Throttle Position Sensor (TPS)


The logic module uses this sensor to determine the position of the throttle plate.  This information is used to detect if the throttle plate is closed, wide open, partially open, and the rate of change of throttle position.  The sensor is basically a potentiometer with an overall resistance of 5,000 ohms, +/- 25%.  5V is placed across the resistance strip and the rake, which is attached to the throttle plate, provides the output voltage.

The output of the sensor is interpreted as follows:  closed throttle has 0V output or 10 degrees of opening, wide open throttle (WOT) ranges from 2.60V to 3.00V or 79.3 degrees to 90 degrees of opening, and partial throttle positions range between 0V to 2.60V or 10 degrees and 79.3 degrees of opening.  The closed throttle position is used to determine when the accelerator is not being pressed so that the logic module can set the AIS motor to the target idle speed.  The wide open throttle (WOT) position is used to determine when the accelerator is floored so that the logic module can go out of closed-loop to richen the mixture for turbo engines.  This information is also used to shut off the A/C compressor to provide more power at WOT.  The partial throttle positions are used to improve the reaction time of the air/fuel mixture adjustment and to control the wastegate on turbo engines for smoother engine performance.  The rate of change of the throttle position is used to determine when the accelerator has been quickly pressed so that the logic module can momentarily richen the mixture to provide better engine performance (accelerator pump action).

Fault Codes

If the throttle position sensor (TPS) output voltage is below 0.16V or above 4.7V, a fault code 24 is stored, the power loss light is turned on, and the system will enter limp-in mode.  The logic module will then use the MAP sensor as an indication of the throttle position.  A MAP sensor voltage less than 2.0V is considered closed throttle and a MAP sensor voltage greater than 2.0V is considered wide open throttle (WOT).

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Updated 12/19/2003.

Copyright © 1996-2003 Russ W. Knize.