GMC Sierra Service Brakes, Hydraulic Problems

Model years: 1999, 2000, 2001, 2002

Problem: Certain pickup trucks and sport utility vehicles may experience unwanted antilock brake system (abs) activation. This condition is more likely to occur in environmentally corrosive areas. This recall will be launched in the "salt belt" states of connecticut, delaware, illinois, indiana, iowa, maryland, massachusetts, maine, michigan, minnesota, missouri, new hampshire, new jersey, new york, ohio, pennsylvania, rhode island, vermont, west virginia, wisconsin and the district of columbia only.

Risk: This can cause increased stopping distances during low-speed brake applications, which could result in a crash.

Fix: Dealers are to remove the wheel speed sensor and thoroughly clean the wheel speed sensor mounting surface on the bearing, apply rust inhibitor to the cleaned surface, grease the mounting surface, reinstall the wheel speed sensor, and check the peak-to-peak output voltage to ensure the wheel speed signal is within specifications. The recall began september 22, 2005. Owners may contact chevrolet at 1-800-630-2438 or gmc at 1-866-996-9463.

Model years: 2004, 2005

Problem: Certain trucks, sport utility vehicles, and vans equipped with bosch hydro-boost brake assemblies, the hydraulic brake booster pressure accumulator may crack and separate from the hydro-boost assembly during normal operating conditions.

Risk: If a separation occurred and the hood of the vehicle were open, fragments from the accumulator could cause injury to people in the immediate area. The presence of this crack or fractured surface could allow the hydraulic fluid to leak from the accumulator circuit of the booster assembly. The loss of fluid would cause increased steering and braking effort and a crash may occur without prior warning.

Fix: Dealers will test the hydro-boost assembly for functional operation of the two-function valve. If the hydro-boost assembly fails the test, dealers will replace the assembly free of charge. The recall began on march 23, 2005. Owners may contact chevrolet at 1-800-630-2438, gmc trucks at 1-866-996-9463 and hummer at 1-800-732-5493.

Model years: 2003, 2004

Problem: Certain sport utility vehicles, pickup trucks, and passenger vans fail to comply with the requirements of federal motor vehicle safety standard no. 135, ?passenger car brake systems.? Some of these vehicles were produced with an out-of-specification brake hydro-boost housing relief valve bore.

Risk: Consequently, the valve o-ring seal may fracture. Steering efforts may be slightly increased while braking or parking. Under certain driving conditions, a fractured seal may require a slight increase in the applied brake pedal effort to achieve the same vehicle deceleration rate as prior to the seat fracture.

Fix: Dealers are to replace the hydro-boost relief valve. The recall began on june 18, 2004. Owners should contact cadillac at 1-866-982-2339; chevrolet at 1-800-630-2438; gmc at 1-866-996-9463; or hummer at 1-866-486-6376.

Model years: 1999, 2000

Problem: Vehicle description: light duty pickup trucks and sport utility vehicles. Some of these vehicles have a clearance condition between the front right-hand brake pipe and the body cross sill that could decrease to the point of allowing contact during the life of the vehicle. If contact occurs and the brake pipe becomes damaged, in half of the brake system there can be a loss of brake fluid and pressure. The brake warning lamp will be activated when the brake fluid level reaches the indicator limit.

Risk: During braking, the pedal will be lower than normal and stopping distances will be longer. If this occurs when stopping distance is limited, a crash could occur.

Fix: Dealers will inspect the front right-hand brake pipe for wear. If there are signs of wear, this section of the brake pipe will be replaced with a new designed brake pipe section. If there are not signs of wear on the brake pipe, the dealer will install a spacer clip to ensure sufficient clearance between the brake pipe and the body cross sill.

Model years: 2000

Problem: Vehicle description: light duty pickup trucks equipped with 4-wheel disc brakes. Some of these vehicles have an antilock brake system (abs) motor containing an out-of-specification spring clip. This clip could allow the motor bearing to become misaligned. If misalignment occurs, eventually the abs would be non-functional.

Risk: The base brakes would remain fully functional, but the dynamic rear proportioning (drp) system, which optimizes front to rear brake balance, would become inoperative.

Fix: Dealers will replace the brake pressure module valve assembly.