Power steering cuts out or goes heavy

IN PERFORMING THIS ENGINEERING ANALYSIS, ODI DETERMINED THAT THE ELECTRIC POWER STEERING SYSTEM IN THE SUBJECT VEHICLES CAN MALFUNCTION OR FAIL, CAUSING THE DRIVER TO LOSE POWER STEERING ASSISTANCE; HOWEVER, DUE TO THE FOLLOWING REASONS, ODI HAS DECIDED THAT FURTHER EXPENDITURE OF AGENCY RESOURCES ON THIS INVESTIGATION IS NOT WARRANTED AT THIS TIME: - GM ISSUED CUSTOMER SATISFACTION CAMPAIGN (CSC) 04050A INDECEMBER 2004 TO ADDRESS THE ALLEGED DEFECT IN APPROXIMATELY58,700 SUBJECT VEHICLES, ENCOMPASSING AT LEAST 97 PERCENT OF THECOMPLAINT AND WARRANTY CLAIMS POPULATION.VEHICLES OUTSIDE THECSC 04050A POPULATION CONTAIN A NEWLY DESIGNED TORQUE ANDPOSITION SENSOR AND HAVE EXPERIENCED A RELATIVELY LOW COMPLAINTRATE.THIS CUSTOMER SATISFACTION CAMPAIGN PRESENTLY HAS ACOMPLETION RATE OF 52%. - THE IMPACT ON THE DRIVER?S ABILITY TO CONTROL THESE RELATIVELYSMALL AND LIGHT VEHICLES WAS LIMITED.VRTC TEST ENGINEERS WEREUNABLE TO INDUCE A FAILURE MODE THAT WOULD CAUSE THE EPS TOSUBSTANTIALLY LIMIT THE DRIVER?S ABILITY TO TURN THE VEHICLE IN APARTICULAR DIRECTION OR TO PROVIDE THE DRIVER WITH UNINTENDEDPOWER ASSISTANCE.- THERE IS NO RISK OF FIRE.ACCORDINGLY, THIS INVESTIGATION IS CLOSED.THE CLOSING OF THIS INVESTIGATION DOES NOT CONSTITUTE A FINDING BY NHTSA THAT A SAFETY-RELATED DEFECT DOES NOT EXIST.THE AGENCY WILL CONTINUE TO MONITOR COMPLAINTS AND OTHER INFORMATION RELATING TO THE ALLEGED DEFECT IN THE SUBJECT VEHICLES AND TAKE FURTHER ACTION IN THE FUTURE IF WARRANTED BY THE CIRCUMSTAN

ODI OPENED PE04-031 BASED ON EIGHT REPORTS OF ALLEGED POWER STEERING FAILURE IN THE SUBJECT VEHICLES.THE COMPLAINTS ALLEGE THAT THE DRIVER SUDDENLY LOST ALL ELECTRIC POWER STEERING ASSISTANCE WITHOUT WARNING MAKING THE VEHICLE DIFFICULT TO STEER. THE SUBJECT VEHICLE UTILIZES AN ELECTRIC POWER STEERING ASSIST SYSTEM (EPS) THAT PROVIDES VARIABLE STEERING ASSISTANCE BASED ON STEERING WHEEL TORQUE, STEERING WHEEL POSTION, AND VEHICLE SPEED.GENERAL MOTORS DOCUMENTS IDENTIFIED THE FOLLOWING TWO FACTORS THAT CONTRIBUTED TO THE ALLEGED DEFECT IN THE SUBJECT VEHICLES: A.CONTAMINATION OF THE TORQUE AND POSITION SENSOR FROM THESEPARATION OF GREASE APPLIED TO THE STEERING COLUMN ASSEMBLY. B.ELECTRICAL NOISE GENERATED ON THE POWER AND GROUND SLIP RING SURFACES OF THE TORQUE AND POSITION SENSOR.THE NOISE IS GENERATED AS THE SENSOR CONTACT BRUSHES MOVE ALONG THE SLIP RING SURFACES WHEN THE STEERING WHEEL IS ROTATED.ODI'S ANALYSIS SHOWED FAILURERATES THAT ARE OF CONCERN TO ODI AND INDICATED THAT THE ALLEGED DEFECT IS CONTINUING TO OCCUR IN THE SUBJECT VEHICLES. THIS PRELIMINARY EVALUATION HAS BEEN UPGRADED TO AN ENGINEERING ANALYSIS TO FURTHER INVESTIGATE THIS CONCERN, TO ASSESS THE POTENTIAL SAFETY-RELATED CONSEQUENCES, AND TO DETERMINE THE SCOPE OF THE AFFECTED POPULATION.

