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Home >> Lexus >> 2021 >> LS 500 Base, AWD >> Repair and Diagnosis (Single Page) >> Transmission >> Transmission Control Systems >> Electronic A/T Shift Lever System (Aga0F) - Diagnostics - Introduction (1 Of 2) >> Electronic Shift Lever System >> System Description [10/2023 - ] >> System Description [10/2023 - ]

System Description [10/2023 - ]

  1. SYSTEM DESCRIPTION 

    The electronic shift lever system electrically controls the transmission parking lock mechanism and shift control mechanism.

    The shift control ECU judges the vehicle condition based on the information from each sensor, switch and ECU and performs appropriate shift control based on the driver's operation of the shift lever or P position switch.

    If a malfunction occurs in the electronic shift lever system, the master warning light illuminates in the combination meter assembly (according to the malfunction mode, the shift position indicator (P, R, N, D, M) turns off (not in all cases)), the MIL turns on (not in all cases) and a warning message is also displayed on the multi-information display.

    When the shift control ECU detects a malfunction, the DTC is stored in the ECM.

  2. SHIFT POSITION INDICATOR CONTROL 
    1. Shift position indicator (P, R, N, D, M) ON (indicator illuminated (normal)) or OFF (indicator off (not normal)) is displayed.
      SHIFT POSITION INDICATOR

      DTC No. Indicator Suspected Cause
      P0850-11 Normal Park/Neutral Switch Circuit Short to Ground
      P0850-15 Normal Park/Neutral Switch Circuit Short to Battery or Open
      P085D-46 Normal Gear Shift Control Module "A" Calibration / Parameter Memory Failure
      P085D-94 May turn off Gear Shift Control Module "A" Unexpected Operation
      P08A6-00 Normal Gear Lever Position Sensor Correlation Failure
      P08A6-62 Normal Gear Lever Position Sensor Signal Compare Failure
      P1760-87 Normal Lost Communication with Sub Battery Module Missing Message
      P1761-A2 Normal Gear Shift Control Module "A" System Voltage Low
      P1765-A2 May turn off Sub Battery Module System Voltage Low
      P1769-49 Goes off Gear Shift Control Module "A" Internal Electronic Failure
      P176A-87 Normal Lost Communication with Fail Safe Signal (Gear Shift Control Module "A") Missing Message
      P176B-9F Normal Fail Safe Signal (Gear Shift Control Module "A") Stuck Off
      P176D-12 Normal IG2 Signal (Gear Shift Control Module "A") Circuit Short to Battery
      P1779-49 May turn off Gear Shift Control Module Backup Power Supply Internal Electronic Failure
      P1779-96 May turn off Gear Shift Control Module Backup Power Supply Component Internal Failure
      P177A-87 Normal Lost Communication with Gear Shift Control Module Backup Power Supply Missing Message
      P1834-11 Normal Gear Lever Y Position Sensor 1 Circuit Short to Ground
      P1834-15 Normal Gear Lever Y Position Sensor 1 Circuit Short to Battery or Open
      P183A-11 Normal Gear Lever Y Position Sensor 2 Circuit Short to Ground
      P183A-15 Normal Gear Lever Y Position Sensor 2 Circuit Short to Battery or Open
      P183F-12 Normal Gear Lever X Position Sensor 1 Circuit Short to Battery
      P183F-14 Normal Gear Lever X Position Sensor 1 Circuit Short to Ground or Open
      P1845-12 Normal Gear Lever X Position Sensor 2 Circuit Short to Battery
      P1845-14 Normal Gear Lever X Position Sensor 2 Circuit Short to Ground or Open
      P1C89-49 Goes off Park Pawl Motor Control System (Initially Drive) Internal Electronic Failure
      P1C8A-49 Goes off Park Pawl Motor Control System (Learning Value of Shift Immovable Scope) Internal Electronic Failure
      P1C8B-49 Goes off Park Pawl Motor Control System (Switching Control Lock/Unlock) Internal Electronic Failure
      P1C8C-49 Goes off Park Pawl Motor Control System (Lock/Unlock Position Learning) Internal Electronic Failure
      P1C8D-49 Goes off Park Pawl Motor Control System (After Lock/Unlock Position Learning) Internal Electronic Failure
      P1C8E-49 Goes off Park Pawl Motor Control System (Driving Request) Internal Electronic Failure
      P1C8F-14 Goes off Park Pawl Motor Phase U Circuit Short to Ground or Open
      P1C94-14 Goes off Park Pawl Motor Phase V Circuit Short to Ground or Open
      P1C99-14 Goes off Park Pawl Motor Phase W Circuit Short to Ground or Open
      P272C-00 Goes off Park Pawl Motor Driving Time Too Long
      P272C-73 Normal Park Pawl Motor Relay System Actuator Stuck Closed
      U0100-00 Normal Lost Communication with ECM/PCM "A" Missing Message (Powertrain Bus)
      U0103-87 Goes off Lost Communication with Gear Shift Control Module "A" Missing Message
      U0140-00 Normal Lost Communication with Body Control Module (Sub) Missing Message
      U1107-00 Normal Lost Communication with Power Management Module (Gear Shift Control Module "A")
      U1170-00 Normal Lost Communication with Brake System Control Module (Gear Shift Control Module "A")
  3. REJECT FUNCTION 
    1. A reject function is equipped to reject incorrect shift switching when the shift lever is operated incorrectly.
    2. When the reject function operates, the current shift state is maintained or switches to the neutral (N). The buzzer in the combination meter assembly sounds (2 times consecutively or once) and the master warning light blinks. Also, the recommended handling method is displayed on the multi-information display.
      REJECT FUNCTION OPERATION CHART

      Shift operation performed by reject function Shift state after reject function operation Message displayed on multi-information display
      Changes the shift state when battery voltage was low Maintains current shift state Battery low
      Shifting unavailable
      See owner's Service Information
      Changes the shift state to and from park (P) within a short period of time Maintains current shift state Shifting unavailable
      Wait a moment and
      Shift again
      Changes the shift state from park (P) or neutral (N) to manual (M) Maintains current shift state Vehicle must be in D
      to shift into M
      • Changes the shift state to drive (D), reverse (R) or manual (M) when the engine switch is on (IG) and the engine is stopped
      • Changes the shift state from park (P) when the engine is cranking
      • Changes the shift state from park (P) when the required voltage to change the shift state is not available
      		 Maintains current shift state Engine must be started
      to shift
      • Changes the shift state from park (P) with brake pedal not depressed
      • When the vehicle is stopped, the driver attempted to change the shift position without depressing the brake pedal, after the power of the shift control ECU was temporarily cut off
      • Changes the shift state from neutral (N) to drive (D) or reverse (R) without depressing the brake pedal while the vehicle is stopped
      		 Maintains current shift state Press Brake to Shift
      Changes the shift state directly to manual (M) from reverse (R) Neutral (N) Shifted into N
      Vehicle must be in D
      to shift into M
      Changes the shift state to drive (D) while backing up Neutral (N) Shifted into N
      Vehicle must be stopped
      to shift into D
      Changes the shift state to reverse (R) while driving forward Neutral (N) Shifted into N
      Vehicle must be stopped
      to shift into R
      P position switch was pressed short when driving Maintains current shift state -
      P position switch was pressed repeatedly or held pressed when driving Neutral (N) Shifted into N
      Vehicle must be stopped
      to shift into D
      • Changes the shift state form park (P) when accelerator and brake pedals depressed simultaneously
      • Changes the shift state from neutral (N) to drive (D) or reverse (R) with accelerator pedal depressed
      • Park (P)
      • Neutral (N)
      		 Release accelerator to shift
      Changes the shift state to neutral (N) when the system detects the shift lever was moved to N but not enough time elapsed for manual switching Maintains current shift state* Temporarily hold shift lever
      in N position
      to shift into N

      *: The shift state may shift to neutral (N) depending on the driving conditions.

  4. N RANGE HOLD MODE OPERATION 
    1. The engine switch can be turned off while holding the shift state neutral (N) by performing the following operation.
      1. Change the shift state neutral (N).
      2. Return the shift lever to the home position.
      3. Move the shift state neutral (N) again (the buzzer sounds).
      4. Turn the engine switch off with the shift state held in the neutral (N) or within 5 seconds after releasing the shift lever (the buzzer will sound and a confirmation message will be displayed on the multi-information display).

        HINT: 

        • Pressing the P switch will switch the shift state to park (P) and exit from N range hold mode.
        • Do not operate the engine switch unnecessarily while in N range hold mode except in an emergency. Repeating this operation 5 times will switch the shift state to park (P) and exit from N range hold mode.
  5. AUTOMATIC PARK (P) SWITCHING CHANGING FUNCTION WHEN EXITING 

    If it is detected that the driver has exited the vehicle* while the shift state not park (P), the shift state will be changed to park (P) automatically.

    *: The driver seat belt buckle is off, the driver seat door is open, and the brake pedal is released.

    HINT: 

    This does not operate while the vehicle is driven. This function (auto-shifting function) operates if the driver exits the vehicle while the shift state not park (P). It does not function at all times.

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