DTC C1AFF Brake System Component Performance

DTC detecting condition: 

Correlation between the reaction pressure sensor value and brake pedal stroke sensor value is not normal and this condition continues for a predetermined period of time.

Trouble symptom: 

• Brake cannot be controlled.
• Regenerative brake cannot be controlled.
• Brake assist does not operate.
• EyeSight functions (ACC/PCS) do not operate.

1. CHECK INTERVIEW RESULTS (SYMPTOM OCCURRENCE CONDITION) AND FREEZE FRAME DATA  .
   1. Interview the customer about driving and braking conditions when the brake warning light (red) illuminated.
   2. Using the Subaru Select Monitor, record the following freeze frame data. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>FREEZE FRAME DATA .
      • Shift Position
      • Vehicle Speed
      • Stop Switch
      • Stroke Sensor 1
      • Stroke Sensor 2
      • Reaction Force Pressure
      • Servo Pressure
      • Accumulator Pressure

   Yes:  Go to  2.

   No:  -

2. CHECK BRAKE STROKE SENSOR OUTPUT VOLTAGE VALUE AND BRAKE FLUID PRESSURE  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the brake accumulator assembly connector.
   3. Install a pedal force meter on the brake pedal.
   4. Depress the brake pedal 10 times or more until pedal feel becomes firm.
   5. Install a pressure gauge on brake calipers.
   6. Using Subaru Select Monitor, display [Stroke Sensor 1] in [Data Monitor] of [Electric Brake Booster]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DATA MONITOR .
   7. Operate the brake pedal slowly to check [Stroke Sensor 1] and brake fluid pressure at each pedal force.
      FRONT BRAKE FLUID PRESSURE SPECIFICATION
      
      

      Pedal force [N (kgf)]	[Stroke Sensor 1] [V]	Front brake fluid pressure [MPa (kgf/cm2 )]
      200 (20)	1.14 - 1.84	0.03 (0.3) - 2.03 (20.7)
      500 (51)	1.31 - 2.01	2.00 (20.4) - 4.00 (40.8)

   Is the check result OK?

   Yes:  Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .

   No:  Go to  3.

3. PERFORM LINEAR VALVE OFFSET LEARNING  .
   1. Turn the ignition switch to OFF.
   2. Connect the brake accumulator assembly connector.
   3. Replace the brake stroke sensor.
   4. Using the Subaru Select Monitor, perform [Learning Offset of Liner Solenoid Valve] in [Work Support]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>WORK SUPPORT .

   Yes:  Go to  4.

   No:  -

4. CHECK DTC  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Repeat driving and braking tests based on result from the interview and freeze frame data.
   3. Turn the ignition switch to OFF, and wait for 2 minutes or more.
   4. Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC C1AFF displayed?

   Yes:  Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .

   No:  Finish the diagnosis.