STOP AND START SYSTEM, Diagnostic DTC:P1780

DTC Code DTC Name
P1780 Discrepancy between Neutral Position SW and Shift Position

DESCRIPTION

The engine stop and start ECU detects a malfunction by comparing the shift position signal with the neutral position sensor (neutral position switch) signal input state. When a malfunction occurs, the engine stop and start ECU stores this DTC, blinks the stop and start cancel indicator light, and prohibits the stop and start control.

DTC No.

DTC Detection Condition

Trouble Area

P1780

The following condition continues for 1 second or more (1 trip detection logic):

  • Open or short in neutral position sensor (neutral position switch) circuit.

  • Neutral position sensor (neutral position switch)

  • Engine stop and start ECU

  • Wire harness or connector

WIRING DIAGRAM

A285528E36

CAUTION / NOTICE / HINT

Note:

  • Before replacing the engine stop and start ECU, read the number of starter operations and write it into a new engine stop and start ECU (Click here).

  • After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU (Click here).

  • After replacing the engine stop and start ECU or yaw rate sensor, perform deceleration sensor zero point clear and calibration (Click here).

  • Inspect the fuses for circuits related to this system before performing the following procedure.

Tip:

Using the GTS, read the freeze frame data before troubleshooting. System condition information is recorded as freeze frame data the moment a DTC is stored. This information can be useful when troubleshooting (Click here).

PROCEDURE

  1. READ VALUE USING GTS (NEUTRAL SWITCH)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Stop and Start / Data List / Neutral Switch.

    5. Read the value when the shift lever is in neutral and any other position

      OK

      GTS Display

      Condition

      Normal Condition

      Neutral Switch

      Shift lever in neutral

      ON

      Shift lever in any position other than neutral

      OFF

    USE SIMULATION METHOD TO CHECK

    (Click here)

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - NEUTRAL POSITION SENSOR (NEUTRAL POSITION SWITCH))

    1. Disconnect the A74 engine stop and start ECU connector.

    2. Disconnect the D7 neutral position sensor (neutral position switch) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A74-26 (TMVC) - D7-1 (W1)

      Always

      Below 1 Ω

      A74-25 (TME2) - D7-3 (F+)

      Always

      Below 1 Ω

      A74-27 (TMN) - D7-2 (TMN)

      Always

      Below 1 Ω

      A74-26 (TMVC) - Body ground

      Always

      10 kΩ or higher

      D7-1 (W1) - Body ground

      Always

      10 kΩ or higher

      A74-25 (TME2) - Body ground

      Always

      10 kΩ or higher

      D7-3 (F+) - Body ground

      Always

      10 kΩ or higher

      A74-27 (TMN) - Body ground

      Always

      10 kΩ or higher

      D7-2 (TMN) - Body ground

      Always

      10 kΩ or higher

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  3. CHECK ENGINE STOP AND START ECU (TMN TERMINAL VOLTAGE)

    1. Measure the voltage according to the value(s) in the table below.

      U122074E02
      Table 1. Text in Illustration

      *a

      Component with harness connected

      (Engine Stop and Start ECU)

      -

      -

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A74-27 (TMN) - A74-25 (TME2)

      Ignition switch ON, shift lever in neutral

      2.7 to 4.3 V

      Ignition switch ON, shift lever in any position other than neutral

      0.7 to 1.9 V

    REPLACE ENGINE STOP AND START ECU

    (Click here)

    REPLACE NEUTRAL POSITION SWITCH

    (Click here)