IllustrationLEAVING MY JOB TODAY , WAS BACKING OUT AND WENT TO STOP AND RIGHT REAR BRAKE LINE BLEW LEG GOT BEAT UP TRYING TO JAM ON PARKING BRAKE AND TWISTED LEFT LEG IN PANIC BRAKE LINE BLEW NEXT TO FUEL TANK. *TR
2000 Chevrolet C/K Series
Owner reports · Recalls · Investigations
Limited comparison data
There is not enough comparable history to draw a useful model-year comparison.
About this comparison →How this year compares
Owner complaints by model year
Compare all C/k Series years →Counts vary with age, sales and reporting. They are not failure rates.
What owners reported most
Tap a category to read its complaints. One report may name several components.
When problems were reported
Mileage at the reported incident
Limited mileage data: 2 of 2 reports include usable mileage. There isn’t enough coverage to show a useful chart.
NHTSA’s mileage field refers to the reported incident, not necessarily the filing date. This shows report counts, not the likelihood of a failure.
What to inspect
Issues worth paying extra attention to based on owner reports.
- Service Brakes. Review the 1 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
- Service Brakes, Air. Review the 1 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
NHTSA owner reports · September 18, 2026 snapshot.
0 crash reports0 fire reports1 injury reports
What owners actually said
2 reportsI HAVE OWNED A 2000 CHEVY TAHOE FOR 3+ YEAR AND HAVE HAD ANTI LOCK BRAKE PROBLEMS. THE BRAKE DO NOT ENGAGE SOMETIMES AND ALMOST CAUSE ME TO CRASH AND CREATING A DAMGEROUS SITUATION. I AM A CAREFUL DRIVER SO I ALWAY KEEP THE PROBLEM IN MIND AND TRY TO ALWAYS GIVE MY SELF ENOUGH TIME TO STOP, BUT SOMETIME IN EMERGENCY WHEN I RE…
Read full complaint
I HAVE OWNED A 2000 CHEVY TAHOE FOR 3+ YEAR AND HAVE HAD ANTI LOCK BRAKE PROBLEMS. THE BRAKE DO NOT ENGAGE SOMETIMES AND ALMOST CAUSE ME TO CRASH AND CREATING A DAMGEROUS SITUATION. I AM A CAREFUL DRIVER SO I ALWAY KEEP THE PROBLEM IN MIND AND TRY TO ALWAYS GIVE MY SELF ENOUGH TIME TO STOP, BUT SOMETIME IN EMERGENCY WHEN I REALLY NEED THE BRAKES THEY DON'T ENGAGE AND HAVE ALMOST HAD ACCIDENTS. THIS HAS BEEN AN ON GOING PROBLEM EVER SINCE I BOUGHT THE CAR. THE BRAKE DON'T ENGAGE AND THE VEHICLE KEEPS GOING EVEN WITH FULL PRESSURE. MOST OBVIOUS WHEN ROAD IS WET. VERY SCARY
Official recalls
0No recalls in this snapshot.
Model-level recall history does not show whether a particular VIN is affected or has received a repair. Check a VIN with NHTSA ↗
NHTSA investigations
5DP05009 · Parking Brake Failure
Opened Dec 20, 2005 · Closed May 31, 2006
Status: closed (inferred from source dates) · Parking Brake; Parking Brake:conventional; Parking Brake:conventional:mechanical
ODI'S REVIEW OF COMPLAINT DATA RECEIVED SINCE THE CLOSE OF EA04-011 REVEALED NO INDICATION THAT THE INVESTIGATION SHOULD BE RE-OPENED.MORE DETAILS CAN BE FOUND IN THE FEDERAL REGISTER NOTICE ENCLOSED IN THE DP05-009 PUBLIC FILE.ODI RESERVES THE RIGHT TO REOPEN THE INVESTIGATION IN THE FUTURE SHOULD CONDITIONS WARRANT.
Additional source detail variants (3)
Parking Brake:conventional
ODI'S REVIEW OF COMPLAINT DATA RECEIVED SINCE THE CLOSE OF EA04-011 REVEALED NO INDICATION THAT THE INVESTIGATION SHOULD BE RE-OPENED.MORE DETAILS CAN BE FOUND IN THE FEDERAL REGISTER NOTICE ENCLOSED IN THE DP05-009 PUBLIC FILE.ODI RESERVES THE RIGHT TO REOPEN THE INVESTIGATION IN THE FUTURE SHOULD CONDITIONS WARRANT.
