The Throttle Position Sensor (TPS) is mounted on the throttle body and detects the opening angle of the throttle plate. The TPS has 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 PCM supplies a reference 5V to the TPS and the output voltage increases directly with the opening of the throttle valve. The PCM determines operating conditions such as idle (closed throttle), part load, acceleration/deceleration, and wide-open throttle from the TPS. Also The PCM uses the Mass Air Flow Sensor (MAFS) signal along with the TPS signal to adjust fuel injection duration and ignition timing.
ECM sets DTC P0122 if the ECM detects signal voltage lower than the possible range of a properly operating TPS.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Voltage range check | ● Open in power supply harness ● Short to ground in power supply or signal harness ● Contact resistance in connectors ● Faulty TPS sensor |
Enable Conditions | ● 6 < Battery voltage < 16V | |
Threshold Value | ● Voltage < 0.14 V | |
Diagnostic Time | ● 1 sec. | |
MIL On Condition | ● 2 Driving Cycles |
Test Condition | Scan Tool Parameter | Scan Tool Screen | |
TPS VOLTAGE 1 | |||
Normal value with ignition "ON" & engine "OFF" | Accelerator pedal released | 0.20~0.47V | Fig.1 |
Normal value with engine ON & accelerator pedal fully depressed | 4.2~4.7V | - | |
Abnormal value with ignition "ON" & engine "OFF" | Power circuit open | 0.01V | Fig. 2 |
Ground circuit open | 4.99V | Fig. 3 | |
TPS signal circuit open | 4.99V | Fig.4 | |
TPS signal circuit short to ground | Approx. 0V | - | |
TPS signal circuit short to battery | Above 4.99V | - | |
