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 when communication with the ECM is normal, the engine stop and start ECU will output 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

  • Instrument panel junction block assembly (IG2 NO. 2 relay)

  • No. 1 integration relay (EFI MAIN relay)

  • Ignition or starter switch 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 battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item Status of Battery Charge Control changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery temperature at 11°C (51°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item Status of Battery Charge Control cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.

      If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.-

    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.

    7. Keep the engine stopped by stop and start control for 1 second or more.

    8. Depress the clutch pedal and start the engine.

      Tech Tips

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

    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 battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item Status of Battery Charge Control changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery temperature at 11°C (51°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item Status of Battery Charge Control cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.

      If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.


    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.

    5. Allow the engine to stop by stop and start control.

    6. Depress the clutch pedal and start the engine.

WIRING DIAGRAM

A001SCVE01

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.

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


    1. Disconnect the F77 engine stop and start ECU connector.

    2. Remove the instrument panel 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
      F77-18 (IG2) - 3D-19 Always Below 1 Ω
      F77-18 (IG2) - Body ground and other terminals Always 10 kΩ or higher
      3D-19 - Body ground and other terminals 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 NO. 2 RELAY)


    1. Remove the instrument panel junction block assembly.

      Click here

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

      A001UY6C01
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      3L-1 - 3D-19 Battery voltage is not applied to terminals 3A-17 and 3D-3 10 kΩ or higher
      3L-1 - 3D-19 Battery voltage is applied to terminals 3A-17 and 3D-3 Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  4. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG2 NO. 2 RELAY) - BODY GROUND)


    1. Remove the instrument panel junction block assembly.

      Click here

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3D-3 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG2 NO. 2 RELAY) - IGNITION OR STARTER SWITCH ASSEMBLY)


    1. Remove the instrument panel junction block assembly.

      Click here

    2. Disconnect the F12 ignition or starter switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3A-17 - F12-8 (IG1) Always Below 1 Ω
      3A-17 - Body ground and other terminals Always 10 kΩ or higher
      F12-8 (IG1) - Body ground and other terminals 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 - NO. 1 INTEGRATION RELAY (EFI MAIN RELAY))


    1. Disconnect the A62 engine stop and start ECU connector.

    2. Disconnect the 1B No. 1 integration relay connector.

      Click here

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A62-1 (+B) - 1B-4 Always Below 1 Ω
      A62-1 (+B) - Body ground and other terminals Always 10 kΩ or higher
      1B-4 - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Inspect the No. 1 integration relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 1 INTEGRATION RELAY (EFI MAIN RELAY) Click here

    OK

  8. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY (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 NO. 1 relay circuit is suspected.


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

    2. Disconnect the A38 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1B-5 - A38-46 (MREL) Always Below 1 Ω
      1B-5 - Body ground and other terminals Always 10 kΩ or higher
      A38-46 (MREL) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. INSPECT IGNITION OR STARTER SWITCH ASSEMBLY


    1. Inspect the ignition or starter switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY Click here