Input Signal; System Operation - Toyota Tundra 2003 Electrical Wiring Diagram

ABS
SYSTEM OUTLINE
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 SIGNAL

(1) Speed sensor signal
The speed of the wheels is detected and input to TERMINALS FL+, FR+, RL+ and RR+ of the ABS actuator with ECU.
(2) Stop light SW signal
A signal is input to TERMINAL STP of the ABS actuator with ECU when the brake pedal is depressed.

2. SYSTEM OPERATION

During sudden braking, the ABS actuator with ECU which has signals input from each sensor lets the hydraulic pressure
acting on each wheel cylinder escape to the reservoir.
The pump inside the ABS actuator with ECU is also operating at this time and it returns the brake fluid from the reservoir to
the master cylinder, thus preventing locking of vehicle wheels.
If the ABS actuator with ECU judges that the hydraulic pressure acting on the wheel cylinder is insufficient, the current acting
on the 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
A6, A7 ABS SPEED SENSOR FRONT LH, RH
1–2 : 0.92–1.22 kΩ (20°C, 68°F)
A19 ABS SPEED SENSOR REAR
1–2 : 0.89–1.29 kΩ (20°C, 68°F)
3–4 : 0.89–1.29 kΩ (20°C, 68°F)
A5 ABS ACTUATOR WITH ECU
6–GROUND : 10–14 volts with ignition SW at ON or ST position
24–GROUND : 10–14 volts with stop light SW on (Brake pedal depressed)
2, 18–GROUND : Always continuity
S4 STOP LIGHT SW
2–1 : Closed with brake pedal depressed
: PARTS LOCATION
Code
30 (2UZ–FE)
A5 A5
32 (5VZ–FE)
30 (2UZ–FE)
A6 A6
32 (5VZ–FE)
30 (2UZ–FE)
A7 A7
32 (5VZ–FE)
: RELAY BLOCKS
Code See Page
2 21
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
Code See Page
22 (*2)
1F 1F
26 (*1)
22 (*2)
1K 1K
26 (*1)
* 1 : w/ Daytime Running Light
158
See Page Code
A19 A19
C11
C13
D6
J5
Relay Blocks (Relay Block Location)
Engine Room R/B (Engine Compartment Left)
Junction Block and Wire Harness (Connector Location)
Cowl Wire and Driver Side J/B (Lower Finish Panel) Cowl Wire and Driver Side J/B (Lower Finish Panel)
Engine Room Main Wire and Driver Side J/B (Lower Finish Panel) Engine Room Main Wire and Driver Side J/B (Lower Finish Panel)
* 2 : w/o Daytime Running Light
2003 TOYOTA TUNDRA (EWD491U)
See Page
36 (Access Cab)
37 (Standard Cab)
A 34
C 34
34
35
* 3 : Bench Seat
Code
J8 35
J10 35
J13 35
S4 35
* 4 : Separate Seat, Captain Seat (w/o Power Seat)
See Page