Adaptive Speed Control Module
Component Location
Component
| ITEM | DESCRIPTION |
|---|---|
| 1 | Mounting bracket |
| 2 | Electrical connector |
| 3 | Adaptive Speed Control Module (ASCM) |
The Adaptive Speed Control Module (ASCM) is located behind the front grille.
The ASCM contains a forward looking radar transceiver together with related controlling hardware and software. A High Speed (HS) Controller Area Network (CAN) chassis systems bus connection allows the ASCM to communicate with other system control modules. Power supplies to the ASCM are from the extended ignition relay in the Rear Junction Box (RJB).
The ASCM is active whenever the ignition is ON (Power Mode 6), even if speed control is not engaged. The 'Forward Alert', Advanced Emergency Brake Assist (AEBA) and Intelligent Emergency Braking (IEB) functions also use the ASCM. With the ignition ON (Power Mode 6), the ASCM is electrically powered, but no radar transmissions are emitted until the vehicle starts moving.
The ASCM transmits a radar beam forward of the vehicle and detects the returning signals reflected off other vehicles and objects ahead. The radar beam is electronically scanned in 7 zones across a total arc of 30° centered on the longitudinal axis of the vehicle. The vertical coverage of ±5° from nominal position. The radar operates at millimetric wavelengths (76 - 77 GHz). The radar transmits a frequency modulated continuous wave signal at a relatively low power level (no high power pulses). The ASCM detects:
- The range
- The relative velocity
- The angle of objects,
within the scanned arc for up to a maximum distance of 150 meters (500 feet).
The ASCM compares vehicle speed data from the Anti-lock Brake System (ABS) control module with the relative speed of an external object. The speed of the objects is detected by the radar to determine that the object is stationary or not. If tires are equipped which are different in diameter from those specified for the vehicle it may cause an incorrect road speed to be calculated. The ABS control module calculates the vehicle speed. This situation may cause stationary objects to be falsely identified as moving vehicles. The detection of falsely moving vehicles may result in the speed of the sensing vehicle decreasing.
The ASCM continuously monitors both moving vehicles and stationary objects to determine if it can 'see' normally. If the ASCM detects a few objects, or a few roadside objects or other vehicles in the area, it may determine that it is blocked. For example, by an accumulation of snow or mud on the lower grille of the front bumper, or an incorrectly located license plate. The ASCM then inhibits adaptive speed control and records a Diagnostic Trouble Code (DTC). The system will reset after an ignition cycle. In this case the ASCM does not have a fault and should not be replaced.
The ASCM does not require mechanical vertical alignment if it is replaced in service. Horizontal alignment is achieved by putting the ASCM into service mode using the Jaguar Land Rover (JLR) approved diagnostic equipment. The vehicle then needs to be driven for a short period while the ASCM does a calibration routine. Calibration is complete when the 'Follow Mode' warning indicator in the Instrument Cluster (IC) stops flashing.
The service alignment process measures the path of stationary targets for example streetlights, railings, road signs, and parked vehicles. The service alignment process uses this data to correct for radar misalignment.
Alignment will complete more quickly if more suitable targets are seen.
The following recommendations will help:
- The speed must be above 48 km/h (30mph).
- Try to keep the speed constant. The process will take longer to complete if the speed is not constant.
- Choose a road with plenty of stationary objects, like lamp posts, railings, street signs or parked vehicles. Use an inside or outside lane.
- Following vehicles too closely will obscure the stationary targets from the radar, a time gap of at least 2 seconds is recommended.