Throttle Position Sensor: Testing and Inspection

OPERATION
- The throttle position sensor converts the throttle position opening into a voltage and inputs it to the engine control module, which then controls the fuel injection based on the input signal.
- The 5 V power in the engine control module is supplied to the throttle position sensor. Through the resistor in the sensor, it is grounded in the engine control module.
- As the throttle valve shaft rotates from the idle position to wide open position, the resistance between the variable resistor terminal of the throttle position sensor and the ground terminal increases. As a result, the voltage at the throttle position sensor variable resistance terminal also increases.

TROUBLESHOOTING HINTS
Hint 1: The throttle position sensor signal is more important in the control of automatic transaxle than in the engine control. Shifting shock and other troubles will be caused if this sensor is faulty.
Hint 2: If the output voltage of the throttle position sensor is out of specification, adjust the sensor and check the voltage again. If there is an evidence of disturbed fixed SAS setting, adjust the fixed SAS.

INSPECTION





Using Scan Tool

HARNESS INSPECTION





Measure the power supply voltage of the throttle position sensor.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): 4.8 - 5.2
OK: GO TO STEP 2
NG: Repair the harness. (A1-42)





Check for continuity of the ground circuit.
- Connector: Disconnected
OK: GO TO STEP 3
NG: Repair the harness. (A4-49)





Check for an open-circuit, or a short-circuit to ground between the engine control module and the throttle position sensor.
- Throttle position sensor connector: Disconnected
- Engine control module connector: Disconnected
- Connector of any control module which uses TPS output signals like ECM: Disconnected
OK: STOP
NG: Repair the harness. (A2-78)

THROTTLE POSITION SENSOR CHECK





(1) Disconnect the throttle position sensor connector.





(2) Measure resistance between terminal (4) (sensor ground) and terminal (1) (sensor power).

Standard value: 3.5 - 6.5 k-ohm





(3) Connect a pointer type ohmmeter between terminal (4) (sensor ground) and terminal (2) (sensor output).
(4) Operate the throttle valve slowly from the idle position to the full open position and check that the resistance changes smoothly in proportion with the throttle valve opening angle.
(5) If the resistance is out of specification, or tails to change smoothly, replace the throttle position sensor.

Throttle position sensor installation torque: 2.0 Nm (1.5 ft.lbs.)