2000 Saab 9-5 Owner's Manual - Page 147

Starting and driving How the system works 147 Traction Control System The traction control system (TCS) is designed to prevent wheelspin. This enables the car to achieve the best possible grip and, hence, maximum tractive effort, together with greater stability. The TCS system uses information from the ABS system's wheel sensors to detect when the front (driving) wheels are rotating faster then the rear wheels. It then monitors whether one driving wheel is rotating faster than the other. If so, the faster wheel is retarded until both wheels are rotating at the same speed. If the two front wheels are rotating at the same speed but are turning faster than the rear wheels, the torque from the engine is reduced to eliminate the difference. The process continues until all the wheels are rotating at the same speed. The advantages of the TCS system become most apparent when the cohesion between the front wheels and the road surface is so low that one or both of the wheels would lose their grip were the car not equipped with the TCS, e.g.: • When the car is pulling away or accelerating with the front wheels on different surfaces (e.g. one slippery and one dry). The TCS then functions like an electronic differential lock. • When the car is pulling away or accelerating on a slippery road, in which case the IB476 Braking with ABS brakes When the system is operating, the brake pedal will pulsate gently and the system will make a ticking noise Braking with ABS - evasive steering Do not release the brake pedal before the car has come to a halt or the danger is past! That is critical. If the road is slippery, the ABS system will operate even when only light pressure is applied to the pedal. This means that you can brake gently to test the condition of the road and adapt your driving accordingly. It is well worth practicing the use of ABS brakes on a skid pan or other suitable facility. The ABS system will not reduce the braking distance on loose gravel or on snow or ice but, because the wheels cannot lock up, some steering control is retained. When the ABS system is working, i.e. modulation of the brake pressure is in progress, the brake pedal will pulsate and a ticking noise will be heard. All this is perfectly normal. Press the pedal down hard (you cannot press too hard) and steer the car to safety. IB477