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Home >> Lexus >> 2008 >> GX 470 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> SFI System >> DTC P0412 Secondary Air Injection System Switching Valve "A" Circuit >> Monitor Description

Monitor Description

The Air Injection Control Driver (AID) detects an open or short in the circuit according to the voltage of the air pump terminal (VP) and electromagnetic air switching valve terminal (W), and sends a signal as diagnostic information to the ECM.

The AID outputs the air switching valve terminal malfunction signal to the ECM if: 1) VV terminal voltage is low despite the AID receiving the command signal from the ECM to drive the air switching valve terminal or 2) VV terminal voltage is high despite the AID not receiving the command signal from the ECM. The ECM stores the DTC based on the diagnostic signal from the AID and illuminates the MIL.

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