1999 Chevrolet Avalanche

The Office of Defects Investigation (ODI) received Defect Petition DP10-003 on March 2, 2010, requesting the investigation of model year (MY) 2003 Chevrolet Silverado 2500HD 4WD pickup trucks for corrosion failures of the vehicle brake lines.DP10-003 was granted and on March 30, 2010, Preliminary Evaluation PE10-010 was opened on more than six million model year 1999 through 2003 light trucks and sport utility vehicles manufactured and sold by General Motors Corporation (GM).On July 2, 2010, ODI received GM's response to an information request, which included GM's assessment of the frequency and safety consequences of the alleged defect. GM stated that:(1) the brake system of the subject vehicles is split front/rear and should a brake pipe suddenly fail for any reason, the affected vehicle would be capable of stopping with the pressure supplied by the remaining circuit; (2) the subject vehicles were designed to meet the hydraulic circuit partial failure requirements of Federal Motor Vehicle Safety Standards 105 and 135, Light Vehicle Brake Systems; and (3) should a brake fluid leak occur for any reason, the brake system malfunction indicator lamp (MIL) would illuminate and warn the driver before the brake fluid level was low enough to cause a loss of line pressure.ODI's and GM's analysis indicates that 85 percent of the complaints occurred on vehicles used primarily in States that use salt on the roads during Winter months (Connecticut, Delaware, District of Columbia, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia and Wisconsin).Overall the complaint rates per 100,000 vehicles for Salt Belt States is 43.0 and Non-Salt Belt is 3.0.In approximately 25 percent of the complaints the brake pipe failure occurred suddenly, with no warning (i.e., no MIL, Brake Fluid Loss Warning), and resulted in extended stopping distances.In 30 of these the increase in stopping distance that resulted was a factor in the crash and in 10 others the vehicle was intentionally steered off the road or into another lane of travel in order to avoid a crash.This investigation has been upgraded to an Engineering Analysis (EA11-001) for subject vehicles sold or currently registered in Salt Belt States to further assess the scope, frequency and safety risks associated with sudden failures of corroded brake pipes that can result in decreased brake effectiveness. ODI will continue to gather information on subject vehicles outside the Salt Belt as well.

THIS INVESTIGATION INVOLVES THE GENERAL MOTORS CORPORATION (GM)THROTTLE BODY (TB) UTILIZED IN MODEL YEAR (MY) 1999-2002 SILVERADO, SIERRA, TAHOE, SUBURBAN, AVALANCHE AND YUKON (SUBJECT VEHICLE(S)) WITH 4.8L, 5.3L, AND 6.0L ENGINES. THE TB VALVE MAY INTERMITTENTLY STICK IN A CLOSED POSITION.IN SUCH A SITUATION, AN OPERATOR MAY APPLY ADDITIONAL ACCELERATOR PEDAL FORCE TO INCREASE ENGINE SPEED.THE APPLICATION OF ADDITIONAL ACCELERATOR PEDAL FORCE, TO OPEN A STUCK THROTTLE VALVE, MAY OPEN THE THROTTLE VALVE MORE THAN INTENDED AND, IN TURN, ACCELERATE THE ENGINE AND VEHICLE MORE THAN INTENDED AND REASONABLY EXPECTED BY THE DRIVER.ON AUGUST 1, 2002, THE OFFICE OF DEFECTS INVESTIGATION (ODI), OF THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION (NHTSA), OPENED THIS ENGINEERING ANALYSIS.THE INVESTIGATION REVEALED THAT TWO FACTORS MAY CAUSE THE DEFECT: 1) TB MANUFACTURING PROCESS PROBLEMS; AND 2) ACCUMULATION OF DEPOSITS (A PCV SYSTEM BY-PRODUCT) ON OR AROUND THE TB THROTTLE VALVE AND BORE.ODI CONCLUDES THAT THE TB PERFORMS IN A DEFECTIVE MANNER AFTER ANALYZING GM?S DATA SUBMISSIONS, AND TEST DATA COLLECTED BY THE VEHICLE RESEARCH AND TEST CENTER (VRTC).FIFTY-NINE CRASHES ARE ALLEGED TO HAVE OCCURRED AS A RESULT OF GM?S TB DEFECT.THE MAJORITY OF THE CRASHES INVOLVE A SINGLE VEHICLE, ENGAGING IN A CLOSE QUARTER VEHICLE MANEUVER (OR LOW SPEED), AND CAUSING ONLY MINOR PROPERTY DAMAGE.FOUR OUT OF THE FIFTY-NINE CRASHES INVOLVE INJURY, AND THOSE INJURIES WERE MINOR.ALTHOUGH GM?S TB IS DEFECTIVE, BASED ON THE EVIDENCE GATHERED, ODI HAS FOUND THAT THE ACCELERATOR PEDAL FORCE REQUIRED TO OPEN A STUCK THROTTLE VALVE IS NEGLIGIBLE, AND THE THROTTLE VALVE DOES NOT STICK IN THE OPEN POSITION.THEREFORE THIS ENGINEERING ANALYSIS (EA02-015) WILL BE CLOSED AT THIS TIME.THE CLOSING OF THIS INVESTIGATION DOES NOT CONSTITUTE A FINDING BY NHTSA THAT A SAFETY-RELATED DEFECT DOES NOT EXIST.FOR A DETAILED DISCUSSION OF THE TB COMPONENT AND TESTING, PLEASE SEE THE ATTACHED REPORT.

DIAGNOSIS OF CRACKED OR BROKEN TRANSMISSION CASE. *TT 2006 AND PRIOR CARS AND LIGHT DUTY TRUCKS. *TT

CONCERNS REGARDING BULLETIN 00-02-35-003F. ALL FULL SIZE TRUCKS AND UTILITIES AND HUMMER PARTS AVAILABLE. *TC

EXHAUST VIBRATION RESONANCE OR MOAN. (2004-2005 GMC DENALI) *SC

SOME CUSTOMERS MAY COMMENT ON A MILD TO SEVERE ENGINE PING (SPARK KNOCK) DURING ACCELERATION AND / OR ILLUMINATED MALFUNCTION INDICATOR LAMP WITH DIAGNOSTIC TROUBLE CODE P0332 SET. *TT

SOME CUSTOMERS MAY COMMENT ON THE SERVICE 4WD INDICATOR ILLUMINATING WITH DIAGNOSTIC TROUBLE CODE B2725 SET. *TT

SUBJECT REGARDING LOSS OF HVAC SYSTEM MODE AND/OR TEMPERATURE CONTROL. *TT