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):


  • Engine switch on (IG)

  • Malfunction in starter circuit (STA or STA2)


  • Wire harness or connector

  • ST 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 negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 40 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 engine switch on (IG) 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. Depress the brake pedal and stop the vehicle.

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

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

    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 40 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. Depress the brake pedal and stop the vehicle.

    5. Allow the engine to stop by stop and start control. (Keep the shift lever in D.)

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

WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note


  • for 8AR-FTS:

    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

  • for 3ZR-FAE:

    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 engine switch on (IG) 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

  • 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 ECU 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


  • 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 engine switch on (IG).

    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
      DTCs P060B and P1644 are output B
      DTCs P0617 and P1644 are output C
      DTCs P0641 and P1644 are output D

    B
    C
    D
    A
  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - ST RELAY)


    1. Disconnect the A38 engine stop and start ECU connector.

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

    3. Disconnect the I51 certification ECU (smart key ECU assembly) connector.

    4. Disconnect the C14 park/neutral position switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A38-21 (STA) - ST relay terminal 2 Always Below 1 Ω
      A38-21 (STA) - Body ground Always 10 kΩ or higher
      ST relay terminal 2 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

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


    1. Disconnect the A38 engine stop and start ECU connector.

    2. Disconnect the C14 park/neutral position switch assembly connector.

    3. Disconnect the I51 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A38-21 (STA) - C14-9 (L) Always Below 1 Ω
      A38-21 (STA) - Body ground Always 80 to 180 Ω
      C14-9 (L) - Body ground Always 80 to 180 Ω
      Result
      Proceed to
      OK
      NG

    NG
    OK
  4. INSPECT RELAY (ST RELAY)


    1. Inspect the ST relay.


      Result
      Proceed to
      OK
      NG

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


    1. Remove the ST relay from No. 1 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 relay terminal 1 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

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


    1. Disconnect the A38 engine stop and start ECU connector.

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

    3. Disconnect the A35 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A38-23 (STA2) - ST NO. 2 relay terminal 2 Always Below 1 Ω
      A38-23 (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
    OK
  7. INSPECT RELAY (ST NO. 2 RELAY)


    1. Inspect the ST NO. 2 relay.


      Result
      Proceed to
      OK
      NG

    NG
    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 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
    NG