STOP AND START SYSTEM, Diagnostic DTC:P2531

DTC Code DTC Name
P2531 Ignition Switch Run Position Circuit Low

DESCRIPTION

When the ignition switch off signal is received, although communication with the ECM is normal during idling stop, the engine stop and start ECU stores P2531, but the stop and start cancel indicator light does not blink.

DTC No. DTC Detection Condition Trouble Area
P2531

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


  • No ignition switch on signal detected by engine stop and start ECU

  • When communication with the ECM is normal.

  • Harness or connector

  • NO. 1 integration relay

  • Ignition switch assembly

  • Certification ECU

    (Smart key ECU assembly)

  • Engine stop and start ECU

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. After troubleshooting, perform the following steps to recheck for DTCs and check if the Stop and Start system operates normally.

    Tech Tips


    • If the battery terminal has been disconnected, the stop and start will be prohibited. In this case, drive the vehicle for 15 to 40 minutes to permit the stop and start operation.

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


    1. for Manual transaxle


      1. Connect the intelligent tester to the DLC3.

      2. Clear the DTCs Click here.

      3. Start the engine and warm it up.

      4. Drive the vehicle at 20 km/h (12.4 mph) or more.

      5. Stop the vehicle, allow the engine to stop due to Stop and Start system control and wait for 3 seconds or more.

      6. Depress the clutch pedal to allow the engine to restart.

        Tech Tips

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

      7. Check that no DTCs are output Click here.

    2. for CVT


      1. Connect the intelligent tester to the DLC3.

      2. Clear the DTCs Click here.

      3. Start the engine and warm it up.

      4. Drive the vehicle at 20 km/h (12.4 mph) or more.

      5. Stop the vehicle, allow the engine to stop due to Stop and Start system control and wait for 3 seconds or more.

      6. Release the brake pedal to allow the engine to restart. (with the shift lever in D)

        Tech Tips

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

      7. Check that no DTCs are output Click here.

  2. Check if the Stop and Start system operates normally.

    Tech Tips

    If the battery terminal has been disconnected, the stop and start will be prohibited. In this case, drive the vehicle for 15 to 40 minutes to permit the stop and start operation.


    1. for Manual transaxle


      1. Warm up the engine.

      2. Turn the air conditioning system off.

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

      4. Stop the vehicle. Move the shift lever to neutral and release the clutch pedal.

      5. Check that the engine stops.

      6. Depress the clutch pedal and check that the engine restarts.

    2. for CVT


      1. Warm up the engine.

      2. Turn the air conditioning system off.

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

      4. Stop the vehicle with the shift lever in D and depressed the brake pedal.

      5. Check that the engine stops.

      6. Release the brake pedal and check that the engine restarts.

WIRING DIAGRAM

A005MC8E03

CAUTION / NOTICE / HINT

Note


  • If the engine stop and start ECU is being replaced, register the previously recorded number of starter operations into the new engine stop and start ECU Click here.

  • After the engine stop and start ECU is replaced or after an air conditioner kit is installed, clear the A/C information stored in the engine stop and start ECU Click here.

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

  • After the engine stop and start ECU or airbag sensor assembly (yaw rate sensor) is replaced, initialize and calibrate 0 point of deceleration sensor Click here.

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (IG SWITCH SIGNAL)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

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

    5. Read the value displayed on the tester.

      Result
      Result Proceed to
      ON A
      OFF B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - INTEGRATION RELAY)


    1. Disconnect the F75 engine stop and start ECU connector.

    2. Remove the No. 1 integration relay from the engine room sub relay block.

    3. Disconnect the 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
      F75-4 (IG2) - 1D-8 (IG2 Relay) Always Below 1 Ω
      F75-19 (IG2) or 1D-8 (IG2 Relay) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. A005M2YE02
      Text In Illustration
      *a

      Component without harness connected

      (No. 1 integration relay)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1C-1 - 1D-8 Battery voltage not applied 10 kΩ or higher
      Battery voltage applied to terminals 1D-17 and 1E-10 Below 1 Ω

    NG

    REPLACE NO. 1 INTEGRATION RELAY (IG2 RELAY)

    OK

  4. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - BODY GROUND)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1E-10 - Body ground Always Below 1 Ω
      Result
      Result Proceed to
      OK (w/o Entry and Start System) A
      OK (w/ Entry and Start System) B
      NG C

    B

    CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY-CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  5. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - IGNITION SWITCH ASSEMBLY)


    1. Disconnect the F13 ignition switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1D-17 - F13-6 (IG2) Always Below 1 Ω
      1D-17 or F13-6 (IG2) - Body ground Always 10 kΩ or higher

    3. Reconnect the F13 ignition switch connector.

      Result
      Result Proceed to
      NG A
      OK B

    A

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    B

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

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


    1. Disconnect the F65 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1D-17 - F65-9 (IG2D) Always Below 1 Ω
      1D-17 or F65-9 (IG2D) - Body ground Always 10 kΩ or higher

    3. Reconnect the F65 certification ECU (smart key ECU assembly) connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - INTEGRATION RELAY)


    1. Disconnect the A53 engine stop and start ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A53-11 (+B) - 1D-22 (EFI RELAY) Always Below 1 Ω
      A53-11 (+B) or 1D-22 (EFI RELAY) - Body ground Always 10 kΩ or higher

    3. Reinstall the No. 1 integration relay from the engine room sub relay block.

    4. Reconnect the No. 1 integration relay connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. INSPECT ECM (IGSW VOLTAGE)


    1. A005LBLE01
      Text in Illustration
      *a

      Front view of wire harness connector:

      (to ECM)

      Disconnect the A58 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 Switch Condition Specified Condition
      A58-37 (IGSW) - Body ground Ignition switch ON 8 to 14 V

    NG

    INSPECT ECM POWER SOURCE CIRCUIT Click here

    OK

  9. INSPECT INTEGRATION NO.1 RELAY (EFI RELAY)


    1. A005M2YE02
      Text in Illustration
      *a

      Component without harness connected:

      (Integration Relay)

      Remove the No. 1 integration relay from the engine sub room relay block.

    2. Disconnect the integration relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1D-22 - 1C-1 Battery voltage not applied 10 kΩ or higher
      Battery voltage applied to terminals 1D-7 and 1E-10 Below 1 Ω

    NG

    REPLACE NO. 1 INTEGRATION RELAY (EFI RELAY)

    OK

  10. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM)

    Tech Tips

    If the data in the ECM can be read using the intelligent tester even when 30 seconds or more have elapsed after the ignition switch is turned off, there may be a malfunction in the EFI relay circuit.


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1D-7 - A58-46 (MREL) Always Below 1 Ω
      1D-7 or A58-46 (MREL) - Body ground Always 10 kΩ or higher

    2. Reinstall the No. 1 integration relay from the engine sub room relay block.

    3. Reconnect the integration relay connector.

    4. Reconnect the A58 ECM connector.

      Result
      Result Proceed to
      OK (w/o Entry and Start System) A
      OK (w/ Entry and Start System) B
      NG C

    B

    INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  11. INSPECT IGNITION SWITCH ASSEMBLY


    1. Inspect the ignition switch assembly Click here.


    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE IGNITION SWITCH ASSEMBLY Click here

  12. INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    A005HR1E01
    Text In Illustration
    *a

    Component with harness connected

    Certification ECU (Smart key ECU assembly)

    		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F65-9 (IG2D) - Body ground Ignition switch off Below 1 V
      Ignition switch ON (+B)-2 V or higher

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)