That unit does not generate a voltage. The Engine Computer sends voltage to it to adjust idle speed. It does that by varying the voltage and polarity between the wires to place the motor at the desired position. As the motor pulses to those different positions, it turns a threaded shaft that extends or retracts a "pintle" valve. That valve opens an air passage around the throttle blade. At the same time the computer varies the amount of time the injectors are pulsed open to adjust the amount of fuel entering the engine. Varying the amount of air and fuel is how the computer controls idle speed. You cannot measure those voltages with a voltmeter, and if you could, they would have no meaning.
If idle speed is not being controlled properly, the air passage could be plugged with carbon. If the battery was recently disconnected or run dead, it may be necessary to perform a specific driving procedure to cause the Engine Computer to relearn "minimum throttle". Until that is done, the computer won't know when it must be in control of idle speed. The typical symptoms for that include the engine may not start unless you hold the accelerator pedal down 1/4", you won't get the nice "idle flare-up" to 1500 rpm's at start-up, and the engine may tend to stall at stop signs.
I only know the procedure for Chrysler products. That involves driving at highway speed with the engine warmed up, then coasting for at least seven seconds without touching the pedals. Most other car brands do the relearn procedure automatically, and most people do not even know that is taking place. If your car needs to have something special done, any mechanic at the dealership will be able to tell you what to do.
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Saturday, December 3rd, 2016 AT 6:43 PM
