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 mechanical oil pump of the continuously variable 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 with motor assembly is operated continuously ensuring optimal CVT oil pressure and smooth start-off when the engine is restarted.

The engine stop and start ECU supplies power to the oil pump with motor assembly via terminal OPO and operates the oil pump with motor assembly in accordance with signals sent from terminal OPM1.

The oil pump with motor assembly sends status signals to the engine stop and start ECU via the NOPM signal line.

DTC No. Freeze Frame Data * DTC Detection Condition Trouble Area
P1538 O/P Circuit/Relay Error

The following condition continues for 2 seconds or more (1 trip detection logic):


  1. 0.5 seconds after ECU internal oil pump motor relay turns ON.

  2. NOPM signal wire open circuit or shorted to +B, or ECU internal oil pump motor relay is OFF.

  • Wire harness or connector

  • Engine stop and start ECU

  • Oil pump with motor assembly
O/P Signal GND Short

The following condition continues for 2 seconds or more (1 trip detection logic):


  1. 0.5 seconds after ECU internal oil pump motor relay turns ON.

  2. Short to ground in NOPM signal line.
O/P Signal Open/ Short

The following condition continues for 2 seconds or more (1 trip detection logic):


  1. 0.5 seconds after ECU internal oil pump motor relay turns ON.

  2. OPM1 signal wire open circuit, shorted to +B, or shorted to GND.
O/P Relay Malfunction

The following condition continues for 2 seconds or more (1 trip detection logic):


  1. 0.5 seconds after ECU internal oil pump motor relay turns ON.

  2. NOPM signal wire is normal, and ECU internal oil pump motor relay is ON.

*: 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. After troubleshooting, perform the following steps to recheck for DTCs and check if the stop and start system operates normally.

    Tech Tips


    • If the cable is disconnected from the battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item Status of Battery Charge Control changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery temperature at 11°C (52°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item Status of Battery Charge Control cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates. If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.

    • 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 ignition switch to ON 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. Check if the stop and start system operates normally.

    Tech Tips


    • If the cable is disconnected from the battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item Status of Battery Charge Control changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery temperature at 11°C (52°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item Status of Battery Charge Control cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates. If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.


    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

A00497WE10
*a OPO
*b NOPM
*c Oil Pump with Motor Assembly
*d 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 with motor assembly after removing and installing the continuously variable transaxle assembly or replacing the CVT 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 ignition switch to ON.

    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
      Freeze Frame Data Item Proceed to
      "O/P Circuit/Relay Error" is ON A
      "O/P Signal GND Short" is ON B
      "O/P Signal Open/Short" is ON C
      "O/P Relay Malfunction" is ON D

    B

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

    C

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

    D

    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 CVT fluid.

      Note

      The oil pump with motor assembly may not operate properly if the CVT fluid temperature is low. Make sure to warm up the CVT fluid before performing the Active Test. (CVT fluid temperature: 30°C (86°F) or higher).

    2. Stop the engine.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON.

      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 with motor 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 ENGINE STOP AND START ECU (OPO TERMINAL VOLTAGE) Click here

    OK

  3. CHECK WAVEFORM (NOPM TERMINAL WAVEFORM)


    1. Drive the vehicle to warm up the engine and CVT fluid.

      Note

      The oil pump with motor assembly may not operate properly if the CVT fluid temperature is low. Make sure to warm up the CVT fluid before performing the Active Test. (CVT fluid temperature: 30°C (86°F) or higher).

    2. Stop the engine.

    3. Connect an oscilloscope to terminals A92-27 (NOPM) and A91-8 (GND).

      A004ALWE03
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    4. Connect the GTS to the DLC3.

    5. Turn the ignition switch to ON.

      Tech Tips

      Do not start the engine.

    6. Turn the GTS on.

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

    8. A0047TUE07

      Check the waveform while performing the Active Test.

      Item Condition
      Tester Connection A92-27 (NOPM) - A91-8 (GND)
      Tool Setting 5 V/DIV., 5 ms./DIV.
      Condition

      • Turn the ignition switch to ON (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 WITH MOTOR ASSEMBLY (OPST TERMINAL VOLTAGE)


    1. A0049MQE02
      Text In Illustration
      *a

      Front view of wire harness connector

      (to oil pump with motor assembly)

      Disconnect the oil pump with motor assembly connector

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      B113-3 (OPST) - B113-4 (GND) Ignition switch ON 8 to 14 V
      Result
      Result Proceed to
      NG A
      OK B

    B

    REPLACE OIL PUMP WITH MOTOR ASSEMBLY Click here

    A

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


    1. Disconnect the A92 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A92-27 (NOPM) - B113-3 (OPST) Always Below 1 Ω
      A92-27 (NOPM) or B113-3 (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 ENGINE STOP AND START ECU (OPO TERMINAL VOLTAGE)


    1. Drive the vehicle to warm up the engine and CVT fluid.

      Note

      The oil pump with motor assembly may not operate properly if the CVT fluid temperature is low. Make sure to warm up the CVT fluid before performing the Active Test. (CVT fluid temperature: 30°C (86°F) or higher).

    2. Stop the engine.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON.

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

      A0047WIE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      A91-6 (OPO) - A91-8 (GND)

      • Turn the ignition switch to ON (engine is stopped)

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

      		 10 to 14 V

    NG

    CHECK ENGINE STOP AND START ECU (CHECK FOR SHORT IN WIRE HARNESS) Click here

    OK

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


    1. Disconnect the A92 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A91-6 (OPO) - B113-1 (+B) Always Below 1 Ω
      A91-6 (OPO) or B113-1 (+B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (OIL PUMP WITH MOTOR ASSEMBLY - BODY GROUND)


    1. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B113-4 (GND) - Body ground Always Below 1 Ω

    OK

    REPLACE OIL PUMP WITH MOTOR ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. CHECK ENGINE STOP AND START ECU (CHECK FOR SHORT IN WIRE HARNESS)


    1. Drive the vehicle to warm up the engine and CVT fluid.

      Note

      The oil pump with motor assembly may not operate properly if the CVT fluid temperature is low. Make sure to warm up the CVT fluid before performing the Active Test. (CVT fluid temperature: 30°C (86°F) or higher).

    2. Stop the engine.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON.

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

      A0047WIE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      A91-6 (OPO) - A91-8 (GND)

      • Turn the ignition switch to ON (engine is stopped)

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

      		 10 to 14 V
      Result
      Result Proceed to
      NG A
      OK B

    B

    REPLACE OIL PUMP WITH MOTOR ASSEMBLY Click here

    A

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


    1. Disconnect the A91 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B113-1 (+B) - A91-6 (OPO) Always Below 1 Ω
      B113-1 (+B) or A91-6 (OPO) - Body ground Always 10 kΩ or higher

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the A92 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B113-3 (OPST) - A92-27 (NOPM) Always Below 1 Ω
      B113-3 (OPST) or A92-27 (NOPM) - 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 B113 oil pump with motor assembly connector.

      A004ALWE04
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    2. Turn the ignition switch ON.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A92-27 (NOPM) - A91-8 (GND) Turn the ignition switch to ON 10 to 14 V

    OK

    REPLACE OIL PUMP WITH MOTOR ASSEMBLY Click here

    NG

    REPLACE ENGINE STOP AND START ECU Click here

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


    1. Disconnect the A92 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A92-9 (OPM1) - B113-2 (SI) Always Below 1 Ω
      A92-9 (OPM1) or B113-2 (SI) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  14. CHECK WAVEFORM (OPM1 TERMINAL WAVEFORM)


    1. Drive the vehicle to warm up the engine and CVT fluid.

      Note

      The oil pump with motor assembly may not operate properly if the CVT fluid temperature is low. Make sure to warm up the CVT fluid before performing the Active Test. (CVT fluid temperature: 30°C (86°F) or higher).

    2. Stop the engine.

    3. Connect an oscilloscope to terminals A92-9 (OPM1) and A91-8 (GND).

      A004BKTE02
      Text In Illustration
      *a

      Component with harness connected

      (Engine stop and start ECU)

      		 - -

    4. Connect the GTS to the DLC3.

    5. Turn the ignition switch to ON.

      Tech Tips

      Do not start the engine.

    6. Turn the GTS on.

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

    8. A004AGME03

      Check the waveform while performing the Active Test.

      Item Condition
      Tester Connection A92-9 (OPM1) - A91-8 (GND)
      Tool Setting 5 V/DIV., 5 ms./DIV.
      Condition

      • Turn the ignition switch to ON (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 WITH MOTOR ASSEMBLY Click here

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


    1. Disconnect the A92 engine stop and start ECU connector.

    2. Disconnect the B113 oil pump with motor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A91-6 (OPO) - B113-1 (+B) Always Below 1 Ω
      A91-6 (OPO) or B113-1 (+B) - Body ground Always 10 kΩ or higher

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR