How to Measure the Four Wires of an Idle Motor?
2 Answers
Measurement method for the four wires of an idle motor: You can use the resistance range of a multimeter to measure the resistance of the four pins separately. The resistance of the coil is generally several tens of ohms. If the measured resistance values of the two sets of coils are not significantly different, it indicates that the idle motor is functioning properly. The idle motor, also known as a stepper motor, commonly comes in 3-wire, 4-wire, and 6-wire configurations, with 4-wire being the most common. It consists of two sets of coils, with the four wires connected to the ECU and power supply respectively, none of which should be grounded to avoid damaging the ECU. The idle motor is used to control the idle speed of the car. If it malfunctions or is damaged, it can affect the engine's idle operation, potentially leading to issues such as difficulty starting, unstable idle, idle shaking, idle stalling, or slow acceleration. Prompt inspection, repair, or replacement is necessary in such cases.
With decades of experience in car repair, measuring the four wires of an idle speed control valve isn't complicated—a multimeter will do the job. First, ensure the engine is off to avoid electric shock. Unplug the idle speed control valve connector, and you'll see four wires, typically in colors like red, black, white, and blue. Set the multimeter to the resistance range (200 ohms), then touch the probes to the corresponding pins on the valve: measure the resistance between them. The standard reading should be between 10 and 50 ohms. If it shows infinity (∞), the wire is broken; if the resistance is below 10 ohms, there might be a short circuit. After testing each pair of wires, check the connector terminals for oxidation or looseness. If you encounter unstable idle speeds, this test can help identify the issue—if there's heavy carbon buildup, clean the components to prevent minor problems from escalating. Remember, testing at a professional shop is always safer.
