STOP AND START SYSTEM, Diagnostic DTC:P1644

DTC Code DTC Name
P1644 ECU Internal Error

DESCRIPTION

If a malfunction is detected in the starter circuit, the engine stop and start ECU stores DTC P1644 and illuminates the stop and start cancel indicator light.

DTC No. DTC Detection Condition Trouble Area
P1644 Malfunction in the engine stop and start ECU internal drive circuit for the starter for 0.2 seconds or more (1 trip detection logic).

  • Wire harness or connector

  • ST relay

  • ST NO. 2 relay*1

  • Engine stop and start ECU

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


  1. After troubleshooting, perform the following steps to recheck for DTCs.

    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 (52°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.

    • 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.


    1. for Manual Transaxle


      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.

      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.

    2. for CVT


      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.

      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. Depress the brake pedal and stop the vehicle.

      7. Keep the engine stopped by stop and start control for 1 second or more (Keep the shift lever in D).

      8. Release the brake pedal with the shift lever in D to 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.

  2. Check if the stop and start system operates normally.

    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 (52°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. for Manual Transaxle


      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.

    2. for CVT


      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. Depress the brake pedal and stop the vehicle.

      5. Keep the engine stopped by stop and start control for 1 second or more (Keep the shift lever in D).

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

WIRING DIAGRAM

Refer to P0617 Click here.

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 inspection procedure.

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.

  • 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.

  • If DTCs P060B and P1644 are output simultaneously, perform troubleshooting for DTC P060B (Analog to Digital Converter Malfunction) first as it may have caused DTC P1644 (ECU Internal Error) to be stored.

  • If DTCs P0641 and P1644 are output simultaneously, perform troubleshooting for DTC P0641 (Sensor Reference Voltage "A" Circuit/Open) first as it may have caused DTC P1644 (ECU Internal Error) to be stored.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P1644)


    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 / Trouble Codes.

    5. Check for other DTCs.

      Result
      Result Proceed to
      DTC P1644 is output (for CVT) A
      DTC P1644 is output (for Manual Transaxle) B
      DTC P060B and DTC P1644 are output C
      DTC P0641 and DTC P1644 are output D

    B

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

    C

    GO TO DTC P060B Click here

    D

    GO TO DTC P0641 Click here

    A

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


    1. Disconnect the A90 power management control ECU connector.

    2. Disconnect the B100 park/neutral position switch connector.

    3. Disconnect the A92 engine stop and start ECU.

    4. Remove the ST relay from engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A92-21 (STA) - ST relay holder 2 Always Below 1 Ω
      A92-21 (STA) or ST relay holder 2 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - PARK/NEUTRAL POSITION SWITCH)


    1. Disconnect the A92 engine stop and start ECU.

    2. Disconnect the B100 park/neutral position switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A92-21 (STA) - B100-9 (L) Always Below 1 Ω
      A92-21 (STA) or B100-9 (L) - Body ground Always 80 to 180 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT RELAY (ST RELAY)


    1. Inspect the ST relay Click here.


    NG

    REPLACE RELAY (ST RELAY)

    OK

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


    1. Remove the ST relay from engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      ST relay holder 1 - body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - ST NO. 2 RELAY)


    1. Disconnect the A58 ECM connector.

    2. Disconnect the A92 engine stop and start ECU.

    3. Remove the ST NO. 2 relay from No. 2 engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A92-23 (STA2) - ST NO. 2 relay holder 2 Always Below 1 Ω
      A92-23 (STA2) or ST NO. 2 relay holder 2 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT RELAY (ST NO. 2 RELAY)


    1. Inspect the ST NO. 2 relay Click here.


    NG

    REPLACE RELAY (ST NO. 2 RELAY)

    OK

  8. CHECK HARNESS AND CONNECTOR (ST NO. 2 RELAY - BODY GROUND)


    1. Remove the ST NO. 2 relay from No. 2 engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      ST NO. 2 relay holder 1 - body ground Always Below 1 Ω

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the A90 power management control ECU connector.

    2. Disconnect the A39 clutch start switch assembly connector.

    3. Disconnect the A58 ECM connector. (for 2NR-FKE)

    4. Disconnect the A93 ECM connector. (for 1KR-FE)

    5. Disconnect the A108 ECM connector. (for 1ND-TV)

    6. Disconnect the A92 engine stop and start ECU connector.

    7. Remove the ST relay from engine room relay block.

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

      Standard Resistance
      for 2NR-FKE
      Tester Connection Condition Specified Condition
      A92-21 (STA) - ST relay holder 2 Always Below 1 Ω
      A92-21 (STA), A58-29 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher
      for 1KR-FE
      Tester Connection Condition Specified Condition
      A92-21 (STA) - ST relay holder 2 Always Below 1 Ω
      A92-21 (STA), A93-46 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher
      for 1ND-TV
      Tester Connection Condition Specified Condition
      A92-21 (STA) - ST relay holder 2 Always Below 1 Ω
      A92-21 (STA), A108-53 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - CLUTCH START SWITCH ASSEMBLY)


    1. Disconnect the A90 power management control ECU connector.

    2. Disconnect the A58 ECM connector. (for 2NR-FKE)

    3. Disconnect the A93 ECM connector. (for 1KR-FE)

    4. Disconnect the A108 ECM connector. (for 1ND-TV)

    5. Remove the ST relay from engine room relay block.

    6. Disconnect the A92 engine stop and start ECU connector.

    7. Disconnect the A39 clutch start switch assembly connector.

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

      Standard Resistance
      for 2NR-FKE
      Tester Connection Condition Specified Condition
      A92-21 (STA) - A39-1 Always Below 1 Ω
      A92-21 (STA), A58-29 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher
      for 1KR-FE
      Tester Connection Condition Specified Condition
      A92-21 (STA) - A39-1 Always Below 1 Ω
      A92-21 (STA), A93-46 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher
      for 1ND-TV
      Tester Connection Condition Specified Condition
      A92-21 (STA) - A39-1 Always Below 1 Ω
      A92-21 (STA), A108-53 (STA), A39-1 or ST relay holder 2 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. INSPECT RELAY (ST RELAY)


    1. Inspect the ST relay (for 2NR-FKE) Click here.

    2. Inspect the ST relay (for 1KR-FE) Click here.

    3. Inspect the ST relay (for 1ND-TV) Click here.


    NG

    REPLACE RELAY (ST RELAY)

    OK

  12. CHECK HARNESS AND CONNECTOR (ST RELAY - BODY GROUND)


    1. Remove the ST relay from engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      ST relay holder 1 - body ground Always Below 1 Ω

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR