My husband just recently bought me a 99 montero sport xls. We are having a few problems with it and need some advice considering we have a very limited budget. The check engine light is on and when we took it to Auto Zone the code popped up P0505 possible Idle air control motor problem. It does idle slightly rough and "jumps" at certain speeds when accelerating. When it jumps the rpm's swiftly drop then jump right back to where they were. However it has not dies. So first my husband went home and cleaned out the throttle body. Didn't help. Next we bought and installed new idle control motor. I admit it helped some, meaning it's idling slightly less roughly than it was and the jumps aren't quite as noticeable when accelerating. The check engine light came on within minutes. Husband had it hooked back up at auto zone and of course it's the same code. Any ideas on what it could be? Some people have already suggested engine control computer, wiring connector to the iac and wiring harness. Any of these sound plausible? BTW had new alternator, battery and tune up done last august by previous owner. I'm hoping we don't have to take it to a dealer. Any advice or suggestions are welcome!

 

It could very well be the connector or the harness. Check to make sure the zip tube is tightly fitted to the throttle body. Next, inspect the IAC valve circuit, and the air conditioning signal circuit. A competent technician should be able to inspect those for you. Was the replacement an OE or aftermarket part?

 

It was OE part. Thanks i will have those checked as soon as i am able.

 

Let us know how you get along, good luck!