STOP AND START SYSTEM, Diagnostic DTC:P2531

DTC Code DTC Name
P2531 Ignition Switch Run Position Circuit Low

DESCRIPTION

If the engine stop and start ECU receives the OFF signal from the certification ECU (smart key ECU assembly) when communication with the ECM is normal, the engine stop and start ECU will store DTC P2531.

DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate Memory
P2531 Ignition Switch Run Position Circuit Low

Both of the following conditions are met for 10 seconds or more (1 trip detection logic):


  • Engine switch OFF signal is input.

  • Communication with the ECM is normal.

  • Wire harness or connector

  • Semiconductor PWR integration ECU

  • Certification ECU (Smart key ECU assembly)

  • Engine stop and start ECU

 Does not come on DTC stored

CONFIRMATION DRIVING PATTERN

Tech Tips

DTCs for the stop and start system are not cleared even if the malfunction has been repaired. After repairing the malfunction, be sure to clear the DTCs.

Click here


  1. Tech Tips


    • If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 60 minutes until refresh charge is completed and stop and start control operation is permitted.

    • Allow the engine to idle for 3 minutes after it is warmed up and check that the engine idle speed is within 50 rpm of the target idle speed.

    CONFIRMATION AFTER TROUBLESHOOTING


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG) and turn the GTS on.

    3. Clear the DTCs.

      Click here


      Powertrain > Stop and Start > Clear DTCs

    4. Start the engine and warm it up.

    5. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    6. Depress the brake pedal and stop the vehicle.

    7. Keep the engine stopped by stop and start control for 10 second or more. (Keep the shift lever in D.)

    8. Release the brake pedal with the shift lever in D to start the engine.

    9. Check that DTCs are not output.

      Click here


      Powertrain > Stop and Start > Trouble Codes

  2. STOP AND START SYSTEM OPERATION CHECK

    Tech Tips

    If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 60 minutes until refresh charge is completed and stop and start control operation is permitted.


    1. Start the engine and warm it up.

    2. Turn the air conditioning system off.

    3. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    4. Depress the brake pedal and stop the vehicle.

    5. Allow the engine to stop by stop and start control. (Keep the shift lever in D.)

    6. Release the brake pedal with the shift lever in D to start the engine.

WIRING DIAGRAM

B005LV4E04

CAUTION / NOTICE / HINT

Note


  • Before replacing the engine stop and start ECU, read the number of starter operations and total number of engine starts 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, airbag sensor assembly*1 or yaw rate sensor*2, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

    Click here


    • *1: for Optitron Meter Type

    • *2: for TFT Meter Type

  • When the engine stop and start ECU is replaced, check the oil pump with motor assembly.

    Click here

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

Tech Tips

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 (IG SWITCH)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

    5. According to the display on the GTS, read the Data List.


      Powertrain > Stop and Start > Data List
      Tester Display
      IG Switch
      Result
      Tester Display Result Proceed to
      IG Switch ON A
      OFF B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - IG2 NO. 2 RELAY)


    1. Disconnect the J46 engine stop and start ECU connector.

    2. Disconnect the 2B instrument panel junction block assembly connector.

      Click here

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J46-18 (IG2) - 2B-19 Always Below 1 Ω
      J46-18 (IG2) - Body ground Always 10 kΩ or higher
      2B-19 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG2 RELAY)


    1. Remove the instrument panel junction block assembly.

      Click here

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

      B005PPOC09
      *1

      Component without harness connected

      (Instrument Panel junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      2B-19 - 2F-1

      Battery positive (+) → 2A-17

      Battery negative (-) → 2B-3

      		 Below 1 Ω
      Battery not connected to 2A-17 and 2B-3 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG2 NO. 2 RELAY)

    OK

  4. CHECK HARNESS AND CONNECTOR (IG2 NO. 2 RELAY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Disconnect the 2A instrument panel junction block assembly connector.

      Click here

    2. Disconnect the J41 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2A-17 - J41-17 (IG1D) Always Below 1 Ω
      2A-17 - Body ground Always 10 kΩ or higher
      J41-17 (IG1D) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (IG2 RELAY)


    1. Inspect the semiconductor PWR integration ECU.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE SEMICONDUCTOR POWER INTEGRATION ECU (IG2 RELAY) Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU (IG2 RELAY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Remove the semiconductor PWR integration ECU from the No. 1 engine room relay block and No. 1 junction block assembly.

      Click here

    2. Disconnect the J41 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1E-1 - J41-17 (IG1D) Always Below 1 Ω
      1E-1 - Body ground Always 10 kΩ or higher
      J41-17 (IG1D) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - SEMICONDUCTOR PWR INTEGRATION ECU (EFI-MAIN RELAY))


    1. Disconnect the A66 engine stop and start ECU connector.

    2. Remove the semiconductor PWR integration ECU from the No. 1 engine room relay block and No. 1 junction block assembly.

      Click here

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A66-1 (+B) - 1G-8 Always Below 1 Ω
      A66-1 (+B) - Body ground Always 10 kΩ or higher
      1G-8 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK ECM (IGSW TERMINAL VOLTAGE)


    1. B005Q5UC13
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A46 ECM connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A46-6 (IGSW) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  9. INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (EFI MAIN RELAY)


    1. Inspect the semiconductor PWR integration ECU.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE SEMICONDUCTOR POWER INTEGRATION ECU (EFI MAIN RELAY) Click here

    OK

  10. CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU (EFI MAIN RELAY) - ECM)

    Tech Tips

    If communication between the GTS and vehicle is possible and SFI system data can be read 30 seconds after turning the engine switch off a malfunction in the semiconductor power integration ECU (EFI MAIN relay) circuit is suspected.


    1. Remove the semiconductor PWR integration ECU from the No. 1 engine room relay block and No. 1 junction block assembly.

      Click here

    2. Disconnect the A46 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1G-6 - A46-46 (MREL) Always Below 1 Ω
      1G-6 - Body ground Always 10 kΩ or higher
      A46-46 (MREL) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (IG1D TERMINAL VOLTAGE)

    B005P21C02
    *a

    Component with harness connected

    (Certification ECU (Smart Key ECU Assembly))

    		 - -

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A41-17 (IG1D) - Body ground Engine switch on (ACC) Below 1 V
      A41-17 (IG1D) - Body ground Engine switch on (IG) 9 V or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)