2005 Chrysler Pacifica Owner's Manual - Page 260

260 STARTING AND OPERATING When the vehicle is driven over 7 mph (11 km/h), you may also hear a slight clicking sound as well as some related motor noises. These noises are the system performing its self check cycle to ensure that the ABS system is working properly. This self check occurs each time the vehicle is started and accelerated past 7 mph (11 km/h). ABS is activated during braking under certain road or stopping conditions. ABS-inducing conditions can include ice, snow, gravel, bumps, railroad tracks, loose debris, or panic stops. You also may experience the following when the brake system goes into Anti-lock: • The ABS motor running (it may continue to run for a short time after the stop), • the clicking sound of solenoid valves, • brake pedal pulsations, • and a slight drop or fall away of the brake pedal at the end of the stop. These are all normal characteristics of ABS. WARNING! The Anti-Lock Brake System contains sophisticated electronic equipment that may be susceptible to interference caused by improperly installed or high output radio transmitting equipment. This interference can cause possible loss of anti-lock braking capability. Installation of such equipment should be performed by qualified professionals. All vehicle wheels and tires must be the same size and type and tires must be properly inflated to produce accurate signals for the computer.