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.

DTC No. DTC Detection Condition Trouble Area
P1644

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

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 it is warmed up and check that the engine idle speed is within 50 rpm of the target idle speed.


    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.

    4. Start the engine and warm it up.

    5. 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.

    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.

  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 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

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 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.

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.

      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. Disconnect the A36 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the D72 park/neutral position switch assembly connector.

    3. Disconnect the A77 engine stop and start ECU connector.

    4. Remove the ST relay from engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-21 (STA) - ST relay terminal 2 Always Below 1 Ω
      A77-21 (STA) or ST relay terminal 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 ASSEMBLY)


    1. Disconnect the A77 engine stop and start ECU connector.

    2. Disconnect the D72 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
      A77-21 (STA) - D72-9 (L) Always Below 1 Ω
      A77-21 (STA) or D72-9 (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 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

    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 A75 ECM connector.

    2. Disconnect the A77 engine stop and start ECU connector.

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-23 (STA2) - ST NO. 2 relay terminal 2 Always Below 1 Ω
      A77-23 (STA2) or ST NO. 2 relay terminal 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 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 NO. 2 relay terminal 1 - body ground Always Below 1 Ω

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR