Possible causes

– Faulty Idle Control System motor
– Idle Control System motor harness is open or shorted
– Idle Control System motor circuit poor electrical connection
– Faulty Powertrain or Engine Control Module
– Vaccum leaks or damaged hoses or improper routing

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Engine hard to start
– Rough or erratic idle speed

P0505 CHRYSLER Description

The throttle body has an air control passage that provides air for the engine at idle (the throttle plate is closed). The IAC motor pintle protrudes into the air control passage Throttle Body Air Control Passage and regulates air flow through it. Based on various sensor inputs, the powertrain control module (PCM) adjusts engine idle speed by moving the IAC motor pintle in and out of the air control passage. The IAC motor is positioned when the ignition key is turned to the On position.