DTC P0572 Brake Switch "A" Circuit Low: Notes

1. - 

DTC detecting condition: 

No input state of the EBB control module stop light SW1 signal continues for 10 seconds or more.

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 INSTALLATION POSITION OF STOP LIGHT SWITCH  .

   Check the installation position of the stop light switch. Ref. to BRAKE>STOP LIGHT SWITCH>INSPECTION>INSPECT THE SPECIFIED POSITION .

   Is the check result OK?

   Yes:  Go to  2.

   No:  Adjust the installation position of the stop light switch. Ref. to BRAKE>STOP LIGHT SWITCH .

2. CHECK STOP LIGHT SWITCH UNIT  .

   Perform the inspection of stop light switch unit. Ref. to BRAKE>STOP LIGHT SWITCH>INSPECTION>CHECK OUTPUT .

   Is the check result OK?

   Yes:  Go to  3.

   No:  Replace the stop light switch. Ref. to BRAKE>STOP LIGHT SWITCH .

3. CHECK STOP LIGHT RELAY  .

   Measure the resistance of stop light relay terminals.

   Terminals 

   No. 10 - No. 13:

   Is the resistance less than 1 Ω?

   Yes:  Go to  4.

   No:  Replace the stop light relay. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>RELAY AND FUSE .

4. CHECK CONNECTOR  .
   1. Disconnect the coupling connector. (AD81, B652)
   2. Check the intermediate connector.

      Is there poor contact or damage at the connector?

      Yes:  Repair or replace the intermediate connector.

      No:  Go to  5.

5. CHECK STOP LIGHT SWITCH CIRCUIT (CHECK FOR OPEN CIRCUIT)  .

   Measure the resistance of stop light switch circuit.

   Connector & terminal 

   (B652) No. 17 - (B225) No. 13:

   (B65) No. 2 - (B225) No. 10:

   (B65) No. 1 - (F/B fuse) No. 37:

   Is the resistance less than 1 Ω?

   Yes:  Go to  6.

   No:  Repair the stop light switch circuit.

6. CHECK STOP LIGHT SWITCH CIRCUIT  .
   1. Connect all connectors.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between stop light relay and chassis ground.
      NOTE: When stop lights illuminate (when brake pedal is depressed)

      Connector & terminal 

      (B225) No. 13 (+) - Chassis ground (-):

      Is the voltage 10 V or more?

      Yes:  Go to  7.

      No:  Repair the stop light switch circuit.

7. 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 DTC P0572 displayed?

      Yes:  Go to  8.

      No:  Go to  9.

8. CHECK HARNESS BETWEEN EBB CONTROL MODULE AND INTERMEDIATE CONNECTOR  .
   1. Remove brake booster assembly (with the master cylinder) from vehicle.
   2. Disconnect the EBB control module connector.
   3. Measure the resistance between EBB control module connector and intermediate connector.

      Connector & terminal 

      (AD82) No. 20 - (AD81) No. 17:

      Is the resistance less than 1 Ω?

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

      No:  Repair or replace the harness.

9. CHECK DETECTION OF OTHER DTCS FOR EBB CONTROL MODULE  .

   Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is any other DTC displayed?

   Yes:  Perform the diagnosis according to the DTC. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

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