Parking Brake:conventional:mechanical
ODI'S REVIEW OF COMPLAINT DATA RECEIVED SINCE THE CLOSE OF EA04-011 REVEALED NO INDICATION THAT THE INVESTIGATION SHOULD BE RE-OPENED.MORE DETAILS CAN BE FOUND IN THE FEDERAL REGISTER NOTICE ENCLOSED IN THE DP05-009 PUBLIC FILE.ODI RESERVES THE RIGHT TO REOPEN THE INVESTIGATION IN THE FUTURE SHOULD CONDITIONS WARRANT.
Parking Brake
ODI'S REVIEW OF COMPLAINT DATA RECEIVED SINCE THE CLOSE OF EA04-011 REVEALED NO INDICATION THAT THE INVESTIGATION SHOULD BE RE-OPENED.MORE DETAILS CAN BE FOUND IN THE FEDERAL REGISTER NOTICE ENCLOSED IN THE DP05-009 PUBLIC FILE.ODI RESERVES THE RIGHT TO REOPEN THE INVESTIGATION IN THE FUTURE SHOULD CONDITIONS WARRANT.
EA04012 · Hydraulic Pump Failres
Opened Apr 30, 2004 · Closed Feb 28, 2005
Status: closed (inferred from source dates) · Service Brakes, Hydraulic:power Assist; Steering:hydraulic Power Assist System
GM IS CONDUCTING A RECALL ON ALL SUBJECT VEHICLES BUILD BETWEEN MAY 1999 AND OCTOBER 14, 1999.SIGNIFICANT CHANGES WERE INCORPORATED INTO PRODUCTION IN EARLY OCTOBER 1999, AND VEHICLES BUILT AFTER THAT DATE HAVE LOWER WARRANTY FAILURE RATES.THE COMPLAINT AND WARRANTY DATA APPEAR TO SUPPORT THE EFFECTIVENESS OF THESE CHANGES. GM MADE ADDITIONAL CHANGES IN NOVEMBER 1999, FEBRUARY 2000, MAY 2001, AND FEBRUARY 2004.ODI WILL CONTINUE TO MONITOR THIS PROBLEM AND WILL TAKE FURTHER ACTION, IF WARRANTED, IN THE FUTURE.FOR FURTHER TECHNICAL DETAILS SEE THE ATTACHED ENGINEERING ANALYSIS REPORT.
Additional source detail variants (2)
Service Brakes, Hydraulic:power Assist
GM IS CONDUCTING A RECALL ON ALL SUBJECT VEHICLES BUILD BETWEEN MAY 1999 AND OCTOBER 14, 1999.SIGNIFICANT CHANGES WERE INCORPORATED INTO PRODUCTION IN EARLY OCTOBER 1999, AND VEHICLES BUILT AFTER THAT DATE HAVE LOWER WARRANTY FAILURE RATES.THE COMPLAINT AND WARRANTY DATA APPEAR TO SUPPORT THE EFFECTIVENESS OF THESE CHANGES. GM MADE ADDITIONAL CHANGES IN NOVEMBER 1999, FEBRUARY 2000, MAY 2001, AND FEBRUARY 2004.ODI WILL CONTINUE TO MONITOR THIS PROBLEM AND WILL TAKE FURTHER ACTION, IF WARRANTED, IN THE FUTURE.FOR FURTHER TECHNICAL DETAILS SEE THE ATTACHED ENGINEERING ANALYSIS REPORT.
Steering:hydraulic Power Assist System
GM IS CONDUCTING A RECALL ON ALL SUBJECT VEHICLES BUILD BETWEEN MAY 1999 AND OCTOBER 14, 1999.SIGNIFICANT CHANGES WERE INCORPORATED INTO PRODUCTION IN EARLY OCTOBER 1999, AND VEHICLES BUILT AFTER THAT DATE HAVE LOWER WARRANTY FAILURE RATES.THE COMPLAINT AND WARRANTY DATA APPEAR TO SUPPORT THE EFFECTIVENESS OF THESE CHANGES. GM MADE ADDITIONAL CHANGES IN NOVEMBER 1999, FEBRUARY 2000, MAY 2001, AND FEBRUARY 2004.ODI WILL CONTINUE TO MONITOR THIS PROBLEM AND WILL TAKE FURTHER ACTION, IF WARRANTED, IN THE FUTURE.FOR FURTHER TECHNICAL DETAILS SEE THE ATTACHED ENGINEERING ANALYSIS REPORT.
