Poor Idling: Surging

• Check switch condition signal circuit. See CODE 51 in appropriate articles;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES

• Check Idle Air Control (IAC) valve circuit.
• Check Volume Airflow (VAF) sensor circuit. See CODE 31 in appropriate articles;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES

• Check ECM power source circuit (ignition keyed).
• Check fuel pump control circuit. See CODE 78 in appropriate articles;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES