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 ignition or starter switch assembly*1 or certification ECU (smart key ECU assembly)*2 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):


  • Ignition switch OFF signal is input.

  • Communication with the ECM is normal.

  • Wire harness or connector

  • No. 1 integration relay (for 1WW)

  • IG2 relay (except 1WW)

  • EFI MAIN relay (for 1WW)

  • EFI-MAIN relay (except 1WW)

  • Ignition or starter switch assembly (w/o Entry and Start System)

  • Certification ECU (Smart key ECU assembly) (w/ Entry and Start System)

  • 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 automatically 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 40 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 ignition switch to ON 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. Stop the vehicle, move the shift lever to neutral and release the clutch pedal. (for Manual Transaxle)

    7. Depress the brake pedal and stop the vehicle. (for CVT)

    8. Keep the engine stopped by stop and start control for 1 second or more. (Keep the shift lever in D. (for CVT))

    9. Depress the clutch pedal and start the engine. (for Manual Transaxle)

      Tech Tips

      If the engine cranks slowly when the engine is restarted, it can be determined that the battery voltage is low.

    10. Release the brake pedal with the shift lever in D to start the engine. (for CVT)

      Tech Tips

      If the engine cranks slowly when the engine is restarted, it can be determined that the battery voltage is low.

    11. 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 40 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. Stop the vehicle, move the shift lever to neutral and release the clutch pedal. (for Manual Transaxle)

    5. Depress the brake pedal and stop the vehicle. (for CVT)

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

    7. Depress the clutch pedal and start the engine. (for Manual Transaxle)

    8. Release the brake pedal with the shift lever in D to start the engine. (for CVT)

WIRING DIAGRAM


  1. for 1WW

    B0044G7E01
    B0044EVE01

  2. except 1WW

    B0043W3E01
    B0044K6E01

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 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 ignition switch to ON.

    3. Turn the GTS on.

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


      Powertrain > Stop and Start > Data List
      Tester Display
      IG Switch

    5. Read the value displayed on the GTS.

      Result
      Tester Display Result Proceed to
      IG Switch ON A
      OFF (for 1WW) B
      OFF (except 1WW) C

    A

    USE SIMULATION METHOD TO CHECK Click here

    C

    CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - IG2 RELAY) Click here

    B

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - NO. 1 INTEGRATION RELAY (IG2 RELAY))


    1. Disconnect the A50 ECM connector.

    2. Disconnect the E24 engine stop and start ECU connector.

    3. Disconnect the 1I No. 1 integration relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E24-20 (IG2) - 1I-4 Always Below 1 Ω
      E24-20 (IG2) - Body ground Always 10 kΩ or higher
      1I-4 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


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

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 1 INTEGRATION RELAY (IG2 RELAY) Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (IG2 RELAY) - BODY GROUND)


    1. Disconnect the 1I 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
      1I-2 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (IG2 RELAY) - IGNITION OR STARTER SWITCH ASSEMBLY OR CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Disconnect the 1I No. 1 integration relay connector.

    2. Disconnect the E4 ignition or starter switch assembly connector (w/o Entry and Start System).

    3. Disconnect the E33 certification ECU (smart key ECU assembly) connector (w/ Entry and Start System).

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

      Standard Resistance
      w/o Entry and Start System
      Tester Connection Condition Specified Condition
      1I-3 - E4-3 (IG2) Always Below 1 Ω
      1I-3 - Body ground Always 10 kΩ or higher
      E4-3 (IG2) - Body ground Always 10 kΩ or higher
      w/ Entry and Start System
      Tester Connection Condition Specified Condition
      1I-3 - E33-9 (IG2D) Always Below 1 Ω
      1I-3 - Body ground Always 10 kΩ or higher
      E33-9 (IG2D) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - EFI MAIN RELAY)


    1. Disconnect the A8 engine stop and start ECU connector.

    2. Remove the EFI MAIN relay from engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A8-5 (+B) - EFI MAIN relay terminal 3 Always Below 1 Ω
      A8-5 (+B) - Body ground Always 10 kΩ or higher
      EFI MAIN relay terminal 3 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK ECM (IGSW TERMINAL VOLTAGE)


    1. Disconnect the A50 ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A50-26 (IGSW) - Body ground Ignition switch ON 9.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  8. INSPECT RELAY (EFI MAIN RELAY)


    1. Inspect the EFI MAIN relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (EFI MAIN RELAY)

    OK

  9. CHECK HARNESS AND CONNECTOR (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 ignition switch off a malfunction in the EFI MAIN relay circuit is suspected.


    1. Remove the EFI MAIN relay from engine room relay block and junction block assembly.

    2. Disconnect the A50 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      EFI MAIN relay terminal 2 - A50-9 (MREL) Always Below 1 Ω
      EFI MAIN relay terminal 2 - Body ground Always 10 kΩ or higher
      A50-9 (MREL) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (w/o Entry and Start System) A
      OK (w/ Entry and Start System) B
      NG C

    A

    GO TO STEP 18 Click here

    B

    GO TO STEP 19 Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  10. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - IG2 RELAY)


    1. Disconnect the A173*1 or A169*2 ECM connector.


      • *1: for 8NR-FTS

      • *2: for 1ND-TV w/ Glow Plug Controller

    2. Disconnect the E24 engine stop and start ECU connector.

    3. Remove the IG2 relay from engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E24-20 (IG2) - IG2 relay terminal 5 Always Below 1 Ω
      E24-20 (IG2) - Body ground Always 10 kΩ or higher
      IG2 relay terminal 5 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. INSPECT RELAY (IG2 RELAY)


    1. Inspect the IG2 relay.

      for 1ND-TV: Click here

      for 8NR-FTS: Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (IG2 RELAY)

    OK

  12. CHECK HARNESS AND CONNECTOR (IG2 RELAY - BODY GROUND)


    1. Remove the IG2 relay from engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      IG2 relay terminal 2 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  13. CHECK HARNESS AND CONNECTOR (IG2 RELAY - IGNITION OR STARTER SWITCH ASSEMBLY OR CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Remove the IG2 relay from engine room relay block and junction block assembly.

    2. Disconnect the E4 ignition or starter switch assembly connector (w/o Entry and Start System).

    3. Disconnect the E33 certification ECU (smart key ECU assembly) connector (w/ Entry and Start System).

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

      Standard Resistance
      w/o Entry and Start System
      Tester Connection Condition Specified Condition
      IG2 relay terminal 1 - E4-3 (IG2) Always Below 1 Ω
      IG2 relay terminal 1 - Body ground Always 10 kΩ or higher
      E4-3 (IG2) - Body ground Always 10 kΩ or higher
      w/ Entry and Start System
      Tester Connection Condition Specified Condition
      IG2 relay terminal 1 - E33-9 (IG2D) Always Below 1 Ω
      IG2 relay terminal 1 - Body ground Always 10 kΩ or higher
      E33-9 (IG2D) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  14. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - EFI-MAIN RELAY)


    1. Disconnect the A8 engine stop and start ECU connector.

    2. Remove the EFI-MAIN relay from engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A8-5 (+B) - EFI-MAIN relay terminal 3 Always Below 1 Ω
      A8-5 (+B) - Body ground Always 10 kΩ or higher
      EFI-MAIN relay terminal 3 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  15. CHECK ECM (IGSW TERMINAL VOLTAGE)


    1. Disconnect the A173*1 or A169*2 ECM connector.


      • *1: for 8NR-FTS

      • *2: for 1ND-TV w/ Glow Plug Controller

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      for 8NR-FTS
      Tester Connection Condition Specified Condition
      A173-6 (IGSW) - Body ground Ignition switch ON 9.5 to 14 V
      for 1ND-TV w/ Glow Plug Controller
      Tester Connection Condition Specified Condition
      A169-37 (IGSW) - Body ground Ignition switch ON 9.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECM POWER SOURCE CIRCUIT for 1ND-TV w/ Glow Plug Controller: Click here
    GO TO ECM POWER SOURCE CIRCUIT for 1WW: Click here
    GO TO ECM POWER SOURCE CIRCUIT for 8NR-FTS: Click here

    OK

  16. INSPECT RELAY (EFI-MAIN RELAY)


    1. Inspect the EFI-MAIN relay.

      for 1ND-TV: Click here

      for 8NR-FTS: Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (EFI-MAIN RELAY)

    OK

  17. CHECK HARNESS AND CONNECTOR (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 ignition switch off a malfunction in the EFI-MAIN relay circuit is suspected.


    1. Remove the EFI-MAIN relay from engine room relay block and junction block assembly.

    2. Disconnect the A173*1 or A169*2 ECM connector.


      • *1: for 8NR-FTS

      • *2: for 1ND-TV w/ Glow Plug Controller

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

      Standard Resistance
      for 8NR-FTS
      Tester Connection Condition Specified Condition
      EFI-MAIN relay terminal 1 - A173-46 (MREL) Always Below 1 Ω
      EFI-MAIN relay terminal 1 - Body ground Always 10 kΩ or higher
      A173-46 (MREL) - Body ground Always 10 kΩ or higher
      for 1ND-TV w/ Glow Plug Controller
      Tester Connection Condition Specified Condition
      EFI-MAIN relay terminal 1 - A169-9 (MREL) Always Below 1 Ω
      EFI-MAIN relay terminal 1 - Body ground Always 10 kΩ or higher
      A169-9 (MREL) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (w/o Entry and Start System) A
      OK (w/ Entry and Start System) B
      NG C

    B

    CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (IG2D TERMINAL VOLTAGE) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  18. INSPECT IGNITION OR STARTER SWITCH ASSEMBLY


    1. Inspect the ignition or starter switch assembly.

      for 1ND-TV: Click here

      for 1WW: Click here

      for 8NR-FTS: Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY for 1ND-TV: Click here
    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY for 1WW: Click here
    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY for 8NR-FTS: Click here

  19. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (IG2D TERMINAL VOLTAGE)


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

      B004416C34
      *a

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      E33-9 (IG2D) - Body ground Ignition switch ACC 1 V or less
      E33-9 (IG2D) - Body ground Ignition switch ON 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)