In episode 19 we scoped the TPS sensors on the throttle body. In this Episode we will wrap up the throttle body operation by checking the motor control. This motor is a bidirectional motor meaning we can reverse the polarity of our wires to change the direction of throttle blade movement. This is required to provide quick shutdown of air when letting off the accelerator. By default most electronic throttle bodies will no be fully closed when unplugged. The manufacturers do this so in the event of throttle body failure the vehicle doesn't stall. Since the default position of the throttle body is partially open we have to apply reverse power to the throttle body to close it down for idle control. During acceleration we switch power again and the motor will open the throttle blades.
The ecm will set fault codes if the current is too high or too low, if the throttle is commanded but the TPS doesn't report a change, if the tps does report a change even though the command was not given, open circuit, and if the correlation between the different tps sensors don't match.
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