Toyota Supra 2015 Wiring Diagram Manual page 155

ABS (W/ TRACTION CONTROL)
SYSTEM OUTLINE
THIS SYSTEM CONTROLS THE RESPECTIVE BRAKE FLUID PRESSURES ACTING ON THE DISC BRAKE CYLINDERS
OF THE RIGHT FRONT WHEEL, LEFT FRONT WHEEL, RIGHT REAR WHEEL AND LEFT REAR WHEEL WHEN THE
BRAKES ARE APPLIED IN A PANIC STOP SO THAT THE WHEELS DO NOT LOCK.
THIS RESULTS IN IMPROVED DIRECTIONALLY STABILITY AND STEERABILITY DURING PANIC BRAKING.
1. INPUT SIGNALS
(3) SPEED SENSOR SIGNAL
THE SPEED OF THE WHEELS IS DETECTED AND INPUT TO TERMINALS FL+, FR+, RL+ AND RR+ OF THE ABS
ECU.
(4) STOP LIGHT SW SIGNAL
A SIGNAL IS INPUT TO TERMINAL STP OF THE ABS ECU WHEN THE BRAKE PEDAL IS DEPRESSED.
(5) DECELERATION SENSOR SIGNAL
LONGITUDINAL AND LATERAL ACCELERATION IS DETECTED AND INPUT TO THE ABS ECU.
2. SYSTEM OPERATION
DURING SUDDEN BRAKING, THE ABS ECU WHICH HAS SIGNALS INPUT FROM EACH SENSOR CONTROLS THE
CURRENT FLOWING 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 ECU JUDGES THAT THE HYDRAULIC PRESSURE ACTING ON THE WHEEL CYLINDER IS INSUFFICIENT, THE
CURRENT ACTING ON SOLENOID IS CONTROLLED AND THE HYDRAULIC PRESSURE IS INCREASED.
HOLDING OF THE HYDRAULIC PRESSURE IS ALSO CONTROLLED BY THE ECU, BY THE SAME METHOD AS ABOVE,
BY REPEATED PRESSURE REDUCTION, HOLDING AND INCREASE ARE REPEATED TO MAINTAIN VEHICLE
STABILITY AND TO IMPROVE STEERABILITY DURING SUDDEN BRAKING.
SERVICE HINTS
A20 (A), A21 (B) ABS ECU
(A) 13-GROUND::10-14 VOLTS WITH THE IGNITION SW AT ON POSITION
(A) 5-GROUND:10-14 VOLTS WITH THE STOP LIGHT SW ON
(A) 12,(A) 25-GROUND:ALWAYS CONTINUITY
A 6 (A), A 7 (B) ABS ACTUATOR
(A) 1-GROUND:ALWAYS CONTINUITY
(A) 5-(A) 4.33
(B) 1, (B) 2, (B) 3, (B) 4- (A) 4,:APPROX. 8 8
(B) 5, (B) 6, (B) 7, (B) 8- (A) 4,:APPROX. 4.3
S11 STOP LIGHT SW
2-1:CLOSED WITH THE BRAKE PEDAL DEPRESSED
A10, A11 ABS SPEED SENSOR FRONT LH, RH
1-2:0.4-1.8 K (20 C, 68 F)
A31, A32 ABS SPEED SENSOR REAR LH, RH
1-2:0.9-1.3 K (20 C, 68 F)
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