Detection of throttle position sensor?

The throttle is controlled by the driver through the accelerator pedal, which changes the air intake of the engine, thus controlling the operation of the engine. Different throttle opening marks different working states of the engine. In order to meet the requirements of different working conditions, the electronically controlled gasoline injection system is equipped with a throttle position sensor on the throttle body. It can convert the throttle opening into an electrical signal and send it to ECU as the basis for ECU to judge the working condition of the engine. There are two types of throttle position sensors: switch output type and linear variable resistance output type.

1, throttle position sensor detection with switch output

(1) structure and circuit

The throttle position sensor with switch output is also called throttle switch. It has two pairs of contacts, namely idle contact (IDL) and full load contact (PSW). As shown in figure 1, the cam coaxial with the throttle valve controls the opening and closing of two switch contacts. When the throttle valve is in the fully closed position, the idle contact IDL is closed, and the ECU judges that the engine is in idle working condition according to the closing signal of the idle switch, so as to control the fuel injection quantity according to the requirements of idle working condition; When the throttle valve is opened, the idle contact is opened, and ECU controls fuel injection under the transition condition from idle speed to light load according to this signal; The fully loaded contact is always open from the fully closed throttle position to the middle and small opening. When the throttle valve is opened to a certain angle (Toyota 1G-EU is 55), the full-load contact begins to close, and a signal that the engine is in full-load operation is sent to the ECU, and the ECU performs full-load enrichment control according to the signal. The switch output throttle position sensor used in the electronic control system of Toyota 1G-EU engine, and its connection circuit with ECU is shown in Figure 2.

(2) Inspection and adjustment of throttle position sensor with switch output (Toyota 1S-E and 2S-E).

① Check the continuity between terminals on the bus.

Turn the ignition switch to the "OFF" position, unplug the throttle position sensor connector, and insert a thickness gauge with appropriate thickness between the throttle limit screw and the limit lever; As shown in Figure 3, use multimeter Ω to measure the continuity of idle contact and full load contact on the throttle position sensor connector.

When the throttle valve is fully closed, the idle contact IDL should be turned on; When the throttle valve is fully open or nearly fully open, the full load contact PSW should be opened; At other openings, both contacts should be non-conductive. See table 1 for details. Otherwise, adjust or replace the throttle position sensor.