P0122

DESCRIPTION
The Throttle Position (TP) sensor mounts on the side of the throttle body and is connected to the throttle blade shaft. The TP sensor is a variable resistor (potentiometer) whose resistance changes according to throttle blade shaft position. During acceleration, the TP sensor resistance decreases; during deceleration, the TP sensor resistance increases.
The Engine Control Module (ECM) applies a reference voltage to the TP sensor and then measures the voltage that is present on the TP sensor signal circuit. The ECM uses the TP sensor signal to adjust timing and injector pulse width. The TP sensor signal along with the MAF sensor signal is used by the ECM to calculate engine load.




FAILURE CONDITIONS
The ECM will set P0121 and the Malfunction Indicator Lamp (MIL) will turn on if the engine load indicated by the Throttle Position (TP) sensor and the Mass Air Flow (MAF) sensor are different. This code indicates that the throttle position and air flow readings by the TP and MAF sensor, or ECM, do not result in an expected engine load value. The ECM will set P0122 and the Malfunction Indicator Lamp (MIL) will turn on if TP sensor signal falls below 40% of the pre-programmed value (based on engine load) stored in the ECM for more than 0.2 seconds. This code indicates a lower than expected throttle position angle being read by the TP sensor or ECM.
The ECM will set P0123 and the Malfunction Indicator Lamp (MIL) will turn on if TP sensor signal rises above 130% of the pre-programmed value (based on engine load) stored in the ECM. This code indicates a higher than expected throttle position being read by the TP sensor or ECM.

NOTE: The standard resistance value between terminals 1 and 3 of the throttle position sensor is 1600 - 2500 ohms.

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TEST PROCEDURE