1994 JAGUAR XJ6 ECU

Brakes (a)
12.1.2. Anti-lock Braking / Traction Control Operation
The rear wheels are controlled collectively on a 'select-low' principle during ABS operation. During traction control,
separate circuits allow individual control of the rear wheels. To facilitate this the valve block has four outlet ports.
The
ABS/TC CM is integrated with the valve block. The pump, motor, valve block and control module are supplied as
a unit and are non-sewiceable. Faulty units must be renewed as a whole.
Both front and rear brakes on
all vehicles are fitted with single piston caliper assemblies. Ventilated brake rotors, with
provision for parking brake shoes at the rear, are fitted all round.
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Issue 1 August 1994 X300 VSM 3
1. Vacuum booster 9. Pressure conscious reduction valve 2. Vacuum hose 10. Ventilated brake rotor 3. Tandem master cylinder 11. Single piston caliper 4. Primary brake circuit 12. %way brake pipe connector
5. Secondary brake circuit 13. Wheel speed sensor
6. Hydraulic pump / motor unit 14. ABS warning lamp 7. Valve block 15. Brake fluid level warning lamp
8. ABS/TCCM
Fig. 1 ABS / Traction Control System
The vacuum booster (see Fig.
1) is mounted on the brake pedal box and secured by three bolts. Brake pedal force is
increased by the vacuum booster which activates the Tandem Master Cylinder (TMC) intermediate piston. Brake fluid
is supplied to the pump inlet ports on two separate circuits. The primary circuit supplies the front brakes whilst the
secondary circuit supplies the rear brakes.

12.1.5. ABS Components
Hydraulic Module
The hydraulic module is located under the bonnet adjacent
to the engine compartment firewall. It is secured within a steel mounting bracket at three securing points. All elec- tronic and power connections are made through one cable
loom connect ion.
The hydraulic pump
(1 Fig. 1) is a reciprocating two-circuit pump in which one brake circuit is assigned to each pump
circuit. The pump supplies adequate pressure and volume
supply to the brake circuits under anti
-lock braking condi- tions. The pump is driven by and electric motor (2 Fig. 1). The
pump housing incorporates two low pressure accumulators
and damping chambers for each brake circuit.
A modulator valve block
(3 Fig. 1) incorporates the ABS CM or ABS / TC CM (4 Fig. 1). Vehicles with traction control are
fitted with a throttle position actuator (5 Fig. I), which is an
electrical device controlled by the ABS 1 TC CM.
Valve blocks on vehicles without traction control comprise
six solenoid valves, three normally open (NO) inlet valves
and three normally closed
(NC) outlet valves. These valve
blocks have three outlet ports. Valve blocks on vehicles with
traction control comprise nine solenoid valves, four
NO inlet valves,four NC outlet valves and one special isolating valve.
Fig. 2 shows a hydraulic module for vehicles with traction
control. The valve block (2 Fig. 2) has four outlet ports (Indi- vidual control of the driven wheels).
A BS CM, A BS / TC CM
The ABS CM or ABS TCI CM locates beneath the modulator
valve block and is secured by
two screws. The CM houses
the solenoids which operate the inlet and outletvalves of the
modulator valve block. When fitted, the valve stems locate
in the
CM mounted solenoids. There is no electrical connec- tion between the CM and the modulator valve block. Fig. 3 shows an ABS TC 1 CM having nine solenoids.
The
CM functions include the following:
0 Providing control signals for the operation of ABS
and traction control solenoid valves
0 Calculating wheel speed from voltage signals trans- mitted by the wheel speed sensors
0 Monitoring of all electrical components
0 On Board Diagnostics (OBD): storage of possible fail- ures in a non-volatile memory.
The signals from the four wheel speed sensors are indepen
- dently processed by the ABS CM or ABSITC CM, calculating
numerical values which correspond directly to the wheel
speed. These values are converted into control signals for
pressure modulation during ABS control.
The ABS and traction control
are continuously monitored,
whilst the ignition is on,for possiblefaults and interruptions.
If a fault is detected, the module deactivates the ABS and
indicates this by lighting the ABS warning lamp. In a fault
condition, conventional braking is unaffected. The module
stores fault codes in a non
-volatile memory which can be
read via the OBD link.
U: For electrical diagnostic information on the ABS I traction control systems, refer to EDM, Section 12. Fia.
1
Fia. 2
Fin. 3 I
J70286
Issue 1 August 1994 X300 VSM

0 12.1.6 Calipers
Both front and rear brakes on all vehicles are fitted with
single piston caliper assemblies that act upon 28mm thick
ventilated brake rotors (front brakes) and 20mm thickventi- lated brake rotors/hubs (rear brakes). Rear ventilated brake rotordhubs are fitted to cope with the increased demands- brought about by traction control.
The brake rotors must be renewed
whenthe minimumthick- ness specified below is reached:
0 Front brake rotor - 27mm
0 Rear brake rotor - 18.5mm.
On the front brakes (Fig. 1) two bolts secure the caliper
carrier to the suspension vertical link.
On the rear brakes (Fig. 2) two bolts (wire locked) secure the
caliper carrier to the hub carrier.
Fig. 1
\
Fig. 2
J70-278
X300 VSM 7 Issue 1 August 1994

Brakes (e#
12.1.7. Parking Brake
J70 293
W
1. Parking brake lever 2. Front cable 3. Relay lever 4. Driveshaft securing bracket 5. Intermediate cable 6. Cable equalizer
7. In-line cable connector 8. Rear cable RH 9. Rear cable LH
10. Parking brake switch and harness 11. Parking brake warning lamp
Fig.
1 Parking Brake Layout
All vehicles are fitted with identical parking brake systems.
When the parking brake lever
is operated, the cable system applies equal force to both RH and LH brakeshoe expander
assemblies. The brake shoes expand and press against the hub assembly, locking the rear wheels.
The handbrake lever, ratchet assembly and warning
light switch (item 1) are mounted on the transmission tunnel by means of threeflanged screws a blanking plate and gasket. The front cable (item 2) is connected to the relay lever (item 3) which is mounted on the driveshaft securing bracket (item 4). The relay lever operates the intermediate cable (item 5) which incorporates an adjusting screw to allow cable tension to be adjusted. The intermediate cable operates the
equalizer which ensures that equal force is applied to RH and LH parking brakesvia rearcable RH (item 8) and rear cable
LH (item 9). The rear cables are adjustable to allow cable tension to be adjusted.
The park brake switch (item 10) latches when the lever
is operated and lights the parking brake warning light (item 11 mounted in the instrument panel.
X300 VSM Issue 1 August 1994

Brakes
a 12.5 GENERAL FI77lNG lNSTRUCTlONS
12.5.1 Brake Fluid
WARNING: BRAKE FLUID IS CORROSIVE. EXTREME CARE MUST BE TAKEN WHEN HANDLING. AVOID SKIN OR EYE
CONTACT. AVOID INGESTION. IF SKIN OR EYES ARE ACCIDENTALLY SPLASHED WITH BRAKE FLUID,
RINSE THE AFFECTED AREA IMMEDIATELY WITH PLENTY OF WATER AND SEEK MEDICAL ATTENTION.
IF BRAKE FLUID
IS INGESTED, SEEK MEDICAL ATTENTION IMMEDIATELY.
CAUTION:
Fluid must not be allowed to contact the vehicle paintwork. Remove any spilt fluid from the paintwork
by rinsing away with running water. Methylated spirit (denatured alcohol) must not be used to clean the
contaminated area.
Cleaning Solvents
CAUTION: Never use methylated spirit (denatured alcohol) for cleaning purposes. Use only a proprietary brake
cleaning fluid.
m: THROUGHOUT THE FOLLOWING MAINTENANCE / SERVICE OPERATIONS, ABSOLUTE CLEANLINESS
MUST BE OBSERVED TO PREVENT GRIT OR OTHER FOREIGN MATTER CONTAMINATING THE BRAKE
TION. TO CLEAN BRAKE SYSTEM COMPONENTS, WASH
IN A PROPRIETARY BRAKE CLEANING FLUID.
REMOVE ALL TRACES OF CLEANING FLUID BEFORE REASSEMBLY. ALL BRAKE SYSTEM RUBBER COh PONENTS MUST BE DIPPED IN CLEAN BRAKE FLUID AND ASSEMBLED USING THE FINGERS ONLY.
SYSTEM.
IFTHE SYSTEM IS TO
BE FLUSHED, USE CLEAN BRAKE FLUID TO MINIMUM DOT 4 SPECIFICA-
12.5.2 Hoses
Fully release the unions (1 Fig. 1) securing each end of the
hose to the fluid pipes. Withdraw the pipe unions (1 Fig. 1) from the hose ends.
Plug the ends of the pipes (2 Fig. 1) to prevent the loss of
fluid and the ingress of dirt.
Remove the mounting bracket locknut (3 Fig. 1) and re- move the hose (4 Fig. 1).
Thoroughly clean the hose and examine for any signs of
wear or damage. Renew the hose if there is any doubt
about its condition. Thoroughly clean the bore of the hose
using compressed air.
. Remove all blanking plugs and fit the new hose to the cali- per / connector. Secure the hose to the mounting bracket.
. Before fully tightening the locknut, ensure that the hose is
neither kinked nor twisted.
. Bleed the brakes.
12.5.3 Pipes
. Fully release the pipe unions (1 Fig. 1).
. Withdraw the pipe (5 Fig. 1) from the vehicle. Plug the
pipes (2 Fig. 1) to prevent the loss of fluid or the ingress of dirt. Thoroughly clean and examine the pipe for signs of damage or deterioration. Renew the pipe if there is any
doubt about its condition.
Thoroughly clean the bore of the pipe using compressed
air.
. Remove all blanking plugs and fit the new pipe to the ve- hicle. Secure the pipe to the body.
. Bleed the brakes.
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Fig. 1
X300 VSM 21 Issue 1 August 1994

12.6 REAR WHEEL SPEED SENSOR - RENEW
SRO
70.60.04
. Drive the vehicle onto a ramp or raise the back and support
on two stands.
. Cut and remove the ratchet strap securing the speed sen- sor harness to the brake hose.
. Undo and remove the speed sensor to hub carrier secur- ing bolt (Fig. 1).
Remove the speed sensor from the hub carrier and allow
it to hang free, forward of the 'A' frame.
Open both rear doors and displace the rear seat cushion
from the seat pan brackets. Reposition the rear seat
cushion forwards.
9 Push the seat belts/ buckles through the seat cushion slots
and remove the rear seat cushion from the vehicle.
. Displace the RH side of the seat pan sound proofing (1 Fig. 2) to gain access to the speed sensor harness (2 Fig. 2).
9 Displace the speed sensor harness grommet (3 Fig. 2) from the seat pan aperture.
. Feed the speed sensor harness through the seat pan aper- ture and disconnect the multi-plug (4 Fig. 2).
9 Position the new speed sensor harness and connect the
multi-plug.
. Feed the speed sensor harness through the seat pan aper- ture to hang free below the vehicle.
. Refit and fully seat the speed sensor harness grommet to
the seat pan aperture.
Reposition theseat pan sound proofing to its original posi- tion.
Position the rear seat cushion and feed the seat belt / buckles through the slots.
Locate the rear seat cushion into the seat pan brackets (5 Fig. 2).
. Stow the seat belts / buckles.
. Position the speed sensor harness rearwards over the 'A'
Fit and tighten the speed sensor to hub carrier securing
Secure the speed sensor harness to the brake hose using
frame
and locate into the hub carrier.
bolt.
a ratchet strap. Trim the ratchet strap. Fig.
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Fig. 2
Issue 1 August 1994 22 X300 VSM
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Brakes
12.7 HYDRAULICCONTROL MODULE- RENEW
SRO 70.60.18
70.60.1
9
Refer to Section 12.4, Brake System Bleeding before carrying out this procedure. Pay particular attention to the warn- ings and cautions relating to brake fluid, cleanliness and cleaning materials.
W: The illustration shows the hydraulic control module of a 6 cyl. vehicle with traction control. Hydraulic control
modules on non-traction control vehicles have only three outlet ports. Apart from this, the removal procedure
is the same for all vehicles.
. Raise the vehicle.
Displace the bleeder screw dust cap of the front LH caliper.
The dust cap will remain captive
on the bleed screw.
. Connect a bleeder tube and bottle to the bleeder screw (1
Fig. 1) and open the bleeder screw.
. Fit a brake pedal hold-down tool (JDS-9013) between the
brake pedal and the steering wheel. Adjust the tool to op
- erate the brake pedal 60mm down. This operation is
necessary to prevent fluid loss from the reservoirthrough
. Re-tighten the front LH caliper bleeder screw. Disconnect
the bleeder tube from the bleeder screw and remove the
tube and bottle. Refit the bleeder screw dust cap.
Undo the securing bolt of the multi-plug connector (1 Fig. 2). The bolt will remain captive. Disconnect the multi-plug
connector and reposition safely.
. Place absorbent material underneath the hydraulic con-
trol module to absorb any spillages.
Undo the tandem master cylinder CTMC) brake pipe gland
nuts (2 Fig.2) and disconnect the brake pipes.
. Fit plugs immediately to the brake pipes and the hydraulic
control module to prevent fluid
loss.
. Undo the rear brake pipe gland nuts (3 Fig. 2) at the pres- sure conscious reducing valves (PCRVs) (4 Fig. 2). Remove
the rear brake pipes.
disconnected brake pipes.
Note: Take necessary steps to prevent rotation of the
PCRVs when removing the rear brake pipes.
Fit plugs immediately to the brake pipes and the PCRVs to
. Undo and remove the PCRVs. Fit plugs immediately to the
Place PCRVs aside to be fitted later to the new hydraulic
. Undo the front brake pipe gland nuts (5 Fig. 2) and remove
. Fit plugs immediately to the brake pipes and the hydraulic
. Undo and remove the three securing nuts (6 Fig. 2) and re-
0 prevent fluid loss.
PCRVs and the hydraulic control module.
control module.
the front brake pipes.
control module to prevent fluid
loss.
move the hydraulic control module. Fia.
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Fia. 2
Issue 1 August 1994 X300 VSM 23

Remove the absorbent material and clean the mounting bracket and surrounding area.
Fit and align a new hydraulic control module to the mounting bracket. Ensure that the mounting cup tangs fully en-
9 Fit and tighten the securing nuts (6 Fig. 1).
. Place absorbent material underneath the hydraulic con- trol module to absorb any spillages.
. Connect the front hydraulic brake pipes (5 Fig. 1) tothe hy- drauliccontrol module, removing plugs immediately prior
to connection. Tighten the gland nuts.
Fit the PCRVs (4 Fig. 1) to the hydrauliccontrol module, re- moving plugs immediately prior to connection. Tighten
the PCRVs.
Connect the rear hydraulic brake pipes (3 Fig. 1) to the
PCRVs, removing the plugs immediately prior to connec- tion. Tighten the gland nuts.
gage
the bracket slots.
&&a: Take necessary steps to prevent rotation of the
PCRVs when fitting the rear brake pipes.
Connect
theTMC hydraulic brake pipes (2 Fig. 1) to the hy- draulic control module, removing the plugs immediately
prior to connection. Tighten the gland nuts.
. Remove the absorbent material and clean thesurrounding
area.
. Reposition and connect the multi-plug connector. Tighten
the securing bolt (1 Fig. 1).
. Ensure that all fixings are torque tightened to specified tol- erances.
. Release the brake pedal hold-down tool and remove.
. Bleed the brake system (refer to sub-section 12.4.4).
. Examine the hydraulic control module for leaks.
3 1 J70 296
Fig. 1
Issue 1 August 1994 ~~ X300 VSM