Throttle Plate Position Controller (TPPC) Outputs

The purpose of the TPPC is to maintain the throttle position at the desired throttle angle. It is a separate chip embedded in the PCM. The desired angle is communicated from the main CPU via a 312.5 Hz duty cycle (DC) signal. The TPPC interprets the duty cycle signal as follows:

• Less than 4% - Out of range, limp home default position.
• Greater than or equal to 4% but less than 6% - Commanded default position, closed.
• Greater than or equal to 6% but less than 7% - Commanded default position. Used for key ON, engine OFF.
• Greater than or equal to 7% but less than 8% - Enable ice breaker mode. Used to clear potential ice buildup in the throttle body.
• Greater than or equal to 8% but less than 10% - Closed against hard-stop. Used to learn zero throttle angle position (hard stop) after key-up.
• Greater than or equal to 10% but less than or equal to 92% - Normal operation, between 0 degrees (hard stop) and 82 degrees, 10% duty cycle equals 0 degrees throttle angle, 92% duty cycle equals 82 degrees throttle angle.
• Greater than 92% but less than or equal to 96% - Wide open throttle, 82 to 86 degrees throttle angle.
• Greater than 96% but less than or equal to 100% - Out of range, limp home default position.

The desired angle is relative to the hard-stop angle. The hard stop angle is learned during each key-up process before the main CPU requests the throttle plate be closed against the hard stop. The output of the TPPC is a voltage request to the H driver (also in PCM). The H driver is capable of positive or negative voltage to the electronic throttle body motor.