Toyota Tundra Service Manual: System Description

Toyota Tundra Service Manual / Brake / Brake Control / Dynamic Control Systems / Trailer Brake Control System / System Description

SYSTEM DESCRIPTION

1. FUNCTION DESCRIPTION

*1	Trailer Brake Control Switch	*2	GAIN (+/-) Selection Button
*3	Manual Trailer Brake Output Slider	*4	Steering Pad Switch Assembly

(a) Steering Pad Switch Assembly:

(1) The trailer brake type can be set by operating the steering pad switch assembly.

(b) GAIN (+/-) Selection Button:

(1) The amount of brake force output to the trailer brake (gain value) can be set by operating the GAIN (+/-) selection button.

The gain value can be adjusted from 0 (no trailer brake) to 10 (maximum output) in 0.5 increments.

The gain value can be increased/decreased by pressing the button.

The gain value is displayed on the combination meter (multi-information display).

(1) The trailer brake can be operated by changing the position of the manual trailer brake output slider. When the manual trailer brake output slider is operated while the vehicle is braking, the larger of the 2 outputs is output to the trailer brake.

2. SETTING THE GAIN

(a) It is necessary to set the gain value according to the specific towing condition.

Adjust the gain setting every time the vehicle load, trailer load, road condition or weather changes.

When the gain value is set to 0 (no trailer brake), there is no output from the trailer brake control ECU (brake control with bracket relay).

3. TRAILER BRAKE TYPE SETTING

(a) The trailer brake type can be set by operating the steering pad switch assembly.

(1) Trailer brake type

When the steering pad switch assembly is operated, the trailer brake type is shown on the combination meter (multi-information display).

Set the trailer type according to the type of the connected trailer.

TBC Trailer Type	Multi-information Display
Electric (Light Trailer)*	Electric 0-4999lb
Electric (Heavy Trailer)	Electric 5000+lb
Electric-Over-Hydraulic (Light Trailer)	E-O-H 0-4999lb
Electric-Over-Hydraulic (Heavy Trailer)	E-O-H 5000+lb
TBC Off	TBC OFF

*: Default setting

4. FUNCTION OF COMPONENTS

Components		Functions
Trailer brake control switch	GAIN (+/-) selection button	Selects the amount of braking force for the trailer brake.
Trailer brake control switch	Manual trailer brake output slider	Operates the trailer brake only via manual operation.
Trailer brake control ECU (brake control with bracket relay)		Receives the master cylinder pressure signal from the skid control ECU (brake actuator assembly) and outputs a signal to the trailer brake. When the manual trailer brake output slider is operated, outputs a signal to the trailer brake. When the GAIN (+/-) selection button is operated, sets the amount of brake force output to the trailer brake (gain value). When the steering pad switch assembly is operated, sets the trailer brake type.
Skid control ECU (brake actuator assembly)		Outputs signals such as the vehicle speed signal and master cylinder pressure to the trailer brake control ECU (brake control with bracket relay).
ECM		Outputs the dynamic radar cruise control system brake request signal* to the trailer brake control ECU (brake control with bracket relay).
Acceleration sensor (airbag sensor assembly)		Outputs the vehicle acceleration/deceleration information signal to the trailer brake control ECU (brake control with bracket relay).
Millimeter wave radar sensor assembly*		Outputs the pre-collision system deceleration request signal to the trailer brake control ECU (brake control with bracket relay).
Steering pad switch assembly		Changes the trailer type displayed on the multi-information display.
Combination meter	Multi-information display	Displays the trailer link state. Displays the gain value. Displays output according to the manual trailer brake output slider operation. Displays the trailer brake type. Displays error notifications.

*: w/ Dynamic Radar Cruise Control System

5. COOPERATIVE CONTROL FUNCTION

(a) Trailer brake control performs cooperative control together with the following controls and systems.

Driver brake control
Anti-lock brake system
Hill-start assist control
Trailer sway control
Pre-collision system*
Dynamic radar cruise control system*

*: w/ Dynamic Radar Cruise Control System

Precaution

System Diagram

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