DTC C12F8-12: ECB Solenoid Control "A" Circuit Short to Battery; DTC C12F8-14: ECB Solenoid Control "A" Circuit Short to Ground or Open [11/2020 - ]: Procedure

1. Perform the Active Test and operate the main relay.
2. Monitor the value of BS Voltage when the Active Test is being performed.

   Chassis > Brake Booster > Active Test 

   Tester Display	Measurement Item	Control Range	Restrict Condition	Diagnostic Note
   ECB Main Relay	Main relay	OFF / ON	Vehicle condition: Vehicle stopped HINT:  To protect this Actuator and Solenoid, this test will only last 5 seconds.	ECB: Electronically Controlled Brake System

   Chassis > Brake Booster > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   BS Voltage	BS voltage value	Min.: 0.0 V Max.: 25.5 V	-	Changes in proportion to auxiliary battery voltage

   Chassis > Brake Booster > Active Test 

   Active Test Display
   ECB Main Relay

   Data List Display
   BS Voltage

   HINT: 

   During the Active Test, the voltage indicated by BS Voltage changes in proportion to the voltage of the auxiliary battery.

   Result

   Result	Proceed to
   During the Active Test, the voltage indicated by BS Voltage increases to the approximate voltage of the auxiliary battery.	A
   During the Active Test, the voltage indicated by BS Voltage remains low around 0 V.	B

Result: 

B 

See step  4

Result: 

A 

See step  2

Pre-procedure1

• None

• Clear the DTCs.

  Chassis > Brake Booster > Clear DTCs 

  Result

  Proceed to
  NEXT

Post-procedure1

• Turn the ignition switch off.

Result: 

NEXT 

See step  3

Pre-procedure1

• Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.

• Check if the same DTC is output.

  Chassis > Brake Booster > Trouble Codes 

  Result

  Result	Proceed to
  C12F8-12 and C12F8-14 are not output	A
  C12F8-12 or C12F8-14 is output	B

Post-procedure1

• None

Result: 

A 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2020 - ] 

Result: 

B 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

Pre-procedure1

• Turn the ignition switch off.

• Make sure that there is no looseness at the locking part and the connecting part of the connector.

  OK

  The connector is securely connected.

Pre-procedure2

• Disconnect the A5 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.

• Check both the connector case and the terminals for deformation and corrosion.

  OK

  No deformation or corrosion.

• Measure the voltage according to the value(s) in the table below.

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  A5-14 (+BI1) - Body ground	Always	11 to 14 V	V

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition	Result
   A5-15 (BS) - Body ground	Always	11 to 14 V	V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR