Toyota Tacoma (2015-2018) Service Manual: IG Supply Voltage Low (C120B)

Toyota Tacoma (2015-2018) Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / IG Supply Voltage Low (C120B)

DESCRIPTION

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C120B	IG Supply Voltage Low	Master cylinder pressure sensor power supply voltage decrease occurs or history of voltage decrease exists, and defective master cylinder pressure sensor output continues for 1 second or more.	Master cylinder pressure sensor output defective Skid control ECU (Brake actuator assembly) ABS NO. 2 fuse

WIRING DIAGRAM

Refer to DTC C1417 (See page CAUTION / NOTICE / HINT ).

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information (See page ).
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (+BS TERMINAL)

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

(b) Disconnect the skid control ECU (brake actuator assembly) connector.

Standard Voltage:

Tester Connection	Condition	Specified Condition
S1-38 (+BS) - Body ground	Always	11 to 14 V
S1-38 (+BS) - S1-25 (GND1)	Always	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU [Brake Actuator Assembly])

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BS CIRCUIT)

2.	RECONFIRM DTC

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs (See page (c) Check if the same DTC is recorded (See page ).

Result

Result	Proceed to
DTC C120B is not output.	A
DTC C120B is output.	B

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE ACTUATOR ASSEMBLY

Control Module Communication Bus OFF (U0073,U0100,U0124,U0126)

DESCRIPTION The skid control ECU (brake actuator assembly) receives the signals from the ECM, steering angle sensor (spiral cable with sensor sub-assembly), 4 wheel drive control ECU*, and yaw ra ...

Zero Point Calibration of Yaw Rate Sensor Undone (C1210,C1336)

DESCRIPTION The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor (airbag sensor assembly) via the CAN communication system. The airbag sensor ...

Other materials:

System Description
SYSTEM DESCRIPTION 1. GENERAL (a) This system uses ultrasonic sensors to detect any obstacles at the corners and the rear of the vehicle. The system then informs the driver of the distance between the sensors and an obstacle as well as their positions by indicating them on the multi-informat ...

Front Occupant Classification Sensor LH Collision Detection (B1785)
DESCRIPTION DTC B1785 is set when the occupant detection ECU receives a collision detection signal, which is sent by the occupant classification sensor front LH when an accident occurs. DTC B1785 is also set when the front seat with adjuster frame assembly RH is subjected to a strong impact, ...

Reservoir Level Switch Disconnected (C1453,C1454)
DESCRIPTION The brake fluid level warning switch sends the appropriate signal to the skid control ECU (master cylinder solenoid) when the brake fluid level drops. DTC Code DTC Detection Condition Trouble Area C1453 With the ECU termina ...