Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Adaptive Speed Control


The adaptive speed control system is not a collision warning or avoidance system. At all times the driver must be prepared to intervene to control the vehicle speed.

Adaptive speed control operation is similar to the standard speed control system for engaging, suspending and resuming speed control. The main differences between the two systems is that adaptive speed control remains engaged below 24 km/h (15 mph) and uses the brakes to slow the vehicle, to a halt if necessary.

If adaptive speed control is suspended by pressing the cancel 'CAN' switch, the brake pedal, it can be re-engaged by pressing the resume 'RES' switch once the vehicle speed is above 10 km/h (6 mph).

The adaptive speed control system utilizes the following main components:

  • Adaptive Speed Control Module (ASCM)
  • Right steering wheel switchpack switches
  • ECM
  • Electric throttle
  • Fuel Injectors
  • ABS control module and Hydraulic Control Unit (HCU)
  • Adaptive speed control warning indicator (in the instrument cluster)
  • Forward alert warning indicator.

The adaptive speed control system uses a forward looking radar sensor (integrated in the ASCM) to scan the road ahead, to detect objects that are moving in the same lane. When a target is identified, the adaptive speed control system will monitor the time gap between itself and the target vehicle. When closing in and the adaptive speed control system predicts that the time gap will fall below the set driver selected level, the adaptive speed control system will intervene, slowing the vehicle by backing off the throttle and/or applying the brakes, until the correct gap is attained. The driver can choose between four gap settings, 0.8 1.3 1.8 and 2.3 seconds.

Adaptive speed control is active when the vehicle is moving. Adaptive speed control only functions when a set speed is entered via the operation of the SET '+' switch. The adaptive speed control system only intervenes with the set speed when it detects a slower target vehicle in the host vehicle's path, and then only if it predicts the time gap will be breached.

The ECM, electric throttle and fuel injection control are unchanged from those used for the standard speed control system.

With the ignition ON (ignition mode 6), the ASCM is powered up but no radar transmissions are emitted until the vehicle is in motion.

Speed Control Warning indicator

Speed Control Warning indicator

The speed control warning indicator illuminates when standard speed control or adaptive speed control is engaged.

Adaptive Speed Control System Restrictions

The adaptive speed control system is only intended to provide enhanced speed control in certain restricted conditions. The following illustration shows circumstances where the adaptive speed control system may brake late or unexpectedly. The driver is required to intervene in these situations.

Adaptive Speed Control System Restrictions

  1. Driving on a different line to the vehicle in front
  2. Vehicles that merge into the same lane are only detected once they have moved fully into the lane
  3. On bends in the road there can be issues with detection of the vehicle in front when going into and coming out of a bend
  4. Moving around a stationary vehicle may cause uncertainty regarding which vehicle is being followed
  5. A vehicle in front moving out of your lane may cause uncertainty regarding which vehicle is being followed

On the approach to, or exit from a bend, a target vehicle may be lost or a new target acquired as vehicles ahead change their angular position with respect to the ASCM. On a straight road, if the sensing vehicle is in follow mode below its selected set speed, losing the target vehicle will cause the sensing vehicle to accelerate to this set speed. This acceleration is undesirable either on a bend in the road, or entering a bend in the road when the target is suddenly lost, and in this situation the system inhibits the resumption of the set speed.

Follow Mode

A set speed is selected and this speed is maintained until a slower vehicle is encountered in the lane ahead. When the vehicle ahead comes within the effective range of the ASCM radar, the system identifies it as a target vehicle. To indicate that the system is in follow mode, the follow mode warning indicator illuminates in the IC and the current time gap setting is displayed in the message center. When the distance between the two vehicles closes to the set time gap, the adaptive speed control system reduces engine speed and, if necessary, applies the brakes to maintain the set time gap.

The follow mode can be disabled by pressing and holding the time gap decrease switch on the right steering wheel switchpack, until the follow mode OFF icon is displayed in the Message center.

Follow Mode Warning Indicator

Follow Mode Warning Indicator

Automatic braking is limited to approximately 30% of full pressure (0.3 G deceleration) and is intended to provide a smooth, gradual deceleration in follow mode conditions.

Follow mode is effectively a closed loop system. If several vehicles are ahead, the closest vehicle is chosen as the target to follow. If the target vehicle moves out of the ASCM radar range, or if either vehicle changes lane, the system exits follow mode and extinguishes the follow mode warning indicator. The adaptive speed control system then increases vehicle speed back to the original set speed.

Queue Assist

When adaptive speed control is engaged, if the target vehicle comes to a halt, the ASCM reduces engine speed and applies the brakes to halt the sensing vehicle and suspends speed control operation. The ASCM also applies the Electric Park Brake (EPB) if one of the following occurs:

  • Adaptive speed control is disengaged with the cancel 'CAN' switch
  • The brake pedal is pressed
  • Neutral gear is selected
  • Hill Descent Control (HDC) is selected
  • Automatic Speed Limiter (ASL) is selected
  • The vehicle is stationary for more than 3 minutes
  • Driver exit is detected
  • A system fault is detected.

When the target vehicle moves away, pressing the accelerator pedal for a minimum of 0.2 second (on the flat ground) resumes speed control operation. The sensing vehicle then follows the target vehicle in follow mode or until it stops again, or, if it can no longer detect a target, accelerates back up to the set speed.

Forward Alert

If an object is detected close ahead, a warning tone will be emitted from the IC and a message will be displayed in the message center. The brakes will not be applied.

The forward alert system is active when the warning indicator in the IC is illuminated. Forward alert does not initiate any action, the driver must take the appropriate action when the message is displayed in the message center. The system monitors driver intervention and may not issue the warning if the driver has taken the appropriate action (braking, steering or indicating) early enough.

The sensitivity of the warning can be changed using the gap increase and decrease switches when the adaptive cruise control is not engaged.

Confirmation of the gap change is given in the message center.

Forward Alert Indicator

Forward Alert Indicator

The forward alert warning indicator illuminates if forward alert is enabled in the IC menu.


This system is intended as a driver aid and should be used as such.

The system is NOT a collision warning or avoidance device.


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