How to Replace the Idle Air Control (IAC) Motor in a 1999 Ford Mustang

Introduction: How to Replace the Idle Air Control (IAC) Motor in a 1999 Ford Mustang

Are you having problems with your vehicle's RPM fluctuating high and low ? Does it occur more often while running your A/C and/or other high powered auxiliary items? Does your engine sometimes even shut off? It maybe due to your Idle Air Control (IAC) Motor sticking from carbon deposits built up in it over time, causing the spring to no longer regulate the proper power to both your engine and other equipment. But don't worry, replacement is quick and easy by following these simple steps. 

Items You'll Need:
1. A new IAC Motor
2. A Socket Wrench w/ 10mm socket
3. A new gasket (optional depending on condition of current gasket)

Step 1: Locate the IAC Motor

First, pop the hood of your Mustang and locate your IAC motor. The motor is located on the passenger side toward the back of the hood. 

Step 2: Disconnect the Wire Harness From the IAC Motor

Next, locate and remove the wiring harness that is connected to the IAC Motor. This connection should pop off rather easily without much effort. 

Step 3: Remove the Bolts From the IAC Motor

Next locate the two bolts (one on top, the other on the bottom) and using your 10mm socket & wrench, remove the bolts. Be careful, once you remove the bolts, the motor will be completely unattached and will likely fall off if not supported. Also, if you are planning on re-using the current gasket make sure to support the motor once the bolts are removed so that the gasket doesn't become damaged from falling to the ground.

Step 4: Bolt, Connect, and Done!

Once the old IAC Motor has been removed, all that's left is bolting the new IAC motor (with the gasket) back to the Mustang by following the previously listed instructions in reverse order (i.e. use 10mm socket & wrench to bolt new IAC motor and gasket back on, connect the wire harness connector back into the new IAC motor, and close the hood because you're done!)

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    6 years ago

    Don't forget to reset the idle on your vehicle. I did a throttle body clean on my seville and it ran while driving like the cruise was on. On mine you went into dionogstic mode then shut the car off 3 times. But it'll vary by vehicle. I've never had to do that before on any car but then I always disconnect the negative cable besides this time. But just a tip, the answer to the cruise like idle on the mechanics forums was a bunch of computer dionogstic and parts that didnt fix it. A good no great rule to live by on cars up to 2000 is most of the time it's a easy mechanical fix. A mechanic will want to pull codes to charge 100 for a hour and 100 a hour for the mechanic, so use your common sense and you'll figure it out just fine. And do research, the net is a garage mechanic most useful tool.