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DTC P1127: ELECTRONIC THROTTLE CONTROL SYSTEM ACTUATOR POWER SOURCE CIRCUIT Lexus LX J100

CAUTIONIf ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

Circuit Description

Battery voltage is supplied to circuit +BM at ECM harness connector E10 at all times. If DTC P1127 is present, ECM turns off power to throttle motor and magnetic clutch and throttle valve is fully closed by return spring. When this occurs, opening angle of throttle valve is controlled by the accelerator pedal by means of a throttle cable. DTC is set when ECM detects an open ETCS power source circuit. Possible causes are

  1. ETCS power source circuit is open.
  2. Defective ECM.

Diagnostic Aids

Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.