STOP AND START SYSTEM(for 2WW), 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

The following condition continues for 0.2 seconds or more (1 trip detection logic):


  • Ignition switch ON

  • Malfunction in starter circuit (STA)

  • Wire harness or connector

  • ST 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. 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 (12.4 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. Allow the engine to stop by stop and start control.

    8. Depress the clutch pedal and 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 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

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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, perform deceleration sensor zero point clear and calibration.

    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.

  • If DTCs P0617 and P1644 are output simultaneously, perform troubleshooting for DTC P0617 (Starter Relay Circuit High) 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. Read the DTCs.


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


    1. w/ Entry and Start System:

      Disconnect the G82 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the A66 engine stop and start ECU connector.

    3. Disconnect the A62 ECM connector.

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

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A66-21 (STA) - ST relay terminal 2 Always Below 1 Ω
      A66-21 (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

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. w/ Entry and Start System:

      Disconnect the G82 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the A66 engine stop and start ECU connector.

    3. Disconnect the A4*1 or F2*2 clutch start switch assembly (for lower) connector.


      • *1: for LHD

      • *2: for RHD

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

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

      Standard Resistance
      for LHD:
      Tester Connection Condition Specified Condition
      A66-21 (STA) - A4-1 Always Below 1 Ω
      A66-21 (STA) - Body ground Always 80 Ω to 180 Ω
      A4-1 - Body ground Always 80 Ω to 180 Ω
      for RHD:
      Tester Connection Condition Specified Condition
      A66-21 (STA) - F2-1 Always Below 1 Ω
      A66-21 (STA) - Body ground Always 80 Ω to 180 Ω
      F2-1 - Body ground Always 80 Ω to 180 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT RELAY (ST RELAY)


    1. Inspect the ST relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (ST RELAY)

    OK

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


    1. Remove the ST relay from the No. 2 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
      ST 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