Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Adaptive Speed Control Brake System Functions

Advanced Emergency Brake Assist (AEBA)

Advanced Emergency Brake Assist (AEBA) improves braking response during emergency braking, and is an enhancement of the electronic brake prefill and emergency brake assist functions controlled by the ABS control module.

For additional information, refer to: Anti-Lock Control - Traction Control (206-09B Anti-Lock Control - Traction Control, Description and Operation).

With AEBA, if the risk of a collision increases after the vehicle passes the forward alert activation threshold, the ASCM signals the ABS control module to activate the electronic brake prefill and emergency brake assist functions. With AEBA, the electronic brake prefill function operates in two stages:

Stage 1:

  • Applies a brake pressure of approximately 3 bar (43.5 lbf/in²) to all of the brakes
  • Lowers the AEBA activation threshold in the ABS control module
  • Signals to the CJB on the HS CAN Powertrain bus to activate the stop lamps.

Stage 2:

  • increases the brake pressure to approximately 10 bar (145 lbf/in²).

Stage 1 is activated if the collision risk increases to a level considered as credible, with the accelerator pedal pressed.

Stage 2 is activated when the accelerator pedal is released during an imminent risk of collision. If the accelerator pedal has already been released when the collision risk increases to the credible level, the two stages of electronic brake prefill are activated simultaneously, to give an immediate brake pressure of 10 bar (145 lbf/in²).

While the second stage of electronic brake prefill is active, if the brake pedal is then pressed quickly, the ABS control module activates AEBA, even if only light pressure is applied to the pedal.

AEBA is available at vehicle speeds above 7 km/h (5 mph) and will function even when forward alert and adaptive cruise control are switched off.

If a fault occurs in the system, a related message is displayed in the message center. AEBA will not be available until the fault is rectified.

Intelligent Emergency Braking (IEB)

Intelligent emergency braking (IEB) reduces the impact velocity if the ASCM determines that a collision is unavoidable, even with driver intervention. It is not designed to prevent accidents from occurring. Typical activation of IEB is approximately 0.8 second before impact. During this 0.8 second period the speed of the sensing vehicle is reduced, thus reducing the impact energy.

If the ASCM determines a collision is unavoidable, it signals the ABS control module to apply emergency brake pressure to all of the brakes. On vehicles without active safety belts, emergency brake pressure is 50 bar (725 lbf/in²) maximum. On vehicles with active safety belts, emergency brake pressure is 100 bar (1450 lbf/in²) maximum.

When IEB is initiated the ASCM also signals the Restraints Control module (RCM) to fire the front seatbelt retractors.

For additional information, refer to: Seatbelt System (501-20A Seatbelt System, Description and Operation).

After the IEB function has activated, it is then disabled, as the vehicle is assumed to be damaged. After the vehicle has been repaired, the IEB function can be re-enabled using Land Rover approved diagnostic equipment.

The IEB function operates down to a vehicle speed of 10 km/h (6mph), and will function even when forward alert and adaptive cruise control are switched off.

If the IEB feature is disabled for any reason, a related message is displayed in the message center.

CONTROL DIAGRAM

CONTROL DIAGRAM - STANDARD SPEED CONTROL

NOTE:

A = Hardwired; O = LIN Bus; AN = High speed CAN powertrain systems bus

CONTROL DIAGRAM - STANDARD SPEED CONTROL

  1. Engine Control Module (ECM)
  2. Right steering wheel switchpack
  3. Clockspring
  4. Body Control Module (BCM)
  5. Transmission Control Module (TCM) - vehicles with automatic transmission only
  6. Instrument Cluster (IC)
  7. Anti-lock Brake System (ABS) control module
  8. Ground
  9. Fuse 5A - located in Battery Junction Box (BJB)
  10. Ignition relay - located in BJB

CONTROL DIAGRAM - ADAPTIVE SPEED CONTROL

NOTE:

A = Hardwired; O = LIN Bus; AN = High speed CAN powertrain systems bus

CONTROL DIAGRAM - ADAPTIVE SPEED CONTROL

  1. Adaptive Speed Control Module (ASCM)
  2. Right steering wheel switchpack
  3. Clockspring
  4. Body Control Module (BCM)
  5. Engine Control Module (ECM)
  6. Transmission Control Module (TCM) - vehicles with automatic transmission only
  7. Instrument Cluster (IC)
  8. Anti-lock Brake System (ABS) control module
  9. Ground
  10. Fuse 5 A - located in Battery Junction Box (BJB)
  11. Ignition relay - located in BJB
  12. Fuse 5 A - located in CJB
  13. Ignition relay - located in CJB

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