VIN Range: G45704->G99999
Speed Control - VIN Range: G45704->G99999
Speed Control - VIN Range: G45704->G99999:
System operation
The speed control system is inoperative below 32 kph (20 mile/h) and above 250 kph (155 mile/h).
The speed control system is designed to maintain a selected vehicle speed between 32 kph (20 mile/h) and 180 kph (112 mile/h).
Any of the switches operated by the brake will interrupt the speed control operation by switching the signal to the engine control module (ECM). This will allow the system to go into STANDBY mode. Pressing the RESUME switch with the vehicle travelling above 32 kph (20 mile/h) while the system is in STANDBY mode will allow the vehicle to accelerate until the last set speed is resumed.
Speed Control Steering Wheel Switches
RESUME Switch
When the RESUME switch is operated with the vehicle travelling above 32 kph (20 mile/h) with the system in STANDBY mode, the vehicle is allowed to accelerate until the last set speed is resumed. The RESUME switch will not function if the ignition switch has been cycled or if the vehicle speed is below 32 kph (20 mile/h).
CANCEL Switch
When the CANCEL switch is operated with the vehicle travelling above 32 kph (20 mile/h) the system will enter STANDBY mode.
SET Switch
When the SET +/- switch is operated with the vehicle travelling above 32 kph (20 mile/h) the system allows the vehicle speed to be maintained to ± 1.62 kph (1 mile/h). Pressing the SET +/- switch will increase or decrease the vehicle speed respectively until the switch is released. If the respective switch is pressed momentarily, the speed will accelerate or decelerate in 1.62 kph (1 mile/h) increments.
Brake Pedal Position (BPP) Switch
If the brake pedal is operated while the speed control system is active, the ECM receives a signal from the BPP switch. This will cancel vehicle speed control and allow the throttle blade to return to the position as demanded by the accelerator pedal.
Speed Control Deactivation Switch (brake).
If the brake pedal is activated while the speed control system is active, the ECM receives a signal from the speed control deactivation switch. This will cancel speed control and allow the throttle blade to return to the position as demanded by the accelerator pedal.
Adaptive Speed
Control On vehicles for certain markets, an adaptive speed control system is installed as an option. In addition to the normal vehicle speed control functions, this system enables a preset distance to be maintained behind a moving vehicle immediately ahead, without driver intervention.
Automatic Switch Off - Vehicles with Adaptive Speed Control
The adaptive speed control will disengage, but not clear the memory when:
- the CANCEL button is operated.
- the brake pedal is applied.
- the vehicle speed falls below 26 kph (16 mile/h).
- neutral, park or reverse gear positions are selected.
- traction control is activated.
- cruise override activated for more than five minutes.
The adaptive speed control will disengage, and clear the memory when:
- the ignition switch is set to position '0'.
- a fault occurs in the adaptive speed control system.
Forward Alert Switch - Vehicles with Adaptive Speed Control
Forward Alert
The forward alert system is switched on and off by the forward alert switch, which is incorporated into the message center switch. The forward alert system additionally provides warnings while the adaptive speed control is not activated.
Speed Control Module - Vehicles with Adaptive Speed Control
The speed control module provides system control functions.
Speed Control Sensor - Vehicles with Adaptive Speed Control
The speed control sensor incorporates the forward looking radar sensor.
Adaptive Speed Control Failure
If a fault occurs during any adaptive speed control operation, the adaptive speed control system will deactivate and will remain in this state until the fault is rectified. The 'CRUISE NOT AVAILABLE' message will be displayed on the message center on 'demand' by trying to operate the steering wheel control switches. This on 'demand' strategy is intended to show that adaptive speed control is not available and another fault may exist. For example: If an anti-lock brake system or traction control error message is displayed this would imply that the brake system may be effecting or inhibiting the adaptive speed control. If the message center displays 'CRUISE NOT AVAILABLE' permanently or no message is displayed, this may imply that the vehicle has an ECM fault.
Automatic Speed Limiter
The automatic speed limiter enables the vehicle speed to be limited. The vehicle speed is selected from the message center, the ECM limits the throttle response and stops the vehicle from accelerating over the preset speed limit.
NOTE:
- Automatic speed limiter is restricted to controlling the throttle only.
- Automatic speed limiter is unable to request automatic braking.