EA04011 · Parking Brake Failure
Opened Apr 9, 2004 · Closed May 10, 2005
Status: closed (inferred from source dates) · Parking Brake; Parking Brake:conventional; Parking Brake:conventional:mechanical; Parking Brake:conventional:mechanical:linkage And Cable
IN A LETTER DATED APRIL 20, 2005, GM NOTIFIED NHTSA THAT IT HAD DECIDED THAT DEFECTS THAT RELATE TO MOTOR VEHICLE SAFETY EXIST IN CERTAIN MODEL YEAR (MY) 1999-2002 C/K 1500 SERIES (PBR PARKING BRAKE SYSTEM) AND MY 2001-2005 C/K 2500 AND 3500 SERIES (TRW PARKING BRAKE SYSTEM) PICKUPS WITH MANUAL TRANSMISSIONS.ACCORDING TO GM, SOME OF THESE VEHICLES MAY HAVE CONDITIONS THAT CAUSE THE FRICTION LININGS TO WEAR TO AN EXTENT WHERE THE PARKING BRAKE CAN BECOME INEFFECTIVE IN IMMOBILIZING A PARKED VEHICLE.GM'S ACTION COVERS AN ESTIMATED TOTAL OF 142,585 VEHICLES.DEALERS WILL INSTALL A LOW-FORCE SPRING CLIP RETAINER FOR VEHICLES EQUIPPED WITH THE PBR PARKING BRAKE SYSTEM AND INSTALL A REDESIGNED PARKING BRAKE CABLE ASSEMBLY ON VEHICLES EQUIPPED WITH THE TRW PARKING BRAKE SYSTEM. A TOTAL OF 58 NON-DUPLICATIVE COMPLAINTS WERE RECEIVED BY ODI AND GM CONCERNING THE APPROXIMATELY 59,000 MY 1999-2002 C/K 1500 SERIES PICKUP TRUCKS WITH THE PBR PARKING BRAKE SYSTEM.THESE INCLUDED 22 ALLEGED ROLLAWAY INCIDENTS, RESULTING IN A RATE OF 38.5 ROLLAWAY INCIDENTS PER 100,000 VEHICLES.ODI IS AWARE OF 24 COMPLAINTS REGARDING THE MY 2001-2005 C/K 2500 AND 3500 SERIES MANUAL TRANSMISSION TRUCKS RECALLED BY GM, INCLUDING 5 ALLEGING ROLLAWAY INCIDENTS.THOUGH THE CONDITIONS DESCRIBED IN GM'S LETTER ARE ALSO PRESENT IN THE C/K TRUCKS WITH AUTOMATIC TRANSMISSIONS, THE ROLLAWAY RATE IN THOSE VEHICLES WAS SIMILAR TO THOSE OBSERVED IN PEER VEHICLES STUDIED BY ODI IN THIS INVESTIGATION.THIS ENGINEERING ANALYSIS IS CLOSED. FOR ADDITIONAL INFORMATION, SEE THE ATTACHED CLOSING REPORT.
