Throttle Actuator Motor Basics
The fuel injection computer is the one that opens and closes the throttle plate and it does this thru' the throttle actuator motor.
The throttle actuator motor is a basic two wire motor that gets power and Ground to operate.
As mentioned earlier, this voltage is applied in a pulse width modulated (PWM) way. In plain English, this means that voltage is applied as a very rapid ON/OFF signal. ON-time is when voltage is being applied to the motor and OFF-time is when voltage is turned off.
By controlling the duty cycle (ON-time) of the voltage signal, the fuel injection computer can control the voltage 'strength' it sends to the throttle actuator motor. Thus this duty cycle then determines the throttle plate's angle.
The two wires that feed this power and Ground are the yellow (YEL) and brown (BRN) wires of the throttle body's electrical connector.
Throttle Plate Basics
The throttle plate is never fully closed since it's slightly open. This due to the fact that the throttle plate is spring loaded in both directions.
To explain this a bit further, if you push down on the throttle plate (to completely close it) and let go, it will return back to its slightly open position.
If you open the throttle plate to its wide open throttle position (WOT) and release it; it'll return back to its slightly open position.
Throttle Body Testing Essentials
It is not recommended to dynamically test the TP sensors, within the throttle body, with a multimeter in Volts mode.
I'll explain what I mean: In the older non-TAC system (where you have an accelerator cable connecting the accelerator pedal to the throttle plate) you could test the TPS by manually opening and closing the throttle plate while the TPS is connected to its electrical connector and with the key ON (but the engine OFF).
In the TAC systems, you should not do this or you run the risk of having the computer command the throttle plate to close on your fingers (since you'd have to open and close the throttle plate by hand).
The best and most accurate way of testing to see if the electronic throttle body is defective is by resistance testing both throttle position sensors within it. You can find the tests here:
Where To Buy The Electronic Throttle Body And Save
The following links will help you comparison shop for the electronic throttle body for the 2007-2008 3.5L Chevrolet Malibu:
Not sure if the electronic throttle body will fit your particular GM vehicle? Don't worry, once you get to the site, they'll make sure it fits. If it doesn't, they'll find you the right one.
More 3.5L V6 Chevy Malibu Tutorials
You can find a complete list of 3.5L V6 Chevy Malibu tutorials here: GM 3.5L V6 Index Of Articles.
Here's a list of articles you'll find there:
- How To Test The Engine Compression (2004-2007 3.5L Chevrolet Malibu).
- How To Do A Cylinder Balance Test (2004-2007 3.5L Malibu).
- How To Test A Blown Head Gasket (2004-2007 3.5L Malibu).
- How To Test The MAF Sensor (2004-2008 3.5L Malibu).
If this info saved the day, buy me a beer!
