Faulty Throttle Actuator Control (TAC) Motor
Throttle Actuator Control (TAC) Motor harness is open or shorted
Throttle Actuator Control (TAC) Motor circuit poor electrical connection
Faulty Powertrain Control Module (PCM)
Engine Light ON (or Service Engine Soon Warning Light)
The electronic Throttle Actuator Control (TAC) is a DC motor controlled by the Powertrain Control Module (PCM). There are 2 designs for the TAC, parallel and inline. The parallel design has the motor under the bore parallel to the plate shaft. The motor housing is integrated into the main housing. The inline design has a separate motor housing. An internal spring is used in both designs to return the throttle plate to a default position. The default position is typically a throttle angle of 7 to 8 degrees from the hard stop angle. The closed throttle plate hard stop prevents the throttle from binding in the bore. This hard stop setting is not adjustable and is set to result in less airflow than the minimum engine airflow required at idle. The P2118 code is sets the current necessary to operate the TAC motor is higher than a calibrated limit.