Toyota 4RUNNER 2007 Electrical Wiring Diagram page 265

ABS, TRAC, VSC, Auto LSD, DAC and HAC
System Outline
1. Normal Operation
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.
The followings are two possible circumstances in which the tires exceed their lateral grip limit. The VSC system is designed
to help control the vehicle behavior by controlling the engine output and the brake at each wheel when the vehicle is under
one of the conditions indicated below.
∗ When the front wheels lose grip in relation to the rear wheels (Strong front wheel skid tendency).
∗ When the rear wheels lose grip in relation to the front wheels (Strong rear wheel skid tendency).
2. Electronic Brake–Force Distribution
Skid control ECU with actuator distributes appropriate brake–force to front and rear wheels (Control of brake–force
distribution to front and rear wheels) corresponding to the vehicle driving conditions. It also makes effective use of rear wheel
brake–force to match the loading condition and decelerating of the vehicle, resulting in reducing brake pedal depression and
ensuring effective braking. In braking during making a turn, the ECU controls appropriate brake–force distribution to right and
left wheels (Control of brake–force distribution to right and left wheels) to ensure stability and braking of the vehicle.
3. Downhill Assist Control Operation
The downhill assist control operation controls braking action of each wheel to help prevent an out–of–balance posture of the
vehicle when descending a steep hill or traveling at a speed exceeding the threshold of wheel gripping capability. When the
downhill assist control is in operation, the brake system controls vehicle speed within the range of 5 to 7 km/h.
For the downhill assist control to be operative, all of the following conditions have to be met:
∗ Downhill assist control switch = ON
∗ Transfer L4 selected
∗ Vehicle speed is 5 km/h or more, but less than 25 km/h.
∗ Accelerator pedal OFF
∗ Brake pedal OFF
4. Hill–Start Assist Control Operation
When starting on a steep hill for ascending, the hill–start assist control automatically puts the brake on momentarily when the
driver switches from the brake pedal to the accelerator pedal, to help the driver start the vehicle safely and smoothly.
Please bear in mind, however, that it activates the brake system only for 3 seconds.
For the hill–start assist control to be operative all of the following conditions have to be met:
∗ Shift position = D, 2, or L
∗ No vehicle move due to wheel slip
∗ Vehicle speed > 0 km/h
5. Active TRAC (4WD)
During rugged off–road driving, this function controls the engine output and the brake fluid pressure that is applied to the
slipping wheel, and distributes the drive force that would have been lost through the slippage to the remaining wheels in
order to achieve a LSD effect.
6. Auto LSD (2WD)
Auto LSD fulfills the function of LSD by using the system of TRAC. It helps ensures to recover from run–off condition and to
take off on roads with much travel resistance such as sand.
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4RUNNER (EM03M0U)