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Home >> Toyota >> 2020 >> Corolla L >> Repair and Diagnosis >> External Pages >> Different car >> Section 324 (Meter / Gauge System (12.3 Inch) - Diagnostic Codes, Symptom Tests & Circuit Tests) >> METER / GAUGE SYSTEM (for 12.3 Inch Display) >> Speed Signal Circuit [11/2022 - ] >> Description

Speed Signal Circuit [11/2022 - ]: Description

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  1. SPEED SIGNAL CIRCUIT CONTROL 
    1. The wheel speed sensors produce an output that varies according to the vehicle speed.
    2. The wheel speed sensor output is received by the skid control ECU (brake actuator assembly) which uses this information to create the vehicle speed signal.
    3. The vehicle speed signal is output from the skid control ECU (brake actuator assembly) to the certification ECU (smart key ECU assembly) and then to the combination meter assembly.
    4. To create this signal, 12 V is output from terminal SI of the combination meter assembly to the certification ECU (smart key ECU assembly).
    5. The pulse signal is created by switching the transistor in the certification ECU (smart key ECU assembly) on and off, making the voltage on the wire drop to 0 V.
    6. A similar system is used for the output of this signal from the combination meter assembly via terminal +S.
    7. A voltage of 12 V or 5 V is applied to terminal +S from each ECU or relay that is connected to this terminal.
    8. The transistor in the combination meter assembly is controlled by the signal from the certification ECU (smart key ECU assembly). When this transistor is turned on, this transistor makes the voltage supplied by the various ECUs (via their respective internal resistors) drop to 0 V.
    9. Each ECU connected to terminal +S of the combination meter assembly controls its respective system based on this pulse signal.
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