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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 C137B-A2: Brake System Control Module "A" System Voltage System Voltage Low [12/2019 - 10/2021] >> Monitor Description

Monitor Description

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

C137C (Case 1): 

  1. When the voltage of IG1 or IG2 is excessively low, the No. 2 skid control ECU (brake actuator assembly) detects that the power supply voltage is excessively low, the MIL is illuminated and a DTC is stored.

C137C (Case 2): 

  1. When the power supply voltage to all speed sensors is excessively low, the No. 2 skid control ECU (brake actuator assembly) judges that the power supply voltage is excessively low, the MIL is illuminated and a DTC is stored.

C137C (Case 3, 4 and 5): 

  1. When the voltage at terminal +BS is less than 8.5 V and the data of the master cylinder pressure sensor, brake pedal stroke sensor assembly or wheel cylinder pressure sensor is invalid for a certain amount of time, the No. 2 skid control ECU (brake actuator assembly) judges that the power supply voltage is excessively low, the MIL is illuminated and a DTC is stored.

C137C (Case 6): 

  1. When the power supply voltage of the solenoid is excessively low for a certain amount of time, the No. 2 skid control ECU (brake actuator assembly) judges that the output of the solenoid relay is abnormal due to excessively low voltage, the MIL is illuminated and a DTC is stored.

C137C (Case 7): 

  1. The No. 2 skid control ECU (brake actuator assembly) monitors the current of the motor fail-safe relay. When overcurrent is detected in the motor circuit, the No. 2 skid control ECU (brake actuator assembly) judges that the motor output is abnormal due to excessively low voltage, the MIL is illuminated and a DTC is stored.
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