Camry 3.0L V6

Electronic Throttle Control System (ETCS) consists of throttle body, accelerator pedal position sensor, Throttle Position (TP) sensor, throttle control motor and Engine Control Module (ECM). ETCS uses the ECM to calculate throttle valve opening in the throttle body in relation to driving conditions. There is no accelerator cable used with the ETCS. ETCS controls idle speed and cruise control system operation. On A/T models, the throttle control is synchronized with the electronically controlled transaxle during shifting to reduce shift shock during transaxle shifting. On models with traction control, the throttle valve is closed by demand signal from skid control Electronic Control Unit (ECU) if an excessive amount of slippage is created by a driving wheel. On models with vehicle skid control, throttle valve opening is controlled in conjunction with coordinating control with the skid control ECU to provide operation of vehicle skid control system. On all applications, accelerator pedal position sensor is mounted near accelerator pedal. See Fig 1. Accelerator pedal position sensor consists of 2 internal sensors which deliver accelerator pedal position signals to the ECM to indicate throttle valve opening. TP sensor consists of 2 internal sensors which delivers input signals to ECM. ECM uses various input signals for operating throttle control motor. Throttle control motor is mounted on side of throttle body and operates throttle valve. See Fig 1.

ETCS consists of various fail-safe features. If malfunction occurs in either one of the 2 internal sensors in accelerator pedal position sensor, the ECM detects the abnormal voltage signal difference between the 2 sensor circuits and switches to the limp mode. In limp mode, the remaining sensor circuit is used to calculate accelerator pedal position. If malfunction occurs in both internal sensors in accelerator pedal position sensor, the ECM detects the abnormal voltage signal difference between the 2 sensors circuits and regards that accelerator pedal is released and continues throttle control in which the vehicle may be driven at idle speed. If malfunction occurs in either one of the 2 internal sensors in TP sensor, the ECM detects the abnormal voltage signal difference between the 2 sensor circuits and switches to limp mode in which voltage to throttle control motor is turned off and throttle control motor becomes inoperative. Throttle return spring will position throttle valve at a designated position in which the vehicle may be driven. If problem exists with throttle control motor, ECM will switch to limp mode in which voltage to throttle control motor is turned off and throttle control motor becomes inoperative. Throttle return spring will position throttle valve at a designated position in which the vehicle may be driven.

In the event of an ETCS malfunction, Malfunction Indicator Light (MIL) will be illuminated and Diagnostic Trouble Code (DTC) will be stored in ECM. MIL is displayed as an engine icon on instrument cluster on instrument panel. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieval of DTCs.

Fig 1: Locating Electronic Throttle Control System Components On Throttle Body & Accelerator Pedal Position Sensor (Camry 3.0L V6)

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