Additional source detail variants (4)
Parking Brake:conventional
IN A LETTER DATED APRIL 20, 2005, GM NOTIFIED NHTSA THAT IT HAD DECIDED THAT DEFECTS THAT RELATE TO MOTOR VEHICLE SAFETY EXIST IN CERTAIN MODEL YEAR (MY) 1999-2002 C/K 1500 SERIES (PBR PARKING BRAKE SYSTEM) AND MY 2001-2005 C/K 2500 AND 3500 SERIES (TRW PARKING BRAKE SYSTEM) PICKUPS WITH MANUAL TRANSMISSIONS.ACCORDING TO GM, SOME OF THESE VEHICLES MAY HAVE CONDITIONS THAT CAUSE THE FRICTION LININGS TO WEAR TO AN EXTENT WHERE THE PARKING BRAKE CAN BECOME INEFFECTIVE IN IMMOBILIZING A PARKED VEHICLE.GM'S ACTION COVERS AN ESTIMATED TOTAL OF 142,585 VEHICLES.DEALERS WILL INSTALL A LOW-FORCE SPRING CLIP RETAINER FOR VEHICLES EQUIPPED WITH THE PBR PARKING BRAKE SYSTEM AND INSTALL A REDESIGNED PARKING BRAKE CABLE ASSEMBLY ON VEHICLES EQUIPPED WITH THE TRW PARKING BRAKE SYSTEM. A TOTAL OF 58 NON-DUPLICATIVE COMPLAINTS WERE RECEIVED BY ODI AND GM CONCERNING THE APPROXIMATELY 59,000 MY 1999-2002 C/K 1500 SERIES PICKUP TRUCKS WITH THE PBR PARKING BRAKE SYSTEM.THESE INCLUDED 22 ALLEGED ROLLAWAY INCIDENTS, RESULTING IN A RATE OF 38.5 ROLLAWAY INCIDENTS PER 100,000 VEHICLES.ODI IS AWARE OF 24 COMPLAINTS REGARDING THE MY 2001-2005 C/K 2500 AND 3500 SERIES MANUAL TRANSMISSION TRUCKS RECALLED BY GM, INCLUDING 5 ALLEGING ROLLAWAY INCIDENTS.THOUGH THE CONDITIONS DESCRIBED IN GM'S LETTER ARE ALSO PRESENT IN THE C/K TRUCKS WITH AUTOMATIC TRANSMISSIONS, THE ROLLAWAY RATE IN THOSE VEHICLES WAS SIMILAR TO THOSE OBSERVED IN PEER VEHICLES STUDIED BY ODI IN THIS INVESTIGATION.THIS ENGINEERING ANALYSIS IS CLOSED. FOR ADDITIONAL INFORMATION, SEE THE ATTACHED CLOSING REPORT.
Parking Brake:conventional:mechanical
IN A LETTER DATED APRIL 20, 2005, GM NOTIFIED NHTSA THAT IT HAD DECIDED THAT DEFECTS THAT RELATE TO MOTOR VEHICLE SAFETY EXIST IN CERTAIN MODEL YEAR (MY) 1999-2002 C/K 1500 SERIES (PBR PARKING BRAKE SYSTEM) AND MY 2001-2005 C/K 2500 AND 3500 SERIES (TRW PARKING BRAKE SYSTEM) PICKUPS WITH MANUAL TRANSMISSIONS.ACCORDING TO GM, SOME OF THESE VEHICLES MAY HAVE CONDITIONS THAT CAUSE THE FRICTION LININGS TO WEAR TO AN EXTENT WHERE THE PARKING BRAKE CAN BECOME INEFFECTIVE IN IMMOBILIZING A PARKED VEHICLE.GM'S ACTION COVERS AN ESTIMATED TOTAL OF 142,585 VEHICLES.DEALERS WILL INSTALL A LOW-FORCE SPRING CLIP RETAINER FOR VEHICLES EQUIPPED WITH THE PBR PARKING BRAKE SYSTEM AND INSTALL A REDESIGNED PARKING BRAKE CABLE ASSEMBLY ON VEHICLES EQUIPPED WITH THE TRW PARKING BRAKE SYSTEM. A TOTAL OF 58 NON-DUPLICATIVE COMPLAINTS WERE RECEIVED BY ODI AND GM CONCERNING THE APPROXIMATELY 59,000 MY 1999-2002 C/K 1500 SERIES PICKUP TRUCKS WITH THE PBR PARKING BRAKE SYSTEM.THESE INCLUDED 22 ALLEGED ROLLAWAY INCIDENTS, RESULTING IN A RATE OF 38.5 ROLLAWAY INCIDENTS PER 100,000 VEHICLES.ODI IS AWARE OF 24 COMPLAINTS REGARDING THE MY 2001-2005 C/K 2500 AND 3500 SERIES MANUAL TRANSMISSION TRUCKS RECALLED BY GM, INCLUDING 5 ALLEGING ROLLAWAY INCIDENTS.THOUGH THE CONDITIONS DESCRIBED IN GM'S LETTER ARE ALSO PRESENT IN THE C/K TRUCKS WITH AUTOMATIC TRANSMISSIONS, THE ROLLAWAY RATE IN THOSE VEHICLES WAS SIMILAR TO THOSE OBSERVED IN PEER VEHICLES STUDIED BY ODI IN THIS INVESTIGATION.THIS ENGINEERING ANALYSIS IS CLOSED. FOR ADDITIONAL INFORMATION, SEE THE ATTACHED CLOSING REPORT.
