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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 37 (Electronically Controlled Brake System (HV) - Diagnostic Codes (08 Of 11)) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model) >> DTC C12F8-12: ECB Solenoid Control "A" Circuit Short to Battery; DTC C12F8-14: ECB Solenoid Control "A" Circuit Short to Ground or Open [11/2023 - ] >> Description

DTC C12F8-12: ECB Solenoid Control "A" Circuit Short to Battery; DTC C12F8-14: ECB Solenoid Control "A" Circuit Short to Ground or Open [11/2023 - ]: Description

WARNING: This page is about a different variant/trim than selected.

The main relay is built into the No. 1 skid control ECU (brake booster with master cylinder assembly).

The main relay supplies power to the switching solenoid and the linear solenoid.

The main relay remains on for approximately 4 minutes after the ignition switch is turned off and the input of brake pedal operation signals stops, and supplies power to the system to keep it ready to operate.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Note
C12F8-12 ECB Solenoid Control "A" Circuit Short to Battery When there is a main relay off command from the ECU, 3.5 V or more is detected at terminal BS for 4.5 seconds or more.
  • Short in main relay circuit
  • Main relay internal stuck
  • Wire harness and connector
  • No. 1 skid control ECU (brake booster with master cylinder assembly)
Comes on
  • SAE Code: C12FB
  • Output ECU: Both skid control ECUs
  • ECB: Electronically Controlled Brake System
C12F8-14 ECB Solenoid Control "A" Circuit Short to Ground or Open Either of the following is detected:
  • When the ignition switch is turned to ON (READY):

    The BS terminal voltage is less than 3.8 V for 0.05 seconds or more, when the IG1 terminal voltage is 9.5 V or more and operation of the main relay is requested.

  • When the ignition switch is off:

    The BS terminal voltage is less than 3.8 V for 0.05 seconds or more, when operation of the main relay is requested.

  • Open or short in main relay circuit
  • Wire harness and connector
  • No. 1 skid control ECU (brake booster with master cylinder assembly)
Comes on
  • SAE Code: C12FA
  • Output ECU: Both skid control ECUs
  • ECB: Electronically Controlled Brake System