Automatic Speed Limiter Switch
Vehicles fitted with an automatic speed limiter are fitted with an automatic speed limiter master switch. This switch is intended for use as an automatic speed limiter ON/OFF switch, it also functions as a selection switch between adaptive/normal speed control and the automatic speed limiter options.
- If the automatic speed limiter is selected the adaptive/normal speed control is cancelled.
- If the automatic speed limiter is NOT selected the adaptive/normal speed control can be used.
- The automatic speed limiter switch will be a standard fit to all XJ variations.
- The automatic speed limiter switch is illuminated when switched on.
Cruise switches
Existing speed control; switch pack is used for automatic speed limiter.
- Set +/- switch.
- Resume switch.
- Resume switch.
- Cancel switch.
- When adaptive speed control is fitted, the headway switches have no affect on automatic speed limiter.
Message center
Automatic Speed Limiter Messages
The automatic speed limiter will keep the driver informed of it's status by displaying messages in the message center.
Activation of the Automatic Speed Limiter
- The driver has the ability to change trip units, which will make the display speed change in increments of 2 kph or 1 mile/h.
- The automatic speed limiter can be set using the set +/- switch to the nearest 2 kph (1 mile/h) depending on the drivers selected trip units.
- The automatic speed limiter can be ramped up to major increments of 10 kph or 5 mile/h depending on the drivers selected trip units.
- The automatic speed limiter has a minimum set speed of approximately 32 kph (20 mile/h).
- The automatic speed limiter will stay active and not cancel if the vehicle speed falls below the minimum set speed.
Maximum Operating Speed of the Automatic Speed Limiter
Engine Maximum Speed
3.0L 249 kph (155 mile/h)
3.5L 249 kph (155 mile/h)
4.2L 249 kph (155 mile/h)
4.2L Supercharged 249 kph (155 mile/h)
Cancellation of the Automatic Speed Limiter
The following three actions will cause the automatic speed limiter to cancel.
- Cancel switch.
- Accelerator kick down.
- De-selection by the master switch.
Service Issues
Limiter Not Available
It is difficult to get 'LIMITER NOT AVAILABLE' without a 'CRUISE NOT AVAILABLE' or a throttle malfunction. The automatic speed limiter is designed to limit the throttle and it is therefore very difficult to make the feature fail.
The automatic speed limiter shares the master ON/OFF switch and cruise switches with the speed control/adaptive speed control. Any failure will inhibit the speed control/adaptive speed control as well as automatic speed limiter.
Over speed down hill
The automatic speed limiter does not have any brake assistance, this means automatic speed limiter will over speed on down hill gradients.
The message center will display over speed warnings if the pre set thresholds have been exceeded. This is the intended functionality.
When message center provides the driver with over speed warnings; it is the driver's responsibility to apply the brakes.
Ramp down of set speed
The driver has the ability to ramp down the set speed i.e. transition from 96.5 kph (60 mile/h) to 48.2 kph (30 mile/h) zone.
Automatic speed limiter is not able to apply the brakes. The vehicle will be slowed down by engine braking ONLY.
The message center will display over speed warnings if the preset thresholds have been exceeded. This is the intended functionality.
When message center provides the driver with over speed warnings; it is the driver's responsibility to apply the brakes.
Differences between Diesel and Petrol Automatic Speed Limiter
Set Events
The diesel automatic speed limiter is set by holding the set + switch for a specific (approximately 400ms) period of time.
The petrol automatic speed limiter is set by pressing and releasing the set + switch.
Automatic Speed Limiter, CC and ACC Tolerances
- Both the adaptive speed control and the automatic speed limiter display a 'set speed' to the driver. This 'set speed' should match the speedometer, however it is acceptable for it to be within a tolerance of one increment +/- 1 kph (0.5 mile/h).
- When switching between the automatic speed limiter and adaptive speed control functions there may be a difference in speed of +/- 2 kph or +/- 1 mile/h, this is acceptable due to both speeds being calculated on different modules. If the difference is greater than 4 kph or 2 mile/h there may be a configuration issue.
- The ECM calculates the displayed speed for the automatic speed limiter.
- The ACC module calculates the display speed for the adaptive speed control.
- The speedo and set speed tolerance region will be approximately between 48 kph (30 mile/h) and 145 kph (90 mile/h). The speedometer may not match the set speeds when travelling in excess of 145 kph (90 mile/h), this is acceptable.