Toyota Tacoma (2015-2018) Service Manual: System Description

SYSTEM DESCRIPTION

1. SYSTEM DESCRIPTION

HINT:

The skid control ECU is built into the hydraulic brake booster.

(a) ABS (Anti-lock Brake System)

The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.

(b) Multi-terrain Anti-lock Brake System (Multi-terrain ABS)

This function detects off-road driving in sand, mud, gravel, dirt and so on based on signals from the yaw rate and acceleration sensor, the speed sensor and the ECM, and then automatically switches to the ABS control most appropriate for the current road conditions.

(c) EBD (Electronic Brake force Distribution)

The EBD control utilizes ABS, realizing proper brake force distribution between the front and rear wheels in accordance with the driving conditions.

In addition, when braking while cornering, it also controls the brake forces of the right and left wheels, helping to maintain the vehicle stability.

(d) VSC (Vehicle Stability Control)

The VSC system helps prevent the vehicle from slipping sideways as a result of strong front wheel skid or strong rear wheel skid during cornering.

(e) TRAC (Traction Control)

The TRAC system helps prevent the drive wheels from slipping if the driver presses down on the accelerator pedal excessively when starting off or accelerating on a slippery surface.

HINT:

The TRAC system operates when H2 (2WD) mode is selected.

(f) A-TRAC (Active Traction Control)

During rugged off-road driving, this function controls the brake fluid pressure that is applied to slipping wheels, and distributes the drive force that would have been lost through the slippage to the remaining wheels in order to achieve an LSD (Limited Slip Differential) effect. As a result, the vehicle's off-road drivability and ability to free itself from ruts have been increased.

HINT:

The A-TRAC system operates when L4 (Low speed 4WD) mode is selected.

(g) AUTO-LSD (Auto Limited Slip Differential)

When the vehicle is in H2 (2WD) mode, the AUTO LSD will operate with the VSC OFF switch on (TRAC OFF mode (AUTO LSD control)) and the accelerator pedal depressed.

The AUTO LSD system is used to apply brake pressure and limit differential slippage, thus transmitting drive torque to the other drive wheel to ensure traction when starting under the following conditions:

HINT:

The AUTO LSD system operates when H2 (2WD) mode is selected.

(h) Hill-start Assist Control

When the vehicle starts off on a steep hill, hill-start assist control detects the backward descent of the vehicle and effects 4-wheel hydraulic pressure control to reduce the speed of the vehicle.

For a Maximum of 5 seconds after the control starts, fluid pressure is gradually released and the control is complete.

HINT:

Depressing the brake pedal cancels control of the hill-start assist control system.

Does not operate when the shift lever in P or N, or when the vehicle is running/rolling back up a slope with the shift lever in R.

(i) Crawl (Crawl Control)

Crawl control is a system that provides assistance when driving on bumpy off-road surfaces, slippery road surfaces, etc. When crawl control is operating, the engine output and braking force are controlled automatically to enable driving while maintaining a constant speed. As a result, the driver can concentrate on steering the vehicle without having to operate the accelerator and brake pedals very much.

(j) Multi-terrain Select Control

When multi-terrain select control is active, A-TRAC brake control and engine output control most appropriate for the selected road mode are performed automatically. In this way, superior off-road driveability is achieved.

(k) Trailer Sway Control

If the vehicle is towing a trailer with an inappropriate hitch load, trailer sway could be caused by crosswinds, imbalance caused by the load, or the driver's steering. Trailer sway control reduces trailer sway by controlling the engine output and the braking of each wheel.

2. FUNCTION OF COMPONENTS