P0121

DTC P0121 Throttle Position Sensor Circuit Range/Performance Problem

DESCRIPTION




The Throttle Position Sensor (TPS) is mounted on the throttle body and detects the opening angle of the throttle plate. The TPS is a variable resistor (potentiometer) whose characteristic is the resistance changing according to the throttle angle. During acceleration, the TPS resistance between the reference 5V and the signal terminal decreases and output voltage increases; during deceleration, the TPS resistance increases and TPS output voltage decreases. The ECM supplies a reference 5 V to the TPS and the output voltage increases directly with the opening of the throttle valve. The TPS output voltage will vary from 0.2-0.8 V at closed throttle to 4.3-4.8 V at wide-open throttle. The ECM determines operating conditions such as idle (closed throttle), part load, acceleration/deceleration, and wide-open throttle from the TPS. Also The ECM uses the Mass Air Flow Sensor (MAFS) signal along with the TPS signal to adjust fuel injection duration and ignition timing.

DTC Detecting Condition:

Specifications:

Schematic Diagram:

Signal Waveform:

Step 1 - 2:

Step 3:

INSPECTION PROCEDURE