Brake System Testing

A road test may be required to diagnose brake trouble. The car is to be driven on clean, dry, level and reasonably smooth roads. Do not perform road test on a greasy, wet or dirty road. Testing will also be adversely affected if the roadway is crowned, this will cause the car weight to distribute unevenly to one side.

Test the brakes at different speeds with the use of heavy and light pedal pressure. The Antilock Brake System is designed to engage the Antilock mode anytime that a wheel locking tendency is detected by the EBCM. Application of heavy pedal pressures may cause the ABS to cycle. Indications of this are a rapid pulsation in the brake pedal, accompanied by a popping or ticking noise from the hydraulic unit. During heavy antilock braking on dry pavement, the tires will make intermittent chirping noises as they approach lock-up. This effect is less pronounced on wet or icy pavement, or on dirt or gravel roads.

Before road testing to diagnose ABS-related complaints, see the inspection procedures in Antilock Brake System and Enhanced Traction System.