2005 SCION tC (EWD572U)
138
ABS and Tire Pressure Warning System
∗ ABS system
This system controls the respective brake fluid pressures acting on the disc brake cylinders of the right front wheel, left front
wheel and rear wheels when the brakes are applied in a panic stop so that the wheels do not lock. This results in improved
directional stability and steerability during panic braking.
1. Input Signals
(1) Speed sensor signal
The speed of the wheels is detected and input to TERMINALS 9, 11, 31 and 33 of the skid control ECU with actuator.
(2) Stop light SW signal
A signal is input to TERMINAL 10 of the skid control ECU with actuator when the brake pedal is depressed.
2. System Operation
During sudden braking the skid control ECU with actuator has signals input from each sensor, which controls the current to
the solenoid inside the actuator and lets the hydraulic pressure acting on each wheel cylinder escape to the reservoir. The
pump inside the actuator is also operating at this time and it returns the brake fluid from the reservoir to the master cylinder,
thus preventing locking of the vehicle wheels.
If the skid control ECU with actuator judges that the hydraulic pressure acting on the wheel cylinder is insufficient, the current
on the solenoid is controlled and the hydraulic pressure is increased. Holding of the hydraulic pressure is also controlled by
the skid control ECU with actuator, by the same method as above. Pressure reduction, holding and increase are repeated to
maintain vehicle stability and to improve steerability during sudden braking.
∗ Tire pressure warning system
The air pressure sensor (Speed sensor) installed in the tire wheel detects the tire air pressure. When the detected tire air
pressure is below a specified level, the warning light in the combination meter comes on to inform the driver.
S2, S3 Speed Sensor (Front LH), (Front RH)
2–1 : Approx. 1.6 kΩ (20°C, 68°F)
S18, S19 Speed Sensor (Rear LH), (Rear RH)
2–1 : Below 1.45 kΩ (25°C, 77°F)
S1 Skid Control ECU with Actuator
2, 24–Ground : Always continuity
25–Ground : Approx. 12 volts with the ignition SW at ON position
10–Ground : Approx. 12 volts with the brake pedal depressed
1, 23–Ground : Always approx. 12 volts
: Parts Location
Code See Page Code See Page Code See Page
A6 32 J5 B 35 S2 33
A7 34 J7 35 S3 33
B2 32 J9 35 S8 35
C6 34 P1 33 S18 37
D4 34 P6 35 S19 37
J4 A 35 S1 33 T6 35
:
Relay Blocks
Code See Page Relay Blocks (Relay Block Location)
2 22 Engine Room R/B (Engine Compartment Left)
:
Junction Block and Wire Harness Connector
Code See Page Junction Block and Wire Harness (Connector Location)
1B 24 Engine Room Main Wire and Instrument Panel J/B (Lower Finish Panel)
1C
1D
24
Instrument Panel Wire and Instrument Panel J/B (Lower Finish Panel)
1M
Instrument Panel Wire and Instrument Panel J/B (Lower Finish Panel)
1S
25
System Outline
Service Hints
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