Aug 30, 2019 · When one or more of these variables is off it can lead to a rough idling condition. Most of the time the culprit is going to be the ignition system, although there are a myriad of other causes. We’ll cover the most common causes of rough idle below. Ford Ranger Rough Idle Causes. Hopefully, the check engine light is on. C5 Corvette Idle Relearn Oct 22, 2020 · Measure the resistance of the solenoid in a Ford. Locate the idle control motor in your Ford vehicle and identify the two electrical pins on the solenoid. Connect an Ohm meter to the two and measure the resistance between them. Fords are designed to operate with the resistance in the solenoid in a range between 7.0 to 13.0 ohms.