STOP AND START SYSTEM(for 2WW), 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 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 stores 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 continue 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

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 the engine warms up and check that the engine speed is within 50 rpm of the target idle speed.


    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 the 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 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 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 the 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

B002AH3E05
B0029Y4E05

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 OFF A
      ON B

    B

    USE SIMULATION METHOD TO CHECK Click here

    A

  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
      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
      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. B0029Z4C48
      *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
      A62-37 (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)

    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. 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 - A62-9 (MREL) Always Below 1 Ω
      EFI-MAIN NO. 1 relay terminal 1 - Body ground Always 10 kΩ or higher
      A62-9 (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 ASSEMBLY Click 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)

    B0029MCC67
    *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