LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2017 >> BRZ Limited, Automatic Trans >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transaxle (Diagnostics) >> Automatic transmission system >> DTC P0973, P0974: Shift Solenoid "A" Control Circuit Low, Shift Solenoid "A" Control Circuit High >> Notes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0973, P0974: Shift Solenoid "A" Control Circuit Low, Shift Solenoid "A" Control Circuit High: Notes

Circuit description

Signals from the transmission control computer ASSY change the vehicle speed from 1st to 6th gear according to the combination of the transmission 3 way solenoid ASSY (S1, S2, S3, S4, SR) and the clutch control solenoid No. 1 (SL1, SL2). When there is an open or short circuit in the solenoid valve system, the transmission control computer ASSY stops continuity to all solenoids as the fail safe function. As a result, only the mechanical hydraulic circuit is available and the manual shift control is initiated.

DTC No. SAE/TCCS DTC detecting condition
  1. Diagnosis condition
  2. Abnormal condition
  3. Abnormal period
  4. Other
Inspection parts
P0973
  1. Learning control is not prohibited.
  2. When transmission 3 way solenoid ASSY (S1) ON is output, transmission control computer ASSY S1 output monitor value is OFF.
  3. 500 ms or more durations
  4. trips
  • Transmission 3 way solenoid ASSY (S1)
  • Transmission wire
  • Wiring harness or connector
  • Transmission control computer ASSY
P0974
  1. Learning control is not prohibited.
  2. When transmission 3 way solenoid ASSY (S1) OFF is output, transmission control computer ASSY S1 output monitor value is ON.
  3. 500 ms or more durations
  4. trips
  • Transmission 3 way solenoid ASSY (S1)
  • Transmission wire
  • Wiring harness or connector
  • Transmission control computer ASSY

Monitor description

These diagnostic codes indicate open or short circuit in the transmission 3 way solenoid ASSY (S1) circuit. If there is open or short circuit in any of the shift solenoid valve circuits, TCM detects the defect, turns on MIL, and records the diagnostic code.

MONITOR STRATEGY DESCRIPTION

Applicable diagnostic codes P0973: Shift Solenoid "A" Control Circuit Low
P0974: Shift Solenoid "A" Control Circuit High
Required sensor/component Transmission 3 way solenoid ASSY (S1)
Operation frequency Consecutive
Period 0.5 seconds
MIL operation Immediate
Operation order None
TYPICAL ENABLING CONDITIONS DESCRIPTION

Battery voltage 10.2 V or more
Above condition is established 2 seconds or more
Fail safe mode (solenoid power supply shut down) Non-active

TYPICAL MALFUNCTION THRESHOLDS

TYPICAL MALFUNCTION THRESHOLDS DESCRIPTION

Output monitor status when TCM outputs ON signal OFF
TYPICAL MALFUNCTION THRESHOLDS DESCRIPTION

Output monitor status when TCM outputs OFF signal ON