STOP AND START SYSTEM, Diagnostic DTC:P1538

DTC Code DTC Name
P1538 Circuit Malfunction between AT Oil Pump and Stop and Start ECU

DESCRIPTION

The oil pump of the automatic transaxle assembly stops operating when the engine is stopped by stop and start control. While the engine is stopped by stop and start control, the oil pump assembly with motor (automatic transaxle assembly) is operated continuously ensuring optimal automatic transaxle oil pressure and smooth start-off when the engine is restarted.

The engine stop and start ECU supplies power to the oil pump assembly with motor (automatic transaxle assembly) via terminal OP21 and operates the oil pump assembly with motor (automatic transaxle assembly) in accordance with signals sent from terminal OPM1. The oil pump assembly with motor (automatic transaxle assembly) sends operating speed signals to the engine stop and start ECU via the NOPM signal line.

DTC No. Freeze Frame Data * DTC Detection Condition Trouble Area
P1538 Status of O/P Signal 1

Both of the following conditions are met for 2 seconds or more

(1 trip detection logic):


  • Oil pump motor relay circuit in the engine stop and start ECU is off

  • Oil pump assembly with motor (automatic transaxle assembly) power supply malfunction (Oil pump motor relay circuit in the engine stop and start ECU stuck on or shorted) or a short to ground in the NOPM circuit

  • Wire harness or connector

  • Engine stop and start ECU

  • Oil pump assembly with motor (automatic transaxle assembly)
Status of O/P Signal 2

Both of the following conditions are met for 1 second or more

(2 trip detection logic):


  • Engine started

  • Oil pump assembly with motor (automatic transaxle assembly) circuit malfunction (Oil pump motor relay in the engine stop and start ECU stuck off, open or short to ground in the OP21, OPM1 or NOPM circuit or an open in the GND circuit)

*: Since each information can be confirmed by freeze frame data, record the freeze frame data before deleting the diagnosis code.

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 Click here.

    3. Clear the DTCs.

    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. Keep the engine stopped 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 no DTCs are 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

A01W2B7E08
*a NOPM
*b Oil Pump Assembly with Motor (Automatic Transmission Assembly)
*c Engine Stop and Start ECU

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.

  • Bleed the oil pump assembly with motor (automatic transaxle assembly) after removing and installing the automatic transaxle assembly or replacing the automatic transaxle fluid Click here.

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.

PROCEDURE


  1. CHECK FREEZE FRAME DATA

    Note

    The freeze frame data is cleared when DTCs are cleared. Be sure to make a note of necessary data in advance.


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. According to the display on the GTS, select DTC P1538 and check the sets of freeze frame data. Click here.

      Result
      GTS Display Result Proceed to
      Status of O/P Signal 1 Abnormal B
      Status of O/P Signal 2 Abnormal A

    B

    CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP WITH MOTOR ASSEMBLY) Click here

    A

  2. PERFORM ACTIVE TEST USING GTS (AT OIL PUMP (LO))


    1. Drive the vehicle to warm up the engine and automatic transaxle fluid.

      Note

      The oil pump assembly with motor (automatic transaxle assembly) may not operate properly if the automatic transaxle fluid temperature is low. Make sure to warm up the automatic transaxle fluid before performing the Active Test. (automatic transaxle fluid temperature: 25°C (77°F) or higher).

    2. Turn the engine switch off.

    3. Connect the GTS to the DLC3.

    4. Turn the engine switch on (IG).

      Tech Tips

      Do not start the engine.

    5. Turn the GTS on.

    6. Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

    7. Check the operating sound of the oil pump assembly with motor (automatic transaxle assembly) while performing the Active Test.

      Standard
      AT Oil Pump (Lo) Operating sound and vibration
      ON Operating sound can be heard
      OFF Operating sound cannot be heard

    NG

    CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY)) Click here

    OK

  3. CHECK WAVEFORM (NOPM TERMINAL WAVEFORM)


    1. Connect an oscilloscope to terminals A77-27 (NOPM) and A77-6 (DGND).

      A01VZQXE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    2. Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

    3. A01VZVSE09
      *a 5 V/DIV.
      *b 5 ms./DIV.

      Check the waveform while performing the Active Test.

      Item Condition
      Tester Connection A77-27 (NOPM) - A77-6 (DGND)
      Tool Setting 5 V/DIV., 5 ms./DIV.
      Condition

      • Turn the engine switch on (IG) (engine is stopped)

      • Active Test "AT Oil Pump (Lo)" being performed
      Standard
      The waveform is similar to that shown in the illustration with no noise.
      Result
      Result Proceed to
      NG A
      OK B

    B

    REPLACE ENGINE STOP AND START ECU Click here

    A

  4. CHECK OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) (OPST TERMINAL VOLTAGE)


    1. A01W2EIE02
      Text In Illustration
      *a

      Front view of wire harness connector

      (to oil pump motor assembly with motor)

      Disconnect D94 the oil pump assembly with motor (automatic transaxle assembly) connector.

    2. Turn the engine switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D94-2 (OPST) - D94-1 (GND) Engine switch on (IG) 10 to 14 V
      Result
      Result Proceed to
      NG A
      OK B

    B

    REPLACE OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) Click here

    A

  5. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY)


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

    2. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-27 (NOPM) - D94-2 (OPST) Always Below 1 Ω
      A77-27 (NOPM) or D94-2 (OPST) - Body ground Always 10 kΩ or higher

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY))


    1. Disconnect the A76 engine stop and start ECU connector.

    2. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A76-6 (OP21) - D94-4 (+B) Always Below 1 Ω
      A76-6 (OP21) or D94-4 (+B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) - BODY GROUND)


    1. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D94-1 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK ENGINE STOP AND START ECU (OP21 TERMINAL VOLTAGE)


    1. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

    2. Connect the GTS to the DLC3.

    3. Turn the engine switch on (IG).

      Tech Tips

      Do not start the engine.

    4. Turn the GTS on.

    5. Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

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

      A01W3FSE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      A76-6 (OP21) - A77-6 (DGND)

      • Turn the engine switch on (IG) (engine is stopped)

      • Active Test "AT Oil Pump (Lo)" being performed

      		 10.5 to 16 V

    NG

    REPLACE ENGINE STOP AND START ECU Click here

    OK

  9. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY))


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

    2. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-9 (OPM1) - D94-3 (SI) Always Below 1 Ω
      A77-9 (OPM1) or D94-3 (SI) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) (OPM1 TERMINAL WAVEFORM)


    1. Connect an oscilloscope to terminals A77-9 (OPM1) and A77-6 (DGND).

      A01W0DDE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    2. Connect the GTS to the DLC3.

    3. Turn the engine switch on (IG).

      Tech Tips

      Do not start the engine.

    4. Turn the GTS on.

    5. Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

    6. A01W2CPE04
      *a 5 V/DIV.
      *b 5 ms./DIV.

      Check the waveform while performing the Active Test.

      Item Condition
      Tester Connection A77-9 (OPM1) - A77-6 (DGND)
      Tool Setting 5 V/DIV., 5 ms./DIV.
      Condition

      • Turn the engine switch on (IG) (engine is stopped)

      • Active Test "AT Oil Pump (Lo)" being performed
      Standard
      The waveform is similar to that shown in the illustration with no noise.

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPLACE OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) Click here

  11. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - OIL PUMP WITH MOTOR ASSEMBLY)


    1. Disconnect the A77 and A76 engine stop and start ECU connectors.

    2. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-27 (NOPM) - D94-2 (OPST) Always Below 1 Ω
      A76-6 (OP21) - D94-4 (+B) Always Below 1 Ω
      A77-27 (NOPM) - Body ground Always 10 kΩ or higher
      D94-2 (OPST) - Body ground Always 10 kΩ or higher
      A76-6 (OP21) - Body ground Always 10 kΩ or higher
      D94-4 (+B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. CHECK ENGINE STOP AND START ECU (NOPM TERMINAL VOLTAGE)


    1. Disconnect the D94 oil pump assembly with motor (automatic transaxle assembly) connector.

      A01VZQXE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    2. Turn the engine switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A77-27 (NOPM) - A77-6 (DGND) Engine switch on (IG) 10 to 14 V

    OK

    REPLACE OIL PUMP ASSEMBLY WITH MOTOR (AUTOMATIC TRANSAXLE ASSEMBLY) Click here

    NG

    REPLACE ENGINE STOP AND START ECU Click here