GM CONDUCTED A SAFETY RECALL (NHTSA # 02V286) TO ADDRESS A STEERING DEFECT PERTAINING TO A LOWER PINION BEARING (LPB) WITHIN THE RACK AND PINION STEERING GEAR (R&P). THE RECALL COVERED 1,159,156 MODEL YEAR 1997-1998 PONTIAC GRAND PRIX VEHICLES BUILT BETWEEN MARCH 1, 1996 AND OCTOBER 31, 1997, 1996-1998 PONTIAC TRANS SPORT, CHEVROLET LUMINA APV, CHEVROLET VENTURE, OLDSMOBILE SILHOUETTE MINIVANS, AND CHEVROLET CAVALIER AND PONTIAC SUNFIRE SEDANS BUILT BETWEEN JANUARY 1, 1996 AND OCTOBER 31, 1997.ODI OPENED THIS RQ AFTER RECEIVING REPORTS THAT OTHER VEHICLES WERE EXHIBITING THE SAME SYMPTOMS AS THE RECALLED VEHICLES.BASED ON ODI'S REVIEW OF TECHNICAL AND COMPLAINT DATA COLLECTED DURING THE RQ, THE W-CARS ARE ASSOCIATED WITH EITHER A HIGHER STEERING COMPLAINT RATE OR A HIGHER LPB FAILURE RATE THAN THE OTHER VEHICLES INVESTIGATED UNDER THE RQ AND ARE ABOVE OR NEAR THE RATES FOR THE RECALLED VEHICLES.THUS, ODI WILL FURTHER EXAMINE THE W-CARS (1996-1997 OLDSMOBILE CUTLASS SUPREME, 1996-1998 BUICK REGAL, CHEVROLET LUMINA, CHEVROLET MONTE CARLO, 1997-1998 BUICK CENTURY, AND 1998 OLDSMOBILE INTRIGUE) UNDER A NEW INVESTIGATION, ENGINEERING ANALYSIS (EA)03-019.

THE LOWER PINION BEARING IN THE RACK AND PINION STEERING ASSEMBLY MAY FAIL.GM WILL RECALL 1997-98 GRAND PRIX BUILT BETWEEN 1-MAR-96 AND 31-OCT-97; AND 1996-98 U-VANS/J-CARS BUILT BETWEEN 1-JAN-96 AND 31-OCT-97.SEE ATTACHED SUMMARY.

ODI HAS RECEIVED 200 COMPLAINTS FROMT CONSUMERS AND 1,238 FROM GM ALLEGING FAILURE OR LOCKUP OF THE STEERING RACK AND PINION UNIT (R&P).THIS ALLEGED CONDITION CAN RESULT IN THE LOSS OF STEERING CONTROL OF THE VEHICLE AND A CRASH CAN RESULT.GM HAS REPORTED SIX CRASHES IN WHICH EIGHT PEOPLE HAVE SUSTAINED INJURIES RANGING FROM BRUISES, AIRBAG BURN, SEAT BELT ABRASION, FACIAL INJURY, NECK AND BACK PAIN.ALL CRASHES WERE SINGLE VEHICLE CRASHES.GM STATES THAT ONE POSSIBLE FAILURE MODE IS FAILURE OF THE LOWER PINION BEARING IN THE R&P.AN ENGINEERING ANALYSIS HAS BEEN OPENED TO DETERMINE IF A SAFETY DEFECT TREND EXISTS.