stop the engine for 10 minutes, and then try again.
* Performing the Air Injection Check repeatedly may cause damage to the Air Injection system. If necessary, leave an interval of several minutes between System Check operations to prevent the system from overheating.
* When performing the Air Injection Check operation after the battery cable has been reconnected, wait for 7 minutes with the ignition switch turned to ON or the engine running.
* Turn the ignition switch off when the Air Injection Check operation finishes.
1. Start the engine and warm it up.
2. Turn the ignition switch off.
3. Connect the Techstream to the DLC3.
4. Turn the ignition switch to ON.
5. Turn the Techstream on.
6. Clear DTCs (if output) DTC Check / Clear.
7. Turn the ignition switch off and wait for at least 30 seconds.
8. Turn the ignition switch to ON and turn the Techstream on.
9. Enter the following menus: Powertrain / Engine and ECT / Utility / Secondary Air Injection Check / Automatic Mode.
10. Start the engine after the Techstream initialization is finished.
11. Perform the System Check operation by pressing ENTER (Next).
12. Perform the following to confirm the Air Injection system pending codes: Press the ENTER (Exit).
13. Check for pending DTCs.
OK:
No pending DTC is output.
14. After the "Air injection check" is completed, check for All Readiness by entering the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
15. Input the DTC: P0412.
16. Check the DTC judgment result.
HINT
* If the judgment result shows NORMAL, the system is normal.
* If the judgment result shows ABNORMAL, the system has a malfunction.
17. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
* If a permanent DTC is output, the system is malfunctioning.
* If no permanent DTC is output, the system is normal.
18. Turn the ignition switch off.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
1. INSPECT AIR SWITCHING VALVE
(a) Inspect the air switching valve Testing and Inspection.
NG -- REPLACE AIR SWITCHING VALVE Removal
OK -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (AIR SWITCHING VALVE - BODY GROUND)
(a) Disconnect the air switching valve connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(c) Reconnect the air switching valve connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (AIR SWITCHING VALVE - AIR INJECTION CONTROL DRIVER)
(a) Disconnect the air switching valve connector.
(b) Disconnect the air injection control driver connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(d) Reconnect the air switching valve connector.
(e) Reconnect the air injection control driver connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR INJECTION CONTROL DRIVER