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:

Inspection
INSPECTION PROCEDURE 1. INSPECT FRONT NO. 1 SPEAKER ASSEMBLY (w/o Amplifier Box Speaker Assembly) (a) Measure the resistance according to the value(s) in the table below. Standard resistance: Tester Connection Condition Specified Condition 1 ...

Lost Communication with ECM / PCM "A" (U0100,U0125,U0126,U0129)
DESCRIPTION These DTCs are stored when a communication malfunction occurs between ECUs that perform pre-collision system control. DTC No. Detection Item DTC Detection Condition Trouble Area U0100 Lost Communication with ECM ...

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 assembly has a built-in yaw rate and acceleration sensor and detects the vehicle condition. If th ...