Hi, not sure which engine you have so I can't be precise, but here is what I recommend. Remove the idle air control valve and check the valve seat for blockage. If dirty, clean both the passages and the valve, reinstall and see if that resolves the code. If it isn't blocked or dirty, run the tests below using a volt/ohmmeter. The primary test to run is step 8. If the valve fails step 8, replace the valve. If it passes, then check the PCM reference voltages in step 7. Let me know if you have questions. Fig. IAC motor assembly Fig. IAC motor eleccomputer code p0505 -running at - jturcotte_1106.gifinouts Fig. IAC motor and driver circuits Fig. IAC motor mounting screws (arrows)
TESTING
Conclusive testing of this component requires the use of special, factory-supplied equipment and is not included here. The tests below will provide valuable information regarding condition of the IAC motor and require only a VOM.
REMOVAL & INSTALLATION
The IAC motor is located on the rear of the throttle body secured by two Torx® screws.
WARNING
When the IAC motor is removed from the throttle body, do NOT extend the pintle more than 0.250 inch (6.35mm). If the pintle is extended more than this amount, it may separate from the IAC motor and the motor will have to be replaced.
To install:
Idle control system malfunction.
The idle air control motor is on the back side of the throttle body. Make sure the connections are clean to it., but if you have to replace parts, I would start with the throttle position sensor on the side of the throttle body. It's cheaper and more likely the cause.
If its running at a high idle I would test my Throttle position sensor and the idle air valve to make sure that there working properly.Next check and make sure that all you vacuum hoses are connected and not cracked or broken.You can find a diagram on the underside of the hood or on the radiator support near the fan shroud.
SOURCE: 1999 Ram 3500 Wagon with
The IAC stepper motor is mounted to the throttle body, and regulates the amount of air bypassing the control of the throttle plate. As engine loads and ambient temperatures change, engine rpm changes. A pintle on the IAC stepper motor protrudes into a passage in the throttle body, controlling air flow through the passage. The IAC is controlled by the Powertrain Control Module (PCM) to maintain the target engine idle speed.
At idle, engine speed can be increased by retracting the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by restricting the passage with the pintle and diminishing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is moved (rotated) in steps, or increments. Opening the IAC opens an air passage around the throttle blade which increases RPM.
The PCM uses the IAC motor to control idle speed (along with timing) and to reach a desired MAP during decel (keep engine from stalling).
The IAC motor has 4 wires with 4 circuits. Two of the wires are for 12 volts and ground to supply electrical current to the motor windings to operate the stepper motor in one direction. The other 2 wires are also for 12 volts and ground to supply electrical current to operate the stepper motor in the opposite direction. To make the IAC go in the opposite direction, the PCM just reverses polarity on both windings. If only 1 wire is open, the IAC can only be moved 1 step (increment) in either direction. To keep the IAC motor in position when no movement is needed, the PCM will energize both windings at the same time. This locks the IAC motor in place.
In the IAC motor system, the PCM will count every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the memory is cleared, the PCM no longer knows the position of the pintle. So at the first key ON, the PCM drives the IAC motor closed, regardless of where it was before. This zeros the counter. From this point the PCM will back out the IAC motor and keep track of its position again.
When engine rpm is above idle speed, the IAC is used for the following:
The PCM can control polarity of the circuit to control direction of the stepper motor.
Solutions:
I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514
SOURCE: Engine code P0505 for 2002 honda odyssey
p0505 is directly related to the idle air control valve (sometimes called the rotary valve) i cant count how many of these i have replaced on hondas. It is located directly under the throttle body so it can be difficult to replace. I would recommend you having a professional replace this due to the difficulty of the valve removal
SOURCE: hello i have a 2001
well the ecu try to control the idle but if there is a leak on the intake maniful after the trotlebady it can not control it check for vamum leak may be a hose the pcv valve hose on the intake
http://engine-codes.com/p0505.htmlForum CodePossible causes- IACV-AAC valve harness is open or shorted 3,793 views
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