Part 3

A triggering factor is needed for self-induced oscillations to arise, for example:
- vehicle with trailer is exposed to sudden forceful sidewind
- vehicle with trailer is driven on uneven road or on a bump
- sweeping steering wheel movements.
Trailer stability assistance (TSA) continuously monitors the car's movement, especially sideways. If self-induced oscillations occur, individual brake control takes place on the wheels, having a stabilizing effect on the vehicle. Often this is enough to regain control of the vehicle. If self-induced oscillations are not reduced, the vehicle is braked on all wheels combined with reduction of the engine's drive power. During this phase, normally the brake lights are on, this is determined by how 'big' the braking is. When self-induced oscillations have stopped and the vehicle is stable once again, trailer stability assistance stops its control and the driver regains full control of the car.
Actions from trailer stability assistance (TSA) may not occur if the driver tries to counteract self-induced oscillations with forceful steering wheel movements, since trailer stability assistance (TSA) cannot decide if it is the driver or the trailer that is causing the self-induced oscillations. Trailer stability assistance (TSA) can act in the speed range 60-160 km/h.
When trailer stability assistance (TSA) is working the DSTC-symbol flashes in the combination instrument.

Brake function requested by other systems
In the Mark 25E1 brake system, other vehicle control systems can send a request for the brake system to perform certain brake functions.
Forward Sensing Module (FSM)
The forward sensing module (FSM) regulates a system that uses a forward-aimed radar to detect whether there are any objects within a predefined area in front of the vehicle. If an object is registered, a request is sent to the brake control module (BCM) for automatic braking.
The system comprises two subfunctions: adaptive cruise control (ACC) ands collision warning and collision mitigation by braking.
Adaptive cruise control is a function that operates when cruise control is active. It helps the driver check and maintain the distance to the vehicle directly in front. If the radar of the forward sensing module (FSM) detects an object nearing a predefined area at the front of the vehicle, the control module sends a request to the brake control module (BCM) to gently decelerate the vehicle. The function is enabled and disabled via the control for cruise control.
Collision warning and collision mitigation by braking is a function that helps the driver obtain maximum braking effect when there is a risk of collision. If the radar of the forward sensing module (FSM) detects that an object in front of the vehicle is within a predefined area, the control module sends a request to the brake control module (BCM) to increase preparedness. The brake control module (BCM) increases brake pressure as a means of preparing to help the driver brake. If collision is unavoidable, the brake control module (BCM) automatically helps the driver obtain maximum brake effect.
The adaptive cruise control and the collision warning and collision mitigation by braking functions are not triggered if there is a fault in the brake control module (BCM) or if the central electronic module (CEM) indicates that there is a fault in one of these functions via the CAN network.
For a more detailed description of the systems, see Design and Function, Forward Sensing Module (FSM).
Closing velocity module (CVM)
Closing velocity module (CVM) controls the system for safe driving in city traffic using a lidar which during travel at low speeds helps the driver within a predefined area. If an object is registered, a request is sent to the Brake control module (BCM), for automatic braking. The system is included in a function called City Safety.
City Safetyis a function that helps the driver to automatically brake the vehicle at high collision risk at speeds below 30 km/h.
The function is intended for stationary vehicles and vehicles moving in the same direction as the own vehicle. Thus, the function does not react to on-coming vehicles.
The function is primarily intended to help drivers who for some reason are distracted and do not have full concentration on traffic in front of the own vehicle. If the driver is considered active since he steers, throttles, or brakes heavily, the City Safety will not brake automatically.
The function works by Closing velocity module (CVM), located behind the rearview mirror, using a laser sensor and registers any traffic in front of the vehicle. In case of major collision risk the Closing velocity module (CVM) sends a request for braking to Brake control module (BCM).
At relative speeds up to 15 km/h the collision can be avoided completely, and at speed between 15-30 km/h collision speed can be reduced significantly. City Safety does not work in all driving situations, traffic, weather and road conditions. For example, rain, fog, or snow reduces the system's performance.
For a more detailed description of the system, see Design and Function, Closing velocity module (CVM).
Park Brake Module (PBM)
The park brake module (PBM) regulates the electrically operated parking brake. If the driver activates the parking brake while driving, a request is sent to the brake control module (BCM) to decelerate the vehicle with the help of the brake function. The brake function remains active as long as the button is depressed, but is disabled at speeds below 5 km/h (3.1 mph) as the electrically operated parking brake function then takes over. The driver can activate or deactivate the parking brake by pressing the button or by pressing the accelerator pedal.
For a more detailed description of the system, see Design and Function, Park Brake Module (PBM).