Parking Brake:conventional:mechanical:linkage And Cable
IN A LETTER DATED APRIL 20, 2005, GM NOTIFIED NHTSA THAT IT HAD DECIDED THAT DEFECTS THAT RELATE TO MOTOR VEHICLE SAFETY EXIST IN CERTAIN MODEL YEAR (MY) 1999-2002 C/K 1500 SERIES (PBR PARKING BRAKE SYSTEM) AND MY 2001-2005 C/K 2500 AND 3500 SERIES (TRW PARKING BRAKE SYSTEM) PICKUPS WITH MANUAL TRANSMISSIONS.ACCORDING TO GM, SOME OF THESE VEHICLES MAY HAVE CONDITIONS THAT CAUSE THE FRICTION LININGS TO WEAR TO AN EXTENT WHERE THE PARKING BRAKE CAN BECOME INEFFECTIVE IN IMMOBILIZING A PARKED VEHICLE.GM'S ACTION COVERS AN ESTIMATED TOTAL OF 142,585 VEHICLES.DEALERS WILL INSTALL A LOW-FORCE SPRING CLIP RETAINER FOR VEHICLES EQUIPPED WITH THE PBR PARKING BRAKE SYSTEM AND INSTALL A REDESIGNED PARKING BRAKE CABLE ASSEMBLY ON VEHICLES EQUIPPED WITH THE TRW PARKING BRAKE SYSTEM. A TOTAL OF 58 NON-DUPLICATIVE COMPLAINTS WERE RECEIVED BY ODI AND GM CONCERNING THE APPROXIMATELY 59,000 MY 1999-2002 C/K 1500 SERIES PICKUP TRUCKS WITH THE PBR PARKING BRAKE SYSTEM.THESE INCLUDED 22 ALLEGED ROLLAWAY INCIDENTS, RESULTING IN A RATE OF 38.5 ROLLAWAY INCIDENTS PER 100,000 VEHICLES.ODI IS AWARE OF 24 COMPLAINTS REGARDING THE MY 2001-2005 C/K 2500 AND 3500 SERIES MANUAL TRANSMISSION TRUCKS RECALLED BY GM, INCLUDING 5 ALLEGING ROLLAWAY INCIDENTS.THOUGH THE CONDITIONS DESCRIBED IN GM'S LETTER ARE ALSO PRESENT IN THE C/K TRUCKS WITH AUTOMATIC TRANSMISSIONS, THE ROLLAWAY RATE IN THOSE VEHICLES WAS SIMILAR TO THOSE OBSERVED IN PEER VEHICLES STUDIED BY ODI IN THIS INVESTIGATION.THIS ENGINEERING ANALYSIS IS CLOSED. FOR ADDITIONAL INFORMATION, SEE THE ATTACHED CLOSING REPORT.
Parking Brake
IN A LETTER DATED APRIL 20, 2005, GM NOTIFIED NHTSA THAT IT HAD DECIDED THAT DEFECTS THAT RELATE TO MOTOR VEHICLE SAFETY EXIST IN CERTAIN MODEL YEAR (MY) 1999-2002 C/K 1500 SERIES (PBR PARKING BRAKE SYSTEM) AND MY 2001-2005 C/K 2500 AND 3500 SERIES (TRW PARKING BRAKE SYSTEM) PICKUPS WITH MANUAL TRANSMISSIONS.ACCORDING TO GM, SOME OF THESE VEHICLES MAY HAVE CONDITIONS THAT CAUSE THE FRICTION LININGS TO WEAR TO AN EXTENT WHERE THE PARKING BRAKE CAN BECOME INEFFECTIVE IN IMMOBILIZING A PARKED VEHICLE.GM'S ACTION COVERS AN ESTIMATED TOTAL OF 142,585 VEHICLES.DEALERS WILL INSTALL A LOW-FORCE SPRING CLIP RETAINER FOR VEHICLES EQUIPPED WITH THE PBR PARKING BRAKE SYSTEM AND INSTALL A REDESIGNED PARKING BRAKE CABLE ASSEMBLY ON VEHICLES EQUIPPED WITH THE TRW PARKING BRAKE SYSTEM. A TOTAL OF 58 NON-DUPLICATIVE COMPLAINTS WERE RECEIVED BY ODI AND GM CONCERNING THE APPROXIMATELY 