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Cayenne

2015-2016 Cayenne – Manual

2015-2016 Cayenne – Manual

Page: 200

Function
Sensors continuously measure:

  1. Speed
  2. Direction of travel (steering angle)
  3. Lateral acceleration
  4. Axial acceleration
  5. Rate of turn about the vertical axis

PSM uses these values to determine the direction of travel desired by the driver.

PSM intervenes and corrects the course if the actual direction of motion of the vehicle deviates from the desired course (steering-wheel position):
It brakes individual wheels as needed. In addition, engine power is reduced in order to stabilise the vehicle, if necessary. The following indications inform the driver of PSM control operations and warn him to adapt his driving style to the road conditions:

  1. PSM warning light on the instrument panel flashes.
  2. Hydraulic noises can be heard.
  3. The vehicle decelerates and steering-wheel forces are altered as PSM controls the brakes.
  4. Reduced engine power.
  5. The brake pedal pulsates and its position is changed during braking.
    In order to achieve full vehicle deceleration, foot pressure must be increased after the brake pedal has begun to pulsate.

Examples of PSM control operations

  1. If the “front wheels of the vehicle drift” on a bend, the engine power is reduced and the rear wheel on the inside of the bend is braked if necessary.
  2. If the rear of the vehicle swings out on a bend, the front wheel on the outside of the bend is braked.
  3. Brake system prefilling:
    The brake system is prepared for possible subsequent emergency braking if the accelerator pedal is released suddenly and quickly. The brake system is prefilled and the brake pads are already applied gently to the brake discs.
  4. Brake booster (Hydraulic Brake Assist):
    In the event of an emergency braking operation where the pedal force is insufficient, a brake booster provides the braking pressure necessary for maximum deceleration at all 4 wheels.

Combined operation of PSM and PTV Plus
In order to ensure optimum stabilisation of the vehicle, the rear-differential lock is influenced when PSM interventions occur on vehicles with PTV Plus.

Combined operation of PSM and PTM
In order to ensure optimum stabilisation of the vehicle, torque distribution between the front and rear wheels is also adapted when PSM interventions occur.

If PSM was switched off manually, it is switched on again automatically in the event of a PTM fault.

PSM can be switched off again by pressing button again.

Off-road PSM (PSM in the off-road driving programme)
When off-road mode is active, an off-road PSM specially matched to off-road driving is activated automatically to improve traction.

In order to improve driveability on difficult terrain, the response of the off-road PSM is less sensitive in the low speed range when the vehicle is set to the off-road driving programme.

Automatic brake differential (ABD)
The ABD system controls the front and rear axles separately. If one wheel of an axle starts to spin, it is braked so that the other wheel on the same axle can be driven.

ABD recognises different driving states, and it features control strategies adapted to these states. In situations in which little propulsive power is required, such as when the vehicle moves off on a level gravel surface, traction control already becomes active at low engine speeds. If a large amount of propulsive power is required, such as when moving off on an uphill slope or for rapid acceleration, the ABD system is adapted accordingly.

Anti-slip regulation (ASR)
The anti-slip regulation system prevents the wheels from spinning by adjusting the engine power, thereby ensuring good lane-holding ability and stable handling.

Engine drag torque control (MSR)
In conditions of excessive slip, the engine drag torque control system prevents all driven wheels from locking up when the vehicle is overrunning. This is also the case for downshifts on a slippery road.

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