VIN Range: M45255->N13088

Speed Control - VIN Range: M45255->N13088

Principles of Operation
There are two types of speed (cruise) control fitted, adaptive cruise control (ACC) and non-adaptive cruise control.

The non-adaptive system maintains a road speed selected by the driver from the steering wheel switches, and is cancelled by inputs from the steering wheel CANCEL switch, the brake pedal (the system will disengage if the brake pedal is pressed), road speed (the system will disengage if the road speed falls below 26 kph [16 mph]), gear selector position (the system will disengage if NEUTRAL, PARK or REVERSE gears are selected), traction or stability control (the system will disengage if the traction or stability control is activated).

The adaptive system also maintains a road speed selected by the driver from the steering wheel switches, and is cancelled by the same inputs (the only difference being that the selected speed will show in the message center display), but can also maintain a selected distance from the vehicle in front.

When the system is enabled, the vehicle will maintain the selected speed until another vehicle is detected travelling in the same lane and direction, when it will enter FOLLOW MODE.

In this mode, the vehicle will maintain a time gap from the vehicle in front, rather than the selected speed. This is not a fault, but a designed feature of the system. The time gap is adjustable, using the HEADWAY switches on the steering wheel switchpack, but will default to a longer gap, unless overridden by the driver.

When the vehicle enters FOLLOW MODE, the message center will display the ACC tell-tale symbol (see the owner's handbook), with a GAP indication for four seconds, and the vehicle will maintain the gap from the vehicle in front until;
- The vehicle in front accelerates to a speed above the selected speed, in which case the selected speed will be resumed
- The vehicle in front moves out of lane, or out of view, in which case the selected speed will be resumed
- The vehicle in front slows to below 26 km/h (16 mph), at which speed the system disengages, the message DRIVER INTERVENE will display on the message center, and any braking applied by the ACC system will reduce. This is not a fault but may involve the driver having to take control and brake him/herself.
- A new gap distance is set by the driver from the steering wheel switches

The ACC system can apply the brakes to maintain the gap to the vehicle in front. The braking force which the system can apply is limited, but can be overridden by the driver braking. This action will cancel the cruise control function, but the system will "remember" the selected speed, and will resume the selected speed by the driver pressing the RESUME switch on the steering wheel switchpack

NOTE: When the system applies the brakes, the brake lights will function exactly as if the driver were braking.

It is possible (for example, when a slow-moving vehicle pulls out into the lane in front), for the degree of braking necessary to avoid a collision to exceed the maximum level of the ACC system. Should this happen, an audible warning will sound, accompanied by a red warning light and a DRIVER INTERVENE display on the message center, at which point, the driver must take action. This is not a fault, but a designed feature of the system.

Should the driver need to go faster than the selected speed, he/she can override the system simply by pressing the accelerator, in which case, the message center will display CRUISE OVERRIDE. When the pedal is released, the system will resume operation in whichever mode is appropriate, follow or selected speed.

Detection
As with most sensors, there are certain conditions under which detection issues can occur. The owner/driver's attention should be drawn to the driver's handbook to avoid misunderstandings as to what is, and isn't, a fault.

Detection issues may occur;
- When driving on a different line to the vehicle in front
- When vehicles edge into your lane
- When going into or coming out of a bend
- With detecting motorcycles
- With detecting stationary objects, such as traffic queues, broken down vehicles, etc

In circumstances such as these, the ACC system may brake late or unexpectedly, or may increase speed. This is not a fault, but is the system reacting to detection issues.

The owner's handbook makes it clear that the system should only be used under suitable conditions, but technicians should be wary of wasting time on complaints which are not actually faults.