2006 Jeep Grand Cherokee Owner's Manual - Page 270
2006 Jeep Grand Cherokee Manual
Page 270 highlights
270 STARTING AND OPERATING WARNING! Significant over or under inflation of tires, or mixing sizes of tires or wheels on the vehicle can lead to loss of braking effectiveness. The Anti-Lock Brake System conducts a low-speed selftest at about 12 mph (20 km/h). If you have your foot lightly on the brake while this test is occurring you may feel slight pedal movement. The movement can be more apparent on ice and snow. This is normal. The Anti-Lock Brake System pump motor runs during the self-test at 12 mph (20 km/h) and during an ABS stop. The pump motor makes a low humming noise during operation, which is normal. WARNING! Pumping of the Anti-Lock Brakes will diminish their effectiveness and may lead to an accident. Pumping makes the stopping distance longer. Just press firmly on your brake pedal when you need to slow down or stop.