DTC P0505: Idle Control System Low Input - 2.2L & Legacy 2.5L M/T

Turn ignition on. Using voltmeter connected to ground, backprobe ECM connector B134 (35-pin connector) terminal No. 5. See Figure. If voltage is more than 3 volts, repair poor contact in ECM connector. If voltage is 3 volts or less, go to next step.
Turn ignition off. Disconnect IAC solenoid valve connector. Turn ignition on. Check voltage between ground and IAC solenoid valve connector terminal No. 2. See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check for open in wiring between IAC solenoid valve and main relay. See appropriate wiring diagram in WIRING DIAGRAMS article.
Turn ignition off. Disconnect ECM connector B134 (35-pin connector). Measure resistance between IAC solenoid connector terminal No. 1 and ECM connector B134 (35-pin connector) terminal No. 5. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in wiring or poor contact between ECM and IAC solenoid valve connectors.
With ECM connector B134 (35-pin connector) disconnected, measure resistance between ground and terminal No. 5. If resistance is less than 10 ohms, repair wiring for short to ground between ECM and IAC solenoid valve connectors. If resistance is 10 ohms or more, go to next step.
Measure resistance between ground and IAC solenoid valve connector terminal No. 3. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in wiring between ground and IAC solenoid valve connector.
Check for poor contact in ECM and IAC solenoid valve connectors. Repair connectors as necessary. If connectors are okay, replace IAC solenoid valve.