Description

Parking Brake

NOTE:
A = Hardwired; D = High speed CAN (controller area network) bus.









When the parking brake is applied with the EPB (electronic parking brake) switch, the EPB (electronic parking brake) module uses the wheel speed inputs from the ABS (anti-lock brake system) module to determine when to use the static and dynamic modes of operation. It uses the static mode at vehicle speeds up to 2 mph (3 km/h) and the dynamic mode at vehicle speeds greater than 2 mph (3 km/h).

STATIC APPLY/RELEASE
For the static apply to operate, the ignition can be on or off. When the EPB (electronic parking brake) switch is pulled up, the EPB (electronic parking brake) module activates both EPB (electronic parking brake) actuators to apply the brakes and signals the instrument cluster to turn on the red parking brake warning indicator. The warning indicator remains on continuously while the ignition is on, and for 10 seconds after the ignition goes off.
For the static release to operate, the ignition must be on and the brake pedal pressed. When the EPB (electronic parking brake) switch is pressed down, the EPB (electronic parking brake) module then activates both EPB (electronic parking brake) actuators to release the brakes and signals the instrument cluster to turn off the red parking brake warning indicator.

GRADIENT DEPENDANT APPLY
For all static apply modes, the EPB (electronic parking brake) module varies the clamp load applied by the EPB (electronic parking brake) actuators depending on the gradient the vehicle is on. On gradients of less than 10% a reduced clamp load of 13.5 kN is applied. On gradients of 10% and above the nominal clamp load of 16.5 kN is applied.
Gradient dependant apply is inhibited, and the nominal clamp load of 16.5 kN applied on gradients of less than 10%, if the EPB (electronic parking brake) switch is held in the apply position for more than 3 seconds.

IGNITION OFF APPLY
The EPB (electronic parking brake) is automatically applied when the ignition is switched off.
The EPB (electronic parking brake) module inhibits the ignition off apply operation if the EPB (electronic parking brake) switch is held down, the ignition is turned off within 5 seconds, and the EPB (electronic parking brake) switch is then held down for a further 2 seconds.

DRIVE AWAY RELEASE
With the vehicle static and the parking brake applied, the DAR (drive away release) mode gradually reduces the clamp load when the accelerator pedal is pressed, without the EPB (electronic parking brake) switch being set to the release position, to assist with a smooth drive away. This mode is only active if either the driver door is closed, or if the driver safety belt is buckled and the engine is running.
The point at which the EPB (electronic parking brake) module releases the brakes is determined by the following factors:
- Tilt angle - from the inclination sensor in the EPB (electronic parking brake) module.
- Engine torque - from the ECM (engine control module).
- Throttle pedal applied - from the APP (accelerator pedal position) sensor.
- Clutch pedal releasing - from the clutch position sensor (manual transmission vehicles).
- 1st or reverse gear selected - from the 1st and reverse gear switch (manual transmission vehicles).
- D (drive) or R (reverse) selected - from the TCM (transmission control module) (automatic transmission vehicles).
DAR operation can be delayed by holding the EPB (electronic parking brake) switch in the applied position, then releasing it at the required time.

AUTOMATIC TRANSMISSION APPLY/RELEASE
The parking brake is automatically applied on vehicles with automatic transmission when P (park) is selected.
The parking brake is automatically released when the transmission selector is taken out of P, provided either the driver door is closed, or the driver safety belt is buckled, the brake pedal is applied and the engine is running.

HIGH TEMPERATURE RE-CLAMP
After heavy use of the brakes the disc temperatures can be extremely high. At high brake disc temperatures, if the vehicle is stationary and the parking brake is applied, the EPB (electronic parking brake) module automatically re-applies the parking brake as the brake discs cool down. A temperature model in the EPB (electronic parking brake) module software calculates the brake disc temperature from brake application force, the time the brake force is applied and vehicle speed.
High temperature re-clamp occurs at brake disc temperatures of 300 °C (572 °F) and above. Depending on the temperature up to three re-clamps can occur, at varying time intervals, in the 10 minutes following the initial application of the parking brake. To limit the number of re-clamps, the ignition status as well as the current inclination of the vehicle is considered. If the ignition is on, a re-clamp will only be performed if the vehicle inclination is greater than 10%.

DRIVER EXIT WARNING
If the driver attempts to exit the vehicle with the parking brake off and the ignition on or the engine running, the following warning signals occur when the driver door opens:
- The red parking brake warning indicator illuminates.
- A warning chime sounds.
- A message center warning is displayed.

ROLL AWAY DETECTION
The parking brake is automatically applied if the vehicle is stationary with the parking brake off and then begins to move without operation of the accelerator or clutch pedal(s), indicating there is no driver intention to pull away.

DYNAMIC APPLY
While the vehicle is moving, the dynamic apply mode provides emergency braking. At a vehicle speed greater than 2 mph (3 km/h), pulling up and holding the EPB (electronic parking brake) switch produces a gradual deceleration of the vehicle. The red parking brake warning indicator illuminates, accompanied by a warning in the message center and a warning chime. The vehicle stop lamps also illuminate, activated by a CAN (controller area network) bus message from the EPB (electronic parking brake) module to the CJB (central junction box). Dynamic apply operation is cancelled if the EPB (electronic parking brake) switch is either released or pressed down to the release position, or the accelerator pedal is pressed.
There are four modes of dynamic apply, which the EPB (electronic parking brake) module uses in the following order of preference:
- ECD (electronic controlled deceleration).
- RWU (rear wheel unlocker).
- DSD (dynamic standstill detection).
- DSD+.
The ECD mode uses hydraulic braking on all four wheels to decelerate the vehicle. The other three modes all use the EPB (electronic parking brake) actuators to operate the rear brakes to decelerate the vehicle.

ECD
The braking operation is controlled by the ABS (anti-lock brake system) module, in response to a request from the EPB (electronic parking brake) module on the high speed CAN (controller area network) bus. The ABS module monitors the deceleration rate using the wheel speed sensor signals, and adjusts the hydraulic pressure to the brakes as necessary to achieve the required deceleration. All of the anti-lock control - traction control system brake modes remain enabled. As the vehicle comes to a halt, the hydraulic pressure is reduced to zero and the EPB (electronic parking brake) module applies the parking brake with the EPB (electronic parking brake) actuators.

RWU
The RWU mode is used if the ABS (anti-lock brake system) module cannot operate the brakes or achieve a minimum deceleration rate, but still supplies wheel speed signals to the EPB (electronic parking brake) module. The wheel speed inputs allow the EPB (electronic parking brake) module to adjust the clamp load on the rear brakes as necessary to produce maximum deceleration without locking the wheels. When vehicle speed decreases to 2 mph (3 km/h), the EPB (electronic parking brake) module fully applies the parking brake.

DSD
The DSD mode is used if the ABS (anti-lock brake system) module cannot operate the brakes or achieve a minimum deceleration rate, and the EPB (electronic parking brake) module has no valid wheel speed signals. In the DSD mode, the EPB (electronic parking brake) module uses the G sensor to monitor deceleration. To maintain vehicle stability, the EPB (electronic parking brake) module initially applies a low clamp load to the brakes, then increases the clamp load in steps. When the G sensor signal indicates the vehicle has stopped, the EPB (electronic parking brake) module fully applies the parking brake.

DSD+
The DSD+ mode is used if the ABS (anti-lock brake system) module cannot operate the brakes or achieve a minimum deceleration rate, the EPB (electronic parking brake) module has no valid wheel speed signals and the G sensor has failed. In the DSD+ mode, the EPB (electronic parking brake) module applies a clamp load calculated to give a steady rate of deceleration without locking the wheels.

SERVICE

Functional Test
The EPB (electronic parking brake) module incorporates a vehicle inspection mode that allows a functional test of the parking brake to be performed on a rolling brake tester. For additional information, refer to: Parking Brake and Actuation (206-05, General Procedures).

Brake Pad Replacement
To change the rear brake pads it is necessary to fully retract the thrust nut to allow retraction of the caliper piston. This can be done using one of the following methods:
- Putting the EPB (electronic parking brake) module into the maintenance mode using Land Rover approved diagnostic equipment.
- Putting the EPB (electronic parking brake) module into the maintenance mode without diagnostic equipment.
- Using a special tool to mechanically retract the brake pads.
For additional information, refer to Brake Pads Rear Disc Brake Pads

ELECTRIC PARKING BRAKE SWITCH









The parking brake is manually applied and released using the EPB (electronic parking brake) switch, which is located in the floor console, on the driver side of the gear selector. Pulling the switch lever upwards applies the parking brake. Pushing the switch lever down releases the parking brake.
The resistive ladder type switch has four hardwired connections with the EPB (electronic parking brake) module, consisting of two apply circuits and two release circuits. This enables the EPB (electronic parking brake) module to perform a plausibility check on each switch selection.

ELECTRONIC PARKING BRAKE ACTUATORS









The EPB (electronic parking brake) actuators are electro mechanical positioning units attached to the calipers of the rear brakes. Each actuator incorporates a reversible electric motor driving an output shaft via a drive belt and planetary gear cluster.
The output shaft of the EPB (electronic parking brake) actuator is engaged in the splined end of a spindle, which is inside the caliper piston and screwed into a thrust nut. Operation of the electric motor turns the spindle and produces linear movement of the thrust nut, to apply a target clamp load to the brake pads.

Spindle and Thrust Nut









Two flat surfaces on the inside of the caliper piston prevent the thrust nut from turning with the spindle. Scallops around the circumference of the thrust nut allow the free flow of hydraulic fluid around the nut during mechanical operation by the parking brake system and hydraulic operation by the brake pedal or ABS (anti-lock brake system) module.
Operation of each EPB (electronic parking brake) actuator is controlled by the EPB (electronic parking brake) module via two hardwired connections with the electric motor. The EPB (electronic parking brake) module changes the polarity of the connections to change the direction of drive of the motor.
In each EPB (electronic parking brake) actuator, when the parking brake is applied the electric motor turns the spindle to press the thrust nut against the caliper piston and apply the brake. The EPB (electronic parking brake) module measures the current draw of the electric motor and disconnects the power supply when it equates to a clamp load of 13.5 to 16.5 kN being applied by the thrust nut.
When the parking brake is released, the electric motor turns the spindle for approximately 800 milliseconds to retract the thrust nut and release the pressure on the caliper piston.

CLUTCH POSITION SENSOR (MANUAL TRANSMISSION VEHICLES ONLY)





The clutch position sensor provides the EPB (electronic parking brake) module with a continuous measure of clutch pedal position.
The clutch position sensor is attached to the clutch master cylinder. The sensor is a PCD (permanent magnet linear contactless displacement) type sensor.
The signal from the clutch position sensor is transmitted on a hardwired connection to the CJB (central junction box), which then transmits it to the EPB (electronic parking brake) module on the high speed CAN (controller area network).
To check the plausibility of the input from the sensor, the EPB (electronic parking brake) module uses the inputs from the top of travel switch and the bottom of travel switch in the clutch system. For additional information, refer to Clutch Controls

ELECTRONIC PARKING BRAKE MODULE





The EPB (electronic parking brake) module is located behind the LH (left-hand) rear quarter trim panel in the loadspace.
The EPB (electronic parking brake) module controls the two EPB (electronic parking brake) actuators using a dual micro controller to provide separate control transmission for each actuator. An inclination sensor and a G (gravity) sensor are integrated into the EPB (electronic parking brake) module. The inclination sensor allows the EPB (electronic parking brake) module to determine the longitudinal attitude of the vehicle. The G sensor allows the EPB (electronic parking brake) module to monitor vehicle deceleration.
Separate battery power feeds for the EPB (electronic parking brake) actuators are supplied to the EPB (electronic parking brake) module from the RJB (rear junction box). A further power feed is supplied to the EPB (electronic parking brake) module from the ignition relay in the CJB (central junction box).
Four hardwired connections with the EPB (electronic parking brake) switch provide the EPB (electronic parking brake) module with parking brake apply and release inputs. Inputs from other components are received on the high speed CAN (controller area network), as follows:
- Wheel speed sensors, from the ABS (anti-lock brake system) module.
- APP (accelerator pedal position) sensor, from the CJB (central junction box).
- Stoplamp switch, from the CJB (central junction box).
- Clutch position sensor, from the CJB (central junction box) (manual transmission vehicles only).
- Reverse gear switch, from the CJB (central junction box) (manual transmission vehicles only).
- Gear position, from the TCM (transmission control module) (automatic transmission vehicles only).
- 1st gear switch, from the ECM (engine control module) (manual transmission vehicles only).
- Neutral sensor, from the ECM (engine control module) (manual transmission vehicles only).
In addition to the hardwired outputs to the EPB (electronic parking brake) actuators, the EPB (electronic parking brake) module outputs status and fault signals on the high speed CAN (controller area network) to operate the warning indicators and advise other systems if there is a fault with the EPB (electronic parking brake) system.

WARNING INDICATORS









A parking brake warning indicator in the message center can be illuminated red or yellow. The EPB (electronic parking brake) module operates the warning indicator using high speed CAN (controller area network) messages to the instrument cluster. When the parking brake is applied in the static mode, the warning indicator is permanently illuminated red while the ignition is on, and for 10 seconds after the ignition is goes off. If a fault is detected while the parking brake is applied, the warning indicator flashes red. If a fault is detected while the parking brake is released, the warning indicator flashes yellow. All fault indications are accompanied by a related message displayed in the message center and a warning chime.