Detection Of Automotive Throttle Position Sensor With Switch Output

(1) Structure and circuit
The switch output type throttle position sensor is also known as the throttle switch. It has two sets of contacts, namely idle speed contact (IDL) and full load contact (PSW). The opening and closing of two switch contacts are controlled by a cam that is coaxial with the throttle valve. When the throttle valve is in the fully closed position, the idle contact IDL is closed, and the ECU determines that the engine is in idle condition based on the closing signal of the idle switch, thereby controlling the fuel injection amount according to the requirements of idle condition; When the throttle valve opens, the idle contact opens, and the ECU controls the fuel injection during the transition from idle to low load based on this signal; The full load contact is always in the open state from the fully closed position to the range of small and medium-sized opening of the throttle valve. When the throttle valve opens to a certain angle (55 ° for Toyota 1G-EU vehicles), the full load contact begins to close and sends a signal to the ECU that the engine is operating at full load. The ECU performs full load enrichment control based on this signal. The switch output type throttle position sensor used in the electronic control system of the Toyota 1G-EU engine.
(2) Check and adjust the switch output type throttle position sensor.
① Check the continuity between terminals on the vehicle
Place the ignition switch in the "OFF" position, unplug the throttle position sensor connector, and insert an appropriate thickness gauge between the throttle limit screw and limit rod; Measure the continuity of the idle contact and full load contact on the throttle position sensor connector using a multimeter Ω range.
When the throttle valve is fully closed, the idle contact IDL should be conductive; When the throttle valve is fully open or close to full open, the full load contact PSW should be conductive; At other openings, both contacts should not conduct. The specific situation is shown in Table 1. Otherwise, the throttle position sensor should be adjusted or replaced.