STOP AND START SYSTEM, Diagnostic DTC:P2531

DTC Code DTC Name
P2531 Ignition Switch Run Position Circuit Low

DESCRIPTION

When 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 stores DTC P2531.

DTC No. DTC Detection Condition Trouble Area
P2531

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

  • No. 1 integration relay

  • Certification ECU (smart key ECU assembly)

  • Engine stop and start ECU

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. CONFIRMATION AFTER TROUBLESHOOTING

    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.


    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.

    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 1 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.

  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

B001O7JE03

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 airbag sensor assembly, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU Click here.

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

      Result
      GTS 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 - NO. 1 INTEGRATION RELAY)


    1. Disconnect the H191 engine stop and start ECU connector.

    2. Disconnect the No. 1 integration relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H191-18 (IG2) - 1C-5 Always Below 1 Ω
      H191-18 (IG2) or 1C-5 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT INTEGRATION NO. 1 RELAY (IG2 RELAY)


    1. Inspect the No. 1 integration relay (IG2 relay) Click here.


    NG

    REPLACE NO. 1 INTEGRATION RELAY Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - BODY GROUND)


    1. Disconnect the No. 1 integration relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1E-2 - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Disconnect the No. 1 integration relay connector.

    2. Disconnect the A36 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
      1C-8 - A36-9 (IG2D) Always Below 1 Ω
      1C-8 or A36-9 (IG2D) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - NO. 1 INTEGRATION RELAY)


    1. Disconnect the No. 1 integration relay connector.

    2. Disconnect the A77 engine stop and start ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-1 (+B) - 1C-10 Always Below 1 Ω
      A77-1 (+B) or 1C-10 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT ECM (IGSW VOLTAGE)


    1. B001NPGE02
      Text in Illustration
      *a

      Front view of wire harness connector:

      (to ECM)

      Disconnect the A75 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
      A75-6 (IGSW) - Body ground Engine switch on (IG) 9.5 to 14 V

    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  8. INSPECT NO. 1 INTEGRATION RELAY (EFI MAIN RELAY)


    1. Inspect the No. 1 integration relay (EFI MAIN relay) Click here.


    NG

    REPLACE NO. 1 INTEGRATION RELAY Click here

    OK

  9. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION 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 EFI-MAIN relay circuit is suspected.


    1. Disconnect the No. 1 integration relay connector.

    2. Disconnect the A75 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1C-7 - A75-46 (MREL) Always Below 1 Ω
      1C-7 or A75-46 (MREL) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (IG2D TERMINAL VOLTAGE)


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

      B001NTGE02
      Text in Illustration
      *a

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-9 (IGSW) - Body ground Engine switch on (ACC) Below 1 V
      A36-9 (IGSW) - Body ground Engine switch on (IG) 9 V or higher

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)