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

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

  • Malfunction in the engine stop and start ECU internal drive circuit for the starter assembly.

  • Wire harness or connector

  • ST relay

  • Engine stop and start ECU

CONFIRMATION DRIVING PATTERN

Tip:

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

    Tip:

    • When the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited for a certain amount of time. After connecting the cable, drive the vehicle until stop and start control is permitted (approximately 15 to 40 minutes).

    • 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).

    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).

  2. STOP AND START SYSTEM OPERATION CHECK

    Tip:

    When the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited for a certain amount of time. After connecting the cable, drive the vehicle until stop and start control is permitted (approximately 15 to 40 minutes).

    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

Refer to DTC 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 yaw rate sensor, perform deceleration sensor zero point clear and calibration (Click here).

  • Inspect the fuses for circuits related to this system before performing the following procedure.

Tip:

  • 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.

  • 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.

      Table 1. 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

      DTC P0641 and DTC P1644 are output

      D

    GO TO DTC P060B

    (Click here)

    GO TO DTC P0617

    (Click here)

    GO TO DTC P0641

    (Click here)

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

    Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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

    Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  4. INSPECT RELAY (ST RELAY)

    1. Inspect the ST relay (Click here).

    REPLACE RELAY (ST RELAY)

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

    Click here

    REPLACE ENGINE STOP AND START ECU

    (Click here)

    REPAIR OR REPLACE HARNESS OR CONNECTOR