I have a 1998 Plymouth Voyager (base model) with the 2.4 Liter 4 cyinder DOHC engine.
Looking for help on P0505 code, Idle Air Control Circuit.
The check engine light is on; I clear the code and the light goes out. The car can idle for quite a while without the check engine light coming back, even when I rev the engine. But as soon as I put the car in gear and start driving, the check engine light is back within a minute.
I have done everything I can find on the internet on various OBD II troubleshooting websites. I have replaced the idle air control valve/motor and the throttle position sensor. I have replaced the air filter and thoroughly cleaned the air intake and the throttle body; I have cleaned the electronic connections.
After all of this, the engine does run smoother, but the check engine light keeps coming back. The only thing I haven't done (beyond my abilities I fear) is replace the wiring harnesses.
Anybody out there have any other ideas?
The P0505 code is a code where anyone of the four IAC wires could be shorted together or shorted to voltage or to ground.
Try to wiggle the wire harness from the IAC to the PCM to see if you see any changes in IAC functioning. If you see a change then check the wire harness for short to ground.
It could be a faulty PCM if all wiring checks out ok.
I posted a chart of the wiring for the IAC to the PCM to help you find a short (or open). Disconnect both connectors and check for each wire for a short to ground or a short to each other using an OHM meter. Also checking for an open wire between the IAC connector to PCM connector.
Images used are from the Alldata Automotive information website.