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HOMESERVICE MANUALSSUBARU2022IMPREZA BASE, 4D SEDAN, AUTOMATIC CVT TRANSREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISAUTO START STOP (DIAGNOSTICS)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC P173A: ELECTRIC FLUID PUMP (CVT) STATUS SIGNALNOTES

2022 Subaru Impreza Base, 4D Sedan, Automatic CVT Trans

DTC P173A: Electric Fluid Pump (CVT) Status Signal: Notes

2022 Subaru Impreza Base, 4D Sedan, Automatic CVT TransSECTION Notes

1. -

DTC detecting condition:

Detected when three consecutive driving cycles with fault occur.

Trouble symptom:

Auto Start Stop does not operate.

Wiring diagram:

Auto Start Stop Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>AUTO START STOP .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Use the check board when measuring the TCM terminal voltage and resistance.
After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to AUTO START STOP (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

CHECK REPEATABILITY .
1. Using the Subaru Select Monitor, perform the clear memory of [Auto Start Stop]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
2. Start the engine.
3. Operate Auto Start Stop after driving the vehicle, then restart the engine by pressing the Auto Start Stop cancel switch.
  NOTE:
  Even if Auto Start Stop does not operate, go to step 4).
4. Turn the ignition switch to OFF and wait for 10 seconds.
5. Using the Subaru Select Monitor, read the DTC of [Auto Start Stop] after repeating the procedure from step 2 to 4 three times. Ref. to AUTO START STOP (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is the same DTC as current diagnosis output?

Yes: Go to 2.

No: The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE:
In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK ELECTRIC OIL PUMP OPERATION STATUS SIGNAL .
1. Turn the ignition switch to ON.
2. Read the waveform of electric oil pump operation status signal using an oscilloscope.
  Connector and terminal
  
  (T10) No. 7 (+) - Chassis ground (-):
Is the duty ratio of electric oil pump operation status signal 30%? Ref. to AUTO START STOP (DIAGNOSTICS)>CONTROL MODULE I/O SIGNAL>WAVEFORM .

Yes: Go to 4.

No: Go to 3.
CHECK ELECTRIC OIL PUMP OPERATION COMMAND SIGNAL .
Read the waveform of electric oil pump operation command signal using an oscilloscope.

Connector and terminal

(T10) No. 21 (+) - Chassis ground (-):

Is the duty ratio of electric oil pump operation command signal 10%? Ref. to AUTO START STOP (DIAGNOSTICS)>CONTROL MODULE I/O SIGNAL>WAVEFORM .

Yes: Check for the poor contact in TCM connector and electric oil pump connector. If no fault is found, replace the electric oil pump. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>ELECTRIC FLUID PUMP .

No: Check for the poor contact in TCM connector and electric oil pump connector. Replace the TCM if no fault is found. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>TRANSMISSION CONTROL MODULE (TCM) .
CHECK ELECTRIC OIL PUMP OPERATION STATUS SIGNAL .
1. Start the engine.
2. Perform the active test using Subaru Select Monitor to activate the Auto Start Stop. Ref. to AUTO START STOP (DIAGNOSTICS)>ACTIVE TEST .
3. Read the waveform of electric oil pump operation status signal using an oscilloscope.
  Connector and terminal
  
  (T10) No. 7 (+) - Chassis ground (-):
Is the duty ratio of electric oil pump operation status signal 50%? Ref. to AUTO START STOP (DIAGNOSTICS)>CONTROL MODULE I/O SIGNAL>WAVEFORM .

Yes: Check for poor contact of TCM connector. Replace the TCM if no fault is found. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>TRANSMISSION CONTROL MODULE (TCM) .

No: Go to 5.
CHECK ELECTRIC OIL PUMP OPERATION COMMAND SIGNAL .
1. Start the engine.
2. Perform the active test using Subaru Select Monitor to activate the Auto Start Stop. Ref. to AUTO START STOP (DIAGNOSTICS)>ACTIVE TEST .
3. Read the waveform of electric oil pump operation command signal using an oscilloscope.
  Connector and terminal
  
  (T10) No. 21 (+) - Chassis ground (-):
Is the duty ratio of electric oil pump operation command signal 65%? Ref. to AUTO START STOP (DIAGNOSTICS)>CONTROL MODULE I/O SIGNAL>WAVEFORM .

Yes: Check for the poor contact in TCM connector and electric oil pump connector. If no fault is found, replace the electric oil pump. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>ELECTRIC FLUID PUMP .

No: Check for the poor contact in TCM connector and electric oil pump connector. Replace the TCM if no fault is found. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>TRANSMISSION CONTROL MODULE (TCM) .

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.