Ford Falcon. Manual — part 79

206-09-5

Anti Lock Control

206-09-5

DESCRIPTION AND OPERATION (Continued)

NOTE: LPG (Liquefied Petroleum Gas) conversions

ABS

are not compatible with traction control. If an LPG

If a system defect is detected, the ABS will switch

conversion is performed it must conform with Ford

itself OFF. The driver can still use the base brake

recommendations and must be performed by an

system without the anti-lock feature. This change over

approved LPG installer. The traction control will not

is indicated by means of illuminating the ABS warning

operate whilst LPG is the selected fuel. If the

light on the instrument panel.

conversion does not meet Ford recommendations the

rear brakes may overheat.

TCS

If a system defect is detected in the traction control

Electronic Brake-Force Distribution (EBD)

only, the traction control part of the TCS will switch

The Brake-Force Distribution is controlled by omitting

itself OFF. The ABS will remain functional. If some

the currently used mechanical proportional valve(s)

other fault occurs in the TCS the complete system

and controlling the pressure to the rear wheels via the (ABS and traction control) will switch itself OFF. The

current Anti-Lock Brake System (ABS).

driver can still use the base brake system without the

The information as to when and how much the master anti-lock feature, and can still accelerate and drive

cylinder pressure is to be proportioned, is received

normally without the traction control feature. This

from the rear and front Wheel Speed Sensors (WSS). change over is indicated by means of illuminating both

This difference in slip between the front and rear

the ABS and the traction control warning lights on the

wheel speeds, is calculated and then reacted upon by instrument panel.

the ABS assembly.

Modulator and ECU

The EBD operation takes effect prior to the increased

slip rate required for ABS intervention.

The ECU uses the inputs from the wheel speed

sensors to determine if ABS [or traction control]

The ABS unit has additional software that will, in the

operation is necessary, and if so, energises the

case of an EBD operation, operate the rear inlet

solenoids to control hydraulic brake pressure [and

valves of the ABS Hydraulic Modulator Assembly.

communicates the desired wheel torque to the EEC].

These inlet valves will open and close as required, to

The ECU controls all diagnostic functions and

control the amount of pressure that can be applied to

monitors all external inputs and outputs.

the rear wheels before ABS is required.

NOTE: The ABS modulator and ECU is serviced only

If the restriction of the pressure, by closing the rear

as a complete assembly. The ECU should not be

inlet valves, does not prevent the slip from continuing

removed from the modulator body.

to increase at the rear axle, the outlet valve will open

and allow a reduction of the pressure to be transferred

to the accumulator of the ABS unit. The pump motor

does not operate at this stage and is therefore not in

ABS mode.
If then the pressure reduction is not sufficient to

reduce the rear wheel slip, a normal ABS operation

will take place.
The EBD uses a select low logic on the rear wheels,

that is, the condition of the rear wheel with the least

amount of traction is duplicated on the opposing

wheel.

Self-Monitoring

When the vehicle is started, the system automatically

carries out a static system analysis. Wheel speed

sensors are checked for continuity, solenoid valves

Sensors and Tone Wheels

and the pump motor are operated, feedback signals

Each wheel is fitted with a sensor and tone wheel.

from the valves and motor are monitored [and

The front sensors are attached to the steering spindle

communication with the EEC is acknowledged].

and the tone wheels are pressed onto the hub

As the vehicle is driven the system monitors itself by

assembly. At the rear, sensors are attached to the

comparing the input and output signals of the valves

differential housing for (IRS) or the parkbrake back

with memorised limit values, in addition to monitoring

plate (for beam axle), whilst the tone wheels are

the voltage supply. It also continuously compares the

attached to the drive shafts. Each tone wheel

wheel speed signals with each other [and

incorporates teeth which generate pulses in the wheel

continuously exchanges information with the EEC].

sensor. These pulses are used by the ECU to

calculate wheel speeds and acceleration rates.

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Anti Lock Control

206-09-6

DESCRIPTION AND OPERATION (Continued)

ABS Indicator Light

Sensor and Tone Wheel — Front

This light will illuminate each time the ignition is turned

to the ON position and will go out after approximately

2 seconds. In the event that the ABS light remains on,

or illuminates constantly while driving, this indicates

that the ABS function is disabled. and should receive

immediate attention to restore the benefits of the ABS

features. If the fault is of a temporary nature, the ABS

will reset on the next ignition cycle and the light will

then return to normal operation. However, a fault code

will be stored in the ECU - see Diagnosis and Testing

later in this section.
NOTE: Most malfunctions in the ABS system will

cause the indicator light to illuminate indicating the

system has been disabled. Normal braking is not

affected unless the brake warning light is also

Sensor and Tone Wheel — Rear (IRS)

illuminated.

Traction Control (TCS) Indicator Light

This light will illuminate, along with the ABS light, each

time the ignition is turned to the ON position and will

go out after approximately 3 seconds. If the traction

control light flashes while driving this indicates that

one or both of the drive wheels are spinning and that

the TCS is applying brakes and/or reducing engine

power. In the event that the traction control light

remains on, or illuminates constantly while driving,

this indicates that the function is disabled. If it cannot

be enabled by pressing the traction control on/off

switch it should receive immediate attention to restore

the benefits of the traction control features.
If the fault is of a temporary nature, the traction

Sensor and Tone Wheel — Rear (Live Axle)

control will reset on the next ignition cycle and the

Wagon and Ute

light will then return to normal operation. However, a

fault code will be stored in the ECU - see Diagnosis

and Testing later in this section.
NOTE: The traction control light can be illuminated by

turning the traction control off with the switch on the

dash. If only the traction control light is on, the ABS

function is not affected.

Traction Control Switch (TCS)

The TCS is used to toggle the traction control feature

on/off depending on the driver’s preference at the

time. When the traction control is turned off, the

indicator light will illuminate and stay on until the

system is again reactivated. The system may be

reactivated by pressing the switch again.

Brake Pipes

Traction control is turned on each time the ignition is

cycled regardless of whether the system was on or off

The hydraulic connections are by conventional steel

previously.

brake tubing. Two master cylinder pipes are

connected to the inlets of the hydraulic modulator.

Operating Modes

The three [four] outlets of the hydraulic modulator are

connected individually to the front brake calipers and

The hydraulic modulator executes ABS/TCS ECU

as a pair [TCS-individually] to the rear brake calipers.

commands using six [ten], two-position solenoid

valves, [including a priming valve, and a switching

valve]. The hydraulic modulator valve positions

correspond to various ABS/TCS ECU control phases:

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206-09-7

Anti Lock Control

206-09-7

DESCRIPTION AND OPERATION (Continued)

1. Non

ABS/TCS

condition

ABS Braking - Standard braking no ABS

assistance

2. Maintaining pressure (ABS)
3. Reducing pressure (ABS)

During this condition, both build and decay valves are

not energised; that is the ABS ECU does not supply

4. Increasing pressure (ABS)

any current to the solenoid coils, and this provides for

5. Traction control in operation (brake intervention)

conventional non ABS braking.

For explanation of ABS operation, only one segment

From the brake master cylinder, hydraulic pressure is

of the system will be described. For explanation of

applied to brake circuit. If the ABS ECU does not

traction control operation, only the part of the system

detect any rapid wheel deceleration, the ABS will

related to the rear wheels will be described.

remain passive at this time.

ABS Braking - Standard braking no ABS assistance

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206-09-8

Anti Lock Control

206-09-8

DESCRIPTION AND OPERATION (Continued)

TCS operation - No ABS or Trac control

assistance

This is a schematic of the Hydraulic Modulator under

normal driving conditions. All the valves are in their

normal rest position allowing uninterrupted flow for

normal braking conditions. This is depicting no

pressure within the system, therefore, no application

of brakes.
Status

Inlet Valve

Outlet Valve

Prim-

Swit- Motor

ing

ching

Valve Valve

Left Right

Left

Right Closed Open

Off

Open Open Closed Closed

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