DTC P1510-P1515: IDLE AIR CONTROL (IAC) SOLENOID VALVE SIGNAL No. 1-3 CIRCUITS HIGH/LOW INPUT - EXCEPT IMPREZA & LEGACY 2.2L (CALIFORNIA EMISSIONS)

Turn ignition off. Disconnect IAC solenoid valve connector. Turn ignition on. Using voltmeter connected to ground, check voltage at IAC solenoid valve connector terminal No. 2. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in wiring or poor contact between main relay and IAC solenoid valve connector.
Check voltage between ground and IAC solenoid valve connector terminal No. 5. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in wiring or poor contact between main relay and IAC solenoid valve connector.

Turn ignition off. Using an ohmmeter, check resistance between specified ECM and IAC connector terminals. See IAC SOLENOID VALVE RESISTANCE table. If resistance is less than one ohm on all circuits, go to next step. If resistance is one or more ohm on any circuit, repair open in wiring or poor contact between ECM connector B134 and IAC solenoid valve connector.

IAC SOLENOID VALVE RESISTANCE

IAC Solenoid Valve No.	ECM Connector B134 Terminal No.	IAC Solenoid Valve Connector Terminal No.
1	5	4
2	6	1
3	19	6

Ensure ignition is off. Disconnect appropriate ECM connector. Measure resistance between ground and ECM connector B134 terminals No. 5, 6 and 19. If resistance is less than 10 ohms on any circuit, repair short in wiring between ECM and IAC solenoid valve connectors. If resistance is 10 ohms or more on all circuits, go to next step.
Check for poor contact at ECM and IAC solenoid valve connectors. Repair connections as necessary. If connections are okay, replace IAC solenoid valve.