STOP AND START SYSTEM(for 3ZR-FAE), 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 output DTC P2531.

  • *1: w/o Entry and Start System

  • *2: w/ Entry and Start System

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

  • IG2 relay

  • EFI-MAIN NO. 1 relay

  • 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

Tip:

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. Tip:

    • 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 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. for CVT:

      Depress the brake pedal and stop the vehicle.

      for Manual Transaxle:

      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. (for CVT: Keep the shift lever in D.)

    8. for CVT:

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

      for Manual Transaxle:

      Depress the clutch pedal and start the engine.

      Tip:

      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

    Tip:

    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. for CVT:

      Depress the brake pedal and stop the vehicle.

      for Manual Transaxle:

      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. (for CVT: Keep the shift lever in D.)

    6. for CVT:

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

      for Manual Transaxle:

      Depress the clutch pedal and start the engine.

WIRING DIAGRAM

A299563E04
A299564E04

CAUTION / NOTICE / HINT

Note:

  • for CVT:

    When replacing the engine stop and start ECU with a new one, make sure to download the previous status (number of starter operations) of the old engine stop and start ECU. After replacing the engine stop and start ECU, turn the ignition switch to ON and wait 20 seconds, then confirm that "OK" is displayed for the Data List item "Oper Prohibition (O/P Air Bleeding)". Then upload the previous status (number of starter operations) to the engine stop and start ECU.

    Click here

  • for Manual Transaxle:

    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.

Tip:

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 hereClick here

    B

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

    1. Disconnect the G87 engine stop and start ECU connector.

    2. Remove the IG2 relay from the 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

      G87-18 (IG2) - IG2 relay terminal 5

      Always

      Below 1 Ω

      G87-18 (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

  3. INSPECT RELAY (IG2 RELAY)

    1. Inspect the IG2 relay.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE RELAY (IG2-MAIN RELAY)

    OK

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

    1. Remove the IG2 relay from the 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

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

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

    2. w/ Entry and Start System:

      Disconnect the G82 certification ECU (smart key ECU assembly) connector.

    3. w/o Entry and Start System:

      Disconnect the G4 ignition or starter switch assembly connector.

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

      Standard Resistance

      Table 1. w/ Entry and Start System

      Tester Connection

      Condition

      Specified Condition

      IG2 relay terminal 1 - G82-9 (IG2D)

      Always

      Below 1 Ω

      IG2 relay terminal 1 - Body ground

      Always

      10 kΩ or higher

      G82-9 (IG2D) - Body ground

      Always

      10 kΩ or higher
      Table 2. w/o Entry and Start System

      Tester Connection

      Condition

      Specified Condition

      IG2 relay terminal 1 - G4-3 (IG2)

      Always

      Below 1 Ω

      IG2 relay terminal 1 - Body ground

      Always

      10 kΩ or higher

      G4-3 (IG2) - 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 NO. 1 RELAY)

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

    2. Remove the EFI-MAIN NO. 1 relay from the 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

      A66-1 (+B) - EFI-MAIN NO. 1 relay terminal 3

      Always

      Below 1 Ω

      A66-1 (+B) - Body ground

      Always

      10 kΩ or higher

      EFI-MAIN NO. 1 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. C267933C19

      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the 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

      A62-6 (IGSW) - Body ground

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    GO TO ECM POWER SOURCE CIRCUIT

    Click here

    OK

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

    1. Inspect the EFI-MAIN NO. 1 relay.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE RELAY (EFI-MAIN NO. 1 RELAY)

    OK

  9. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 1 RELAY - ECM)

    Tip:

    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. Remove the EFI-MAIN NO. 1 relay from the engine room relay block and junction block assembly.

    2. Disconnect the A62 ECM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      EFI-MAIN NO. 1 relay terminal 1 - A62-46 (MREL)

      Always

      Below 1 Ω

      EFI-MAIN NO. 1 relay terminal 1 - Body ground

      Always

      10 kΩ or higher

      A62-46 (MREL) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK (w/ Entry and Start System)

    OK (w/o Entry and Start System)

    NG
    OK (w/o Entry and Start System)

    INSPECT IGNITION OR STARTER SWITCH ASSEMBLYClick here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK (w/ Entry and Start System)

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

    B264896C67

    *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

      G82-9 (IG2D) - Body ground

      Ignition switch ACC

      Below 1 V

      G82-9 (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)

  11. 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