BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C120B; IG Supply Voltage Low; 2018 - 2020 MY Sienna [11/2017

Last Modified: 04-05-2023	6.11:8.1.0	Doc ID: RM1000000018KE8
Model Year Start: 2018	Model: Sienna	Prod Date Range: [11/2017 - ]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C120B; IG Supply Voltage Low; 2018 - 2020 MY Sienna [11/2017 - ]

DTC

C120B

IG Supply Voltage Low

DESCRIPTION

DTC No.	DTC Detection Condition	Trouble Area
C120B	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)

Refer to DTC C1417 (See page ).

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 inspection 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 connectors.

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

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A75-38 (+BS) - Body ground	Ignition switch ON	11 to 14 V
A75-38 (+BS) - A75-25 (GND1)	Ignition switch ON	11 to 14 V

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

2.	RECONFIRM DTC

(a) Reconnect the A75 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs (See page ).

(d) Turn the ignition switch to ON.

(e) Check if the same DTC is output (See page ).

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