Hydraulic Brake Actuation Land Rover Range Rover L322

COMPONENT LOCATION

Note. 4.4L V8 vehicle shown, other vehicles similar

Note. right-hand drive (RHD) installation shown, left-hand drive (LHD) installation similar

Scheme 23

OVERVIEW

Hydraulic brake actuation consists of

1. The brake pedal.
2. The brake master cylinder and reservoir.
3. The hydraulic pipes and hoses.

Scheme 24

The brake pedal is mounted in a bracket attached to the rear side of the engine bulkhead. A clevis pin and clip connect the brake pedal to the push rod of the brake booster.

The stop lamp switch is mounted in the brake pedal bracket and operated by the brake pedal.

For additional information, refer to: Anti-Lock Control - Traction Control - 4.2L - Description & Operation

Scheme 25

The master cylinder assembly produces hydraulic pressure to operate the brakes when the brake pedal is pressed. The assembly is attached to the front of the brake servo assembly, and comprises a cylinder containing two pistons in tandem. The rear piston produces pressure for the primary circuit and the front piston produces pressure for the secondary circuit.

When the brake pedal is pressed, the front push rod in the brake servo assembly pushes the primary piston along the cylinder bore. This produces pressure in the primary pressure chamber which, in conjunction with the primary spring, overcomes the secondary spring and simultaneously moves the secondary piston along the cylinder bore. The initial movement of the pistons, away from the piston stops, closes the primary and secondary center valves.

Further movement of the pistons then pressurizes the fluid in the primary and secondary pressure chambers, and thus the brake circuits. The fluid in the chambers, behind the pistons, is unaffected by movement of the pistons and can flow unrestricted through the feed holes between the chambers and the reservoir. When the brake pedal is released, the primary and secondary springs push the pistons back down the bore of the cylinder. As the pistons contact the piston stops, the primary and secondary center valves open, which allows fluid to circulate between the reservoir, through the center valves, the chambers behind the pistons and the feed holes.

The brake fluid reservoir is located on top of the master cylinder assembly. The reservoir is internally divided to provide an independent supply of fluid to each brake circuit, and so prevent a single fluid leak from disabling both primary and secondary brake circuits. Should a failure occur in one circuit, the remaining circuit will still operate effectively, although brake pedal travel and vehicle braking distances will increase.

A fluid level switch is incorporated into the reservoir cap

1. With sufficient fluid in the reservoir the contacts of the fluid level switch are closed.
2. When the fluid level drops below allowable limits, the switch contacts open.

Since the normal position is closed, this circuit is monitored for shorts to + and ground.

The anti-lock brake system (ABS) module monitors the input from the fluid level switch and issues a low fluid level signal to the lighting control module (LCM) on the controller area network (CAN) if the switch opens.

If the low fluid level signal is momentary, the LCM signals the instrument cluster of the condition. The instrument cluster then informs the ABS module over the CAN bus. If the signal is received prior to the activation of the pre-charge pump, the pre-charge pump activation is delayed.

If the signal is present for more then 25 seconds, the LCM issues two I bus messages for the instrument cluster

1. Display CHECK BRAKE FLUID in the message center.
2. Notify the ABS module, via CAN, that the fluid level has been low for more than 25 seconds.

The ABS module immediately switches DSC functions off and sends a CAN signal to the instrument cluster to continuously illuminate the DSC warning indicator.

BRAKE PIPES AND HOSES

The brake pipes and hoses connect the master cylinder to the wheel brakes via the hydraulic control unit. The pipes are arranged to provide a front and rear split braking system. The brakes on the front axle are operated by the primary system; the brakes on the rear axle are operated by the secondary system.

Scheme 26

Scheme 27

1. Disconnect the low brake fluid warning indicator switch electrical connector. Release the wiring harness.
2. Disconnect the pre-charge pump feed hose. Release the clip.
3. Remove the brake fluid reservoir. Release the 2 clips. Remove and discard the 2 seals.

INSTALLATION

1. Install the brake fluid reservoir. Clean the component mating faces. Install the new seals.
2. Connect the pre-charge pump feed hose. Secure the clip.
3. Connect the low brake fluid warning indicator switch electrical connector. Secure the wiring harness.
4. Bleed the brake system. Refer to «Brake System Bleeding - Vehicles With: Standard Brakes»(/land-rover/range-rover/l322-2005-2009/remont/anti-locktraction-control/#brake-system-general-information__brake-system-bleeding-vehicles-with-standard) .

REMOVAL

1. Disconnect the low brake fluid warning indicator switch electrical connector. Release the wiring harness.
2. Disconnect the pre-charge pump feed hose. Release the clip.
3. Remove the brake fluid reservoir. Release the 2 clips. Remove and discard the 2 seals.

1. Install the brake fluid reservoir. Clean the component mating faces. Install the new seals.
2. Connect the pre-charge pump feed hose. Secure the clip.
3. Connect the low brake fluid warning indicator switch electrical connector. Secure the wiring harness.
4. Bleed the brake system. Refer to «Brake System Bleeding - Vehicles With: High Performance Brakes»(/land-rover/range-rover/l322-2005-2009/remont/anti-locktraction-control/#brake-system-general-information__brake-system-bleeding-vehicles-with-high) .

Scheme 28

1. Remove the brake fluid reservoir. See «BRAKE FLUID RESERVOIR - VEHICLES WITH: STANDARD BRAKES»(/land-rover/range-rover/l322-2005-2009/remont/brakes-control-systems/#hydraulic-brake-actuation) .
2. Remove the brake master cylinder. Disconnect the 3 brake pipes. Remove and discard the 2 nuts. Remove and discard the seal.

