DTC    P2531    Ignition Switch Run Position Circuit Low


DESCRIPTION

The EFI relay turns off approximately 3 to 4 seconds after the ignition switch is turned off, shutting off the power supply to the engine stop and start ECU. Therefore, if the ECM is in the IG-ON state, the engine stop and start ECU should also be in the IG-ON state.
If ignition switch signals are not detected for a certain time period even while the ignition switch is ON, it is determined that there is an open in the ignition switch signal circuit and this DTC will be stored.

DTC No.
DTC Detection Condition
Trouble Area
P2531
Both of the following conditions continue for 60 seconds or more (1 trip detection logic):
  1. No ignition switch on signal detected by engine stop and start ECU.
  2. Vehicle stopped.
  1. Harness or connector
  2. Engine stop and start ECU

HINT:
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).


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

HINT:
  1. If the ECM learned values have been cleared by disconnecting the battery or for another reason, Stop and Start system control will be prohibited until ECM learning completes.
  2. 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 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 and stop the vehicle to allow the engine to stop due to Stop and Start system control.

  5. Wait for at least 90 seconds. Depress the clutch pedal to allow the engine to restart and idle for at least 10 seconds.

    HINT:
    Depending on the vehicle conditions, the engine may restart in less than 90 seconds.

  6. Check that no DTCs are output (Click here).


Check if the Stop and Start system operates normally.

HINT:
If the battery terminal has been disconnected, the ECO OFF indicator will be illuminated. In this case, drive the vehicle for 15 to 40 minutes to turn off the indicator.

  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.


WIRING DIAGRAM


A217702E01


INSPECTION PROCEDURE

NOTICE:
  1. 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).
  2. 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).
  3. Inspect the fuses for circuits related to this system before performing the following inspection procedure.

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

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

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

  1. Read the value displayed on the tester.
    Result 
    Result
    		Proceed to
    ON
    		A
    OFF
    		B



B
Go to step 2
A

USE SIMULATION METHOD TO CHECK (Click here)  

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

  1. Disconnect the engine stop and start ECU connector.

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    D78-19 (IGSW) - 1D-10 (IG2 Relay)
    		Always
    		Below 1 Ω
    D78-19 (IGSW) or 1D-10 (IG2 Relay) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the engine stop and start ECU connector.

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


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


    A200843E02

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1A-1 - 1D-10
    		Battery voltage not applied
    		10 kΩ or higher
    Battery voltage applied to terminals 1D-11 and 1C-3
    		Below 1 Ω

    Text in Illustration 
    *1
    		Component without harness connected:
    (Integration Relay)

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPLACE INTEGRATION NO.1 RELAY (IG2 RELAY)
OK


4.CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - BATTERY)

  1. Disconnect the cable from the negative (-) battery terminal.

  1. Disconnect the cable from the positive (+) battery terminal.

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1A-1 - Battery positive terminal
    		Always
    		Below 1 Ω
    1A-1 or Battery positive terminal - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.

  1. Reconnect the cable to the positive (+) battery terminal.

  1. Reconnect the cable to the negative (-) battery terminal.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


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

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1C-3 - Body ground
    		Always
    		Below 1 Ω

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

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



B
Go to step 6

C
Go to step 8
A

REPAIR OR REPLACE HARNESS OR CONNECTOR 

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

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

  1. Disconnect the integration relay connector.

  1. Disconnect the ignition switch connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1D-11 - D28-6 (IG2)
    		Always
    		Below 1 Ω
    1D-11 or D28-6 (IG2) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.

  1. Reconnect the ignition switch assembly connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


7.INSPECT IGNITION SWITCH ASSEMBLY


    A203952E06

  1. Remove the ignition switch.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    All Terminals
    		LOCK
    		10 kΩ or higher
    2 - 3
    		ACC
    		Below 1 Ω
    2 - 3 - 4, 6 - 7
    		ON
    1 - 2 - 4, 6 - 7 - 8
    		START

    Text in Illustration 
    *1
    		Ignition Switch Position
    *2
    		Component without harness connected:
    (Ignition Switch)
    Result 
    Result
    		Proceed to
    NG
    		A
    OK
    		B

  1. Reinstall the ignition switch.



B
Go to step 9
A

REPLACE IGNITION SWITCH ASSEMBLY (Click here)  

8.CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - POWER MANAGEMENT ECU)

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

  1. Disconnect the integration relay connector.

  1. Disconnect the D36 power management ECU connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1D-11 - D36-8 (IG2D)
    		Always
    		Below 1 Ω
    1D-11 or D36-8 (IG2D) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.

  1. Reconnect the power management ECU connector.



NG
REPAIR OR REPLACE ENTRY AND START SYSTEM (IG2D CIRCUIT) (Click here)
OK


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

  1. Disconnect the engine stop and start ECU connector.

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    D79-6 (+B) - 1C-1 (EFI RELAY)
    		Always
    		Below 1 Ω
    D79-6 (+B) or 1C-1 (EFI RELAY) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the engine stop and start ECU connector.

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


10.INSPECT ECM (IGSW VOLTAGE)


    A148741E40

  1. Disconnect the ECM connector.

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A18-27 (IGSW) - Body ground
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector:
    (to ECM)

  1. Reconnect the ECM connector.



NG
CHECK HARNESS OR CONNECTOR (IGSW CIRCUIT FOR ECM) (Click here)
OK


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


    A200843E02

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1C-1 - 1A-1
    		Battery voltage not applied
    		10 kΩ or higher
    Battery voltage applied to terminals 1B-2 and 1C-3
    		Below 1 Ω

    Text in Illustration 
    *1
    		Component without harness connected:
    (Integration Relay)

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPLACE INTEGRATION NO.1 RELAY (EFI RELAY)
OK


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

HINT:
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. Remove the integration relay from the No. 1 engine room relay block.

  1. Disconnect the integration relay connector.

  1. Disconnect the ECM connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1B-2 - A18-44 (MREL)
    		Always
    		Below 1 Ω
    1B-2 or A18-44 (MREL) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the ECM connector.

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


13.CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - BATTERY)

  1. Disconnect the cable from the negative (-) battery terminal.

  1. Disconnect the cable from the positive (+) battery terminal.

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1A-1 - Battery positive terminal
    		Always
    		Below 1 Ω
    1A-1 or Battery positive terminal - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.

  1. Reconnect the cable to the positive (+) battery terminal.

  1. Reconnect the cable to the negative (-) battery terminal.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


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

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

  1. Disconnect the integration relay connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1C-3 - Body ground
    		Always
    		Below 1 Ω

  1. Reconnect the integration relay connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ENGINE STOP AND START ECU (Click here)