Examination
1. The throttle position sensor is mounted on the throttle body and connected to the throttle shaft. In accordance with the angle of rotation of the valve, the ECU regulates the supply of fuel to the engine cylinders. A faulty or loose sensor can cause erratic engine operation because the ECU interprets the sensor's vibration as throttle valve movement. The diagnostic system detects a malfunction of the throttle sensor and generates a corresponding code (see paragraph 2).
2. Check the voltage supply from the control unit to the sensor. To do this, disconnect the electrical connector of the sensor and connect a voltmeter to the REF (+) and GND (-) contacts (figure 4.2). With the ignition on (the engine is not working) the voltmeter should show approximately 5.0 V. If there is no voltage, then either there is a break in the wiring from the ignition control unit to the sensor, or the ignition control unit is faulty.
3. Now check the sensor potentiometer. Connect the sensor connector and connect the voltmeter to the SIG (+) and GNO (-) connector contacts on the back side (using thin probes or needles). Turn on the ignition (do not start the engine). Close the damper completely. The voltage at the sensor contacts should be between 0.5 and 1.0 V. Now slowly open the valve and observe the change in voltage - it should increase slowly and smoothly. With the throttle fully open, the voltage should stop at 3.5-5.0 V.
4. On 4-cylinder engines produced in 1993, the throttle position sensor is structurally integrated into the throttle body and cannot be replaced separately from it. The sensor cannot be adjusted on these models. On all other models, the sensor can be adjusted. If, when checking the sensor, the signal voltage does not change as specified in paragraph. 3, try adjusting the sensor. If adjustment does not help, replace the sensor.
Adjustment
5. Loosen the sensor mounting screws (figure 4.5).
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6. Connect the voltmeter to the SIG and GND contacts of the sensor connector (see figure 4.2).
7. Set the damper to the fully closed position and rotate the sensor until the signal voltage is within 0.5-1.0 V. Tighten the sensor mounting screws.
8. Turn the damper to the fully open position. The signal voltage should be in the range of 3.5-5.0 V.
9. If the required voltage values cannot be obtained in both throttle positions, replace the sensor.
Replacement
10. This procedure is suitable for all models except 1993 4-cylinder engines. On engines of this model, the sensor is made integral with the valve body and can only be replaced as an assembly with the body.
11. Disconnect the sensor electrical connector. Loosen the screws that secure it and remove the sensor from the valve body (see figure 4.5).
12. The sensor is installed in the reverse order of removal. Align the tabs on the sensor body with the slots on the valve body. Screw in the screws, adjust the position of the sensor as above, then tighten the screws completely.