TOYOTA CAMRY 2000 Service Repair Manual

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 MASTER CYLINDER
As in the previous model, the lockheed and
lockheed type master cylinder is used on the models
without ABS, and the portless and lockheed type
master cylinder is used on the models with ABS.
The portless and portless type master cylinder is
used on the models with ABS & TRAC system.
 ABS
1. General
As in the previous model, the braking of each wheel is controlled by the following 3 modes: pressure reduction,
pressure holding, and pressure holding mode.
During ABS activation, the ECU controls the fluid pressure of each front left and right wheels independently while
the fluid pressure of rear left and right wheels is controlled simultaneously.
However, the ABS actuator has been changed as shown in the table below. In addition, the diagnostic codes have
alsom been changed.
For diagnostic code check method, diagnostic code and diagnostic code clearance, see the 1997 Camry Repair
Manual (Pub. No. RM503U).
The operation of the ABS is the same as that of the '96 Corolla.

Type of ABS Actuator
Model
NewPreviousTypeNewPrevious
NIPPONDENSO ABS
(TMC Produced Model) 2±Position Solenoid Valve Type
Actuator
The ECU and realy are separate.3±Position Solenoid Valve Type
Actuato
The ECU and relay are separate.
BOSCH ABS
(TMM Produced Model)2±Position Solenoid Valve Type
Actuator with ECU and Relay3±Position Solenoid Valve and
Mechanical Valve Type Actuator
with ECU and Relay

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2. System Diagram

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3. Wiring Diagram
TMC Produced Model

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TMM Produced Model

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4. Hydraulic Circuit
The hydraulic circuit of the Nippondenso and Bosch systems are the same.
5. Operation
The hydraulic system of the ABS has 4 circuits. Although the hydraulic circuit described below is 1 circuit, it is
applicable to other circuits as well.
During Normal Braking (ABS not activated)
During normal braking, the ABS is not activated
and the ECU does not send control signal. When the
brake pedal is depressed, the fluid pressure in the
master cylinder rises, brake fluid passes from port
A to port B, and then flows to the brake wheel
cylinder. When the brake pedal is released, brake
fluid returns from the brake wheel cylinder to the
master cylinder through port B to port A and the No.
1 Check Valve.

Condition of Each Valve and Pump Motor
Part Name
Signal from
ABS ECUOperation
Pressure
Holding ValveOFFPort AOpen
Pressure
Reduction
Valve
OFFPort DClosed
Pump MotorOFFRotating

Hydraulic Circuit

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During Normal Braking (ABS not activated)
1) Pressure Reduction Mode
When the wheel is about to lock, the control signal
from the ECU causes port A to close, port D to open,
thus engaging the pressure reduction mode.
At this time, the brake fluid flows from the wheel
cylinder, through ports C and D, to the reservoir,
reducing the wheel cylinder pressure. At the same
time, the brake fluid is pumped and returned to the
master cylinder.

Condition of Each Valve and Pump Motor
Part Name
Signal from
ABS ECUOperation
Pressure
Holding ValveONPort AClosed
Pressure
Reduction
Valve
ONPort DOpen
Pump MotorONRotating
2) Pressure Holding Mode
After the fluid pressure in the wheel cylinder is
reduced or increased to the required pressure, a
control signal fromt he ECU causes ports A and D
to close. As a result, the system engages in the
pressure holding mode to maintain the fluid
pressure in the wheel cylinder.

Condition of Each Valve and Pump Motor
Part Name
Signal from
ABS ECUOperation
Pressure
Holding ValveONPort AClosed
Pressure
Reduction
Valve
OFFPort DClosed
Pump MotorONRotating

Hydraulic Circuit

Hydraulic Circuit

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3) Pressure Increase Mode
When the fluid pressure in the wheel cylinder needs
to be increased in order to apply more braking force,
a control signal from the ECU causes port A to open,
port D to close, thus engaging in the pressure
increase mode.
Accordingly, the circuit will be in the same state as
in normal braking, in chich the brake fluid is sent
from the master cylinder to the wheel cylinder to
increase the fluid pressure in the wheel cylinder.
The fluid pressure increase rate is controlled by
repetition of the pressure increase and pressure
holding mode.

Condition of Each Valve and Pump Motor
Part Name
Signal from
ABS ECUOperation
Pressure
Holding ValveOFFPort AOpen
Pressure
Reduction
Valve
OFFPort DClosed
Pump MotorONRotating

Hydraulic Circuit

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 ABS & TRAC SYSTEM
1. General
The ABS & TRAC system totally controls the engine torque control through the fuel cutoff and the braking of the
driving wheels (front wheels). If helps to avoid slippage of the driving wheels that tends to happen during starting
and acceleration and to maintain an optimal driving force according to the road surface conditions. The system
eliminates the need for a subtle accelerator pedal opeation and ensures vehicle stability when starting, accelerating
or turning on slippery roads.
2. System Diagram

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3. Wiring Diagram

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4. Layout of Components