DTC C1C01 Reservoir Level Too Low: Notes

1. - 

DTC detecting condition: 

• When an open circuit condition of the switch signal circuit continues for a predetermined amount of time.
• When a low reservoir level condition continues.

Trouble symptom: 

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

Wiring diagram: 

Electronic controlled brake system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>ELECTRIC CONTROL BRAKE SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is only DTC C1C01 displayed?

   Yes:  Go to  2.

   No:  Perform the diagnosis according to DTC C1C00. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC C1C00 RESERVOIR LEVEL SWITCH CIRCUIT OPEN .

2. CHECK BRAKE FLUID LEAKAGE  .

   Check the brake booster assembly (with master cylinder), brake accumulator assembly, and brake calipers for brake fluid leakage. (Connections, piping)

   Is the check result OK?

   Yes:  Go to  3.

   No:  Repair the brake fluid leakage.

3. AIR BLEEDING FROM BRAKE SYSTEM  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Using the Subaru Select Monitor, perform [Brake System Air Bleeding] of [Brake Air Bleeding] in [Work Support]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>WORK SUPPORT .

   Yes:  Go to  4.

   No:  -

4. CHECK DATA MONITOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the brake stroke sensor connector.
   3. Using Subaru Select Monitor, display [Accumulator Pressure] in [Data Monitor] of [Electric Brake Booster]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DATA MONITOR .
   4. Depress the brake pedal several times so that the pump motor operates, then wait until it stops.
   5. Wait for 30 seconds from the moment the pump motor stops, then check the amount of [Accumulator Pressure] drop and the condition of the pump motor.

   Is the amount of [Accumulator Pressure] drop after 30 seconds less than 2.50 MPa, and does the pump motor fail to start operating within 30 seconds?

   Yes:  Go to  5.

   No:  Repair the brake fluid leakage.

5. CHECK CONNECTOR  .

   Check the connecting condition of the brake fluid sensor connector.

   Is there looseness, deformation, or corrosion at the connectors?

   Yes:  Repair or replace the connector.

   No:  Go to  6.

6. CHECK BRAKE FLUID SENSOR  .
   1. Turn the ignition switch to OFF.
   2. Connect the brake stroke sensor connector.
   3. Disconnect the brake fluid sensor connector.
   4. Measure the resistance between brake fluid sensor terminals.

      Terminals 

      No. 1 - No. 2:

   During Switch OFF (Float up) state, is the resistance within 1.84 - 2.16 kΩ range?

   During Switch ON (Float down) state, is the resistance less than 1 Ω?

   Yes:  Go to  7.

   No:  Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .

7. CHECK CONNECTOR  .

   Check the connecting condition of the EBB control module connector.

   Is there looseness, deformation, or corrosion at the connectors?

   Yes:  Repair or replace the connector.

   No:  Go to  8.

8. CHECK EBB CONTROL MODULE  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the EBB control module connector.
   3. Measure the resistance between EBB control module connector and brake fluid sensor connector and chassis ground.

      Connector & terminal 

      (AD82) No. 23 - (AD83) No. 2: (Resistance: Less than 1 Ω)

      (AD82) No. 23 - Chassis ground: (Resistance: 10 kΩ or more)

      (AD83) No. 1 - Chassis ground: (Resistance: Less than 1 Ω)

   Does the resistance indicate the standard value?

   Yes:  Go to  9.

   No:  Repair or replace the harness.

9. CHECK EBB CONTROL MODULE  .
   1. Connect the EBB control module connector.
   2. Measure the voltage between the brake fluid sensor connector and chassis ground.

      Connector & terminal 

      (AD83) No. 2 (+) - Chassis ground (-):

   Is the voltage 11 - 14 V?

   Yes:  Go to  10.

   No:  Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .

10. RECHECK DTC  .
    1. Turn the ignition switch to OFF.
    2. Connect the brake fluid sensor connector.
    3. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
    4. With READY ON, perform driving and braking tests.
    5. Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC C1C01 displayed?

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

    No:  Currently, it is normal. There may have been a temporary poor contact in the harness and connector or a temporary noise interference.