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. Detection Item DTC Detection Condition Trouble Area Warning Indicate Memory
P1644 ECU Internal Error

Both of the following conditions are met for 0.2 seconds or more (1 trip detection logic):


  • Ignition switch ON

  • Malfunction in starter circuit (STA or STA2)

  • Wire harness or connector

  • ST NO. 1 relay

  • ST NO. 2 relay

  • Engine stop and start ECU

 Blinks 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. 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 with the battery temperature at 11°C (51°F) or higher for 5 to 60 minutes 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".)

    • 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 engine 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 the engine warms up and check that the engine 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 (12.4 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    6. for Automatic Transmission:

      Depress the brake pedal and stop the vehicle.

      for Manual Transmission:

      Stop the vehicle, move the shift lever to neutral and release the clutch pedal.

    7. Allow the engine to stop by stop and start control. (for Automatic Transmission: Keep the shift lever in D.)

    8. for Automatic Transmission:

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

      for Manual Transmission:

      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 the battery voltage is low.

    9. Check that DTCs are not output.

      Click here


      Powertrain > Stop and Start > Trouble Codes

  2. 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 with the battery temperature at 11°C (51°F) or higher for 5 to 60 minutes 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".)

    • 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 engine 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.

    STOP AND START SYSTEM OPERATION CHECK


    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 Automatic Transmission:

      Depress the brake pedal and stop the vehicle.

      for Manual Transmission:

      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 Automatic Transmission: Keep the shift lever in D.)

    6. for Automatic Transmission:

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

      for Manual Transmission:

      Depress the clutch pedal and start the engine.

WIRING DIAGRAM

Click here

CAUTION / NOTICE / HINT

Note


  • Before replacing the engine stop and start ECU, read the number of starter operations and total number of engine starts 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

  • for Automatic Transmission:

    When the engine stop and start ECU is replaced, check the electromagnetic oil pump.

    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

  • 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.

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. Read the DTCs.


      Powertrain > Stop and Start > Trouble Codes
      Result
      Result Proceed to
      DTC P1644 is output A
      DTC P060B and P1644 are output B
      DTC P0617 and P1644 are output C

    B

    GO TO DTC P060B Click here

    C

    GO TO DTC P0617 Click here

    A

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - ST NO. 1 RELAY)


    1. Disconnect the G126 engine stop and start ECU connector.

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

    3. w/ Entry and Start System:

      Disconnect the G70 certification ECU (smart key ECU assembly) connector.

    4. for Automatic Transmission:

      Disconnect the C24 park/neutral position switch assembly connector.

    5. for Manual Transmission:

      Disconnect the B2 clutch start switch assembly (for lower) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G126-21 (STA) - ST NO. 1 relay terminal 2 Always Below 1 Ω
      G126-21 (STA) - Body ground Always 10 kΩ or higher
      ST NO. 1 relay terminal 2 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the G126 engine stop and start ECU connector.

    2. for Automatic Transmission:

      Disconnect the C24 park/neutral position switch assembly connector.

    3. for Manual Transmission:

      Disconnect the B2 clutch start switch assembly (for lower) connector.

    4. w/ Entry and Start System:

      Disconnect the G70 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      for Automatic Transmission:
      Tester Connection Condition Specified Condition
      G126-21 (STA) - C24-5 (L) Always Below 1 Ω
      G126-21 (STA) - Body ground Always 80 to 180 Ω
      C24-5 (L) - Body ground Always 80 to 180 Ω
      for Manual Transmission:
      Tester Connection Condition Specified Condition
      G126-21 (STA) - B2-1 Always Below 1 Ω
      G126-21 (STA) - Body ground Always 80 to 180 Ω
      B2-1 - Body ground Always 80 to 180 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT RELAY (ST NO. 1 RELAY)


    1. Inspect the ST NO. 1 relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (ST NO. 1 RELAY)

    OK

  5. CHECK HARNESS AND CONNECTOR (ST NO. 1 RELAY - BODY GROUND)


    1. Remove the ST NO. 1 relay from the engine room relay block and junction block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 1 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    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 G126 engine stop and start ECU connector.

    2. Remove the ST NO. 2 relay from the engine room relay block and junction block.

    3. Disconnect the G85 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G126-23 (STA2) - ST NO. 2 relay terminal 2 Always Below 1 Ω
      G126-23 (STA2) - Body ground Always 10 kΩ or higher
      ST NO. 2 relay terminal 2 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT RELAY (ST NO. 2 RELAY)


    1. Inspect the ST NO. 2 relay.

      Click here

      Result
      Proceed to
      OK
      NG

    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 the engine room relay block and junction 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 terminal 1 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR