STOP AND START SYSTEM(for 3ZR-FAE), 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 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 assembly with motor 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 assembly via terminal OP21 and operates the oil pump assembly with motor in accordance with signals sent from terminal OPM1. The oil pump assembly with motor sends operating speed signals to the engine stop and start ECU via the NOPM signal line.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Memory
P1538	Circuit Malfunction between AT Oil Pump and Stop and Start ECU	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 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 circuit1 Both of the following conditions are met for 1 second or more (2 trip detection logic): Engine started Oil pump assembly with motor 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)2	Wire harness or connector Oil pump assembly with motor (Continuously variable transaxle assembly) Engine stop and start ECU	Blinks	DTC stored

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Memory

P1538

Circuit Malfunction between AT Oil Pump and Stop and Start ECU

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 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*1

Both of the following conditions are met for 1 second or more (2 trip detection logic):

Engine started
Oil pump assembly with motor 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)*2

Wire harness or connector
Oil pump assembly with motor (Continuously variable transaxle assembly)
Engine stop and start ECU

Blinks

DTC stored

*1: "Abnormal" is displayed for the freeze frame data item [Status of O/P Signal 1]

*2: "Abnormal" is displayed for the freeze frame data item [Status of O/P Signal 2]

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

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 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 (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
  
  Powertrain > Stop and Start > Trouble Codes
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


*a	NOPM
*b	Engine Stop and Start ECU
*c	Oil Pump Assembly with Motor (Continuously Variable Transaxle Assembly)

CAUTION / NOTICE / HINT

Note

When replacing the engine stop and start ECU with a new one, make sure to download the previous status (number of starter operations) of the old engine stop and start ECU. After replacing the engine stop and start ECU, turn the ignition switch to ON and wait 20 seconds, then confirm that "OK" is displayed for the Data List item "Oper Prohibition (O/P Air Bleeding)". Then upload the previous status (number of starter operations) to the 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 (continuously variable transaxle 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

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.

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

Click here

Result

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

PERFORM ACTIVE TEST USING GTS (AT OIL PUMP (LO)) Click here

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

Disconnect the A86 and A66 engine stop and start ECU connectors.
Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A66-27 (NOPM) - B92-2 (OPST)	Always	Below 1 Ω
A86-6 (OP21) - B92-4 (+B)	Always	Below 1 Ω
A66-27 (NOPM) - Body ground	Always	10 kΩ or higher
B92-2 (OPST) - Body ground	Always	10 kΩ or higher
A86-6 (OP21) - Body ground	Always	10 kΩ or higher
B92-4 (+B) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK ENGINE STOP AND START ECU (NOPM TERMINAL VOLTAGE)

Component with harness connected

(Engine Stop and Start ECU)

Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.
Turn the ignition switch to ON.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A66-27 (NOPM) - A66-6 (DGND)	Ignition switch ON	10 to 14 V

Result

Proceed to
OK
NG

REPLACE CONTINUOUSLY VARIABLE TRANSAXLE ASSEMBLY Click here

REPLACE ENGINE STOP AND START ECU Click here

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

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

Tech Tips

The oil pump assembly with motor (continuously variable transaxle 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: 25°C (77°F) or higher)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.

Tech Tips

Do not start the engine.
Turn the GTS on.
Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

Powertrain > Stop and Start > Active Test

Tester Display

AT Oil Pump (Lo)

Tester Display
AT Oil Pump (Lo)

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

Standard

AT Oil Pump (Lo)	Result
ON	Operating sound can be heard
OFF	Operating sound cannot be heard

Result

Proceed to
OK
NG

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

CHECK ENGINE STOP AND START ECU (NOPM TERMINAL WAVEFORM)

Connect an oscilloscope to the A66-27 (NOPM) and A66-6 (DGND) terminals of the engine stop and start ECU connector.
Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

Powertrain > Stop and Start > Active Test

Tester Display

AT Oil Pump (Lo)

Tester Display
AT Oil Pump (Lo)


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

Check the waveform while performing the Active Test.

Item	Condition
Tester Connection	A66-27 (NOPM) - A66-6 (DGND)
Tool Setting	5 V/DIV., 5 ms./DIV.
Condition	Ignition switch 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

Proceed to
OK
NG

REPLACE ENGINE STOP AND START ECU Click here

CHECK OIL PUMP ASSEMBLY WITH MOTOR (OPST TERMINAL VOLTAGE)

*a
Front view of wire harness connector

(to Oil Pump Assembly with Motor (Continuously Variable Transaxle Assembly))

Disconnect the oil pump assembly with motor (continuously variable transaxle assembly) connector.
Turn the ignition switch to ON.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
B92-2 (OPST) - B92-1 (GND)	Ignition switch ON	10 to 14 V

Result

Proceed to
OK
NG

REPLACE CONTINUOUSLY VARIABLE TRANSAXLE ASSEMBLY Click here

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

Disconnect the A66 engine stop and start ECU connector.
Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A66-27 (NOPM) - B92-2 (OPST)	Always	Below 1 Ω
A66-27 (NOPM) - Body ground	Always	10 kΩ or higher
B92-2 (OPST) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPLACE ENGINE STOP AND START ECU Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Disconnect the A86 engine stop and start ECU connector.
Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A86-6 (OP21) - B92-4 (+B)	Always	Below 1 Ω
A86-6 (OP21) - Body ground	Always	10 kΩ or higher
B92-4 (+B) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B92-1 (GND) - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK ENGINE STOP AND START ECU (OP21 TERMINAL VOLTAGE)

Component with harness connected

(Engine Stop and Start ECU)

Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.
Connect the GTS to the DLC3.
Turn the ignition switch to ON.

Tech Tips

Do not start the engine.
Turn the GTS on.
Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

Powertrain > Stop and Start > Active Test

Tester Display

AT Oil Pump (Lo)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A86-6 (OP21) - A66-6 (DGND)	Ignition switch ON (engine is stopped) Active Test "AT Oil Pump (Lo)" being performed	10.5 to 16 V

Result

Proceed to
OK
NG

REPLACE ENGINE STOP AND START ECU Click here

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

Disconnect the A66 engine stop and start ECU connector.
Disconnect the B92 oil pump assembly with motor (continuously variable transaxle assembly) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A66-9 (OPM1) - B92-3 (SI)	Always	Below 1 Ω
A66-9 (OPM1) - Body ground	Always	10 kΩ or higher
B92-3 (SI) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK OIL PUMP ASSEMBLY WITH MOTOR (OPM1 TERMINAL WAVEFORM)

Connect an oscilloscope to the A60-9 (OPM1) and A60-6 (DGND) terminals of the engine stop and start ECU connector.
Connect the GTS to the DLC3.
Turn the ignition switch to ON.

Tech Tips

Do not start the engine.
Turn the GTS on.
Enter the following menus: Powertrain / Stop and Start / Active Test / AT Oil Pump (Lo).

Powertrain > Stop and Start > Active Test

Tester Display

AT Oil Pump (Lo)


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

Check the waveform while performing the Active Test.

Item	Condition
Tester Connection	A66-9 (OPM1) - A66-6 (DGND)
Tool Setting	5 V/DIV., 5 ms./DIV.
Condition	Ignition switch 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

Proceed to
OK
NG

REPLACE ENGINE STOP AND START ECU Click here

REPLACE CONTINUOUSLY VARIABLE TRANSAXLE ASSEMBLY Click here