1. Install the brake master cylinder. Clean the component mating faces. Install a new seal. Tighten the nuts to 26 Nm (19 lb.ft).
2. Connect the brake pipes. Tighten the nuts to 14 Nm (10 lb.ft).
3. Install the brake fluid reservoir. See «BRAKE FLUID RESERVOIR - VEHICLES WITH: STANDARD BRAKES»(/land-rover/range-rover/l322-2005-2009/remont/brakes-control-systems/#hydraulic-brake-actuation) .

1. Remove the brake fluid reservoir. See «BRAKE FLUID RESERVOIR - VEHICLES WITH: HIGH PERFORMANCE BRAKES»(/land-rover/range-rover/l322-2005-2009/remont/brakes-control-systems/#hydraulic-brake-actuation) .
2. Remove the brake master cylinder. Disconnect the 3 brake pipes. Remove and discard the 2 nuts. Remove and discard the seal.

1. Install the brake master cylinder. Clean the component mating faces. Install a new seal. Tighten the nuts to 26 Nm (19 lb.ft).
2. Connect the brake pipes. Tighten the nuts to 14 Nm (10 lb.ft).
3. Install the brake fluid reservoir. See «BRAKE FLUID RESERVOIR - VEHICLES WITH: HIGH PERFORMANCE BRAKES»(/land-rover/range-rover/l322-2005-2009/remont/brakes-control-systems/#hydraulic-brake-actuation) .

Scheme 29

Scheme 30

Scheme 31

1. Remove the headlamp switch. Refer to «Headlamp Switch - Removal and Installation»(/land-rover/range-rover/l322-2005-2009/remont/exterior-lights/#exterior-lighting) .
2. Remove the stoplamp switch. Refer to «Stoplamp Switch»(/land-rover/range-rover/l322-2005-2009/remont/exterior-lights/#exterior-lighting) .
3. Remove the instrument panel access panel. Release the 2 clips.
4. Remove the brake pedal bracket. Release the wiring harness clip. Remove the 4 Torx bolts.
5. Remove the brake pedal clevis pin. Remove the clip.
6. Remove the brake pedal. Remove the nut and bolt.
7. Remove the brake pedal pad.

1. Install the brake pedal pad.
2. Install the brake pedal. Clean the component mating faces. Tighten the nut and bolt to 45 Nm (33 lb.ft).
3. Install the brake pedal clevis pin. Install the clip.
4. Install the brake pedal bracket. Tighten the Torx bolts to 10 Nm (7 lb.ft). Secure the wiring harness.
5. Install the instrument panel access panel. Secure with the clips.
6. Install the stoplamp switch. Refer to «Stoplamp Switch»(/land-rover/range-rover/l322-2005-2009/remont/exterior-lights/#exterior-lighting) .
7. Install the headlamp switch. Refer to «Headlamp Switch - Removal and Installation»(/land-rover/range-rover/l322-2005-2009/remont/exterior-lights/#exterior-lighting) .

Note. The brake pedal, clutch pedal and bracket is serviced as a complete assembly. The procedure to remove and install the assembly is shown in the clutch pedal procedure.

1. Remove the clutch and brake pedal assembly.

1. Install the clutch and brake pedal assembly.

Scheme 32

Scheme 33

1. Disconnect the battery ground cable. Refer to «Specifications»(/land-rover/range-rover/l322-2005-2009/remont/charging-system/#charging-system-general-information__specifications) .
2. Remove the floor console extension. Remove the screw. Release the 2 clips.
3. Remove the driver side closing trim panel. Remove the 3 screws. Disconnect the footwell lamp electrical connector. Release the vehicle diagnostic socket.
4. Remove the driver side footwell duct. Remove the 2 screws.
5. Release the brake booster push rod from the brake pedal. Remove the clip. Remove the pin.
6. Remove the brake pedal and bracket. Disconnect the stoplamp switch electrical connector. Remove and discard the 3 nuts. Reposition the brake booster and brake master cylinder.
7. Remove the stoplamp switch. Release the clip.
8. Remove the stoplamp switch bracket. Remove the 2 nuts and 2 bolts. Remove the brake pedal return spring.

1. Install the stoplamp switch bracket. Install the brake pedal return spring. Tighten the nuts and bolts to 10 Nm (7 lb.ft).
2. Install the stoplamp switch. With the brake pedal released, make sure the stoplamp switch is in contact with the brake pedal.
3. Install the brake pedal and bracket. Reposition the brake booster and brake master cylinder. Tighten the nuts to 26 Nm (19 lb.ft).
4. Secure the brake booster push rod to the brake pedal. Install the pin. Install the clip.
5. Install the driver side footwell duct. Tighten the screws.
6. Install the driver side closing trim panel. Connect the footwell lamp electrical connector. Secure the vehicle diagnostic socket. Tighten the screws.
7. Install the floor console extension. Secure the clips. Tighten the screw.
8. Connect the battery ground cable. Refer to «Specifications»(/land-rover/range-rover/l322-2005-2009/remont/charging-system/#charging-system-general-information__specifications) .

BRAKE PEDAL MOTOR

No Data Available.

See also:
• Anti-Lock Control - Traction Control - 4.2L - Description & Operation
• Brake System Bleeding - Vehicles With: Standard Brakes
• Brake System Bleeding - Vehicles With: High Performance Brakes
• Headlamp Switch - Removal and Installation
• Specifications
• BRAKE FLUID RESERVOIR - VEHICLES WITH: STANDARD BRAKES