59,000 MY 1999-2002 C/K 1500 SERIES PICKUP TRUCKS WITH THE PBR PARKING BRAKE SYSTEM.THESE INCLUDED 22 ALLEGED ROLLAWAY INCIDENTS, RESULTING IN A RATE OF 38.5 ROLLAWAY INCIDENTS PER 100,000 VEHICLES.ODI IS AWARE OF 24 COMPLAINTS REGARDING THE MY 2001-2005 C/K 2500 AND 3500 SERIES MANUAL TRANSMISSION TRUCKS RECALLED BY GM, INCLUDING 5 ALLEGING ROLLAWAY INCIDENTS.THOUGH THE CONDITIONS DESCRIBED IN GM'S LETTER ARE ALSO PRESENT IN THE C/K TRUCKS WITH AUTOMATIC TRANSMISSIONS, THE ROLLAWAY RATE IN THOSE VEHICLES WAS SIMILAR TO THOSE OBSERVED IN PEER VEHICLES STUDIED BY ODI IN THIS INVESTIGATION.THIS ENGINEERING ANALYSIS IS CLOSED. FOR ADDITIONAL INFORMATION, SEE THE ATTACHED CLOSING REPORT.
PE03057 · Parking Brake Failure
Opened Dec 8, 2003 · Closed Apr 9, 2004
Status: closed (inferred from source dates) · Parking Brake
ODI OPENED PE03-057 TO ASSESS PARKING BRAKE INEFFECTIVENESS IN THE SUBJECT VEHICLES.THESE VEHICLES ARE EQUIPPED WITH FOUR WHEEL DISC BRAKES THAT INCORPORATE A SINGLE-SHOE DRUM-IN-HAT PARKING BRAKE INDEPENDENT OF THE SERVICE BRAKES.COMPLAINT AND WARRANTY DATA INDICATE THAT THE PARKING BRAKE LININGS TEND TO WEAR OUT EARLY IN THE LIFE OF THE VEHICLE (AT AN AVERAGE OF 24 MONTHS IN SERVICE), REDUCING THE PARKING BRAKE SYSTEM'S TORQUE BELOW THAT NEEDED TO IMMOBILIZE THE VEHICLE.GM HAS ATTRIBUTED THIS ACCELERATED WEAR TO FOREIGN MATERIAL INTRUSION AND A FAILURE OF THE BRAKE SHOE TO PROPERLY SELF-CENTER WITHIN ITS BRAKE DRUM.EFFECTIVE WITH THE START OF MY 2003 PRODUCTION, A NEWER REDUCED FORCE HOLD-DOWN CLIP WAS INTRODUCED TO FACILITATE BRAKE SHOE DISENGAGEMENT FROM THE DRUM SURFACE.THIS PART IS ALSO AVAILABLE AT THE SERVICE LEVEL FOR THE MY 1999-2002 VEHICLES.GM HAS INDICATED THAT THE PAKING BRAKE IS INTENDED TO OPERATE IN CONJUNCTION WITH THE TRANSMISSION TO IMMOBILZE PARKED VEHICLES, AND THAT IN MANY CASES, ACCELERATED PARKING BRAKE LINING WEAR IS CAUSED BY ROUGH USE, VEHICLE MODIFICATIONS, AND DRIVING WITH THE PARKING ENGAGED. ODI HAS UPGRADED THE PRELIMINARY EVALUATION TO AN ENGINEERING ANALYSIS TO GATHER FURTHER INFORMATION CONCERNING PARKING BRAKE USAGE FACTORS AND THE CIRCUMSTANCES SURROUNDING THE SEVENTEEN REPORTED VEHICLE CRASHES.
EA01013 · Vacuum Brake Booster Failure
Opened May 22, 2001 · Closed Dec 15, 2002
Status: closed (inferred from source dates) · Service Brakes, Hydraulic
ODI UPGRADED THE PRELIMINARY EVALUATION TO CONDUCT A FULL TECHNICAL ANALYSIS, INCLUDING TESTING.THE TESTING AND ANALYSIS SHOWS THAT A TORN DIAPHRAGM IS A SLOW PROGRESSIVE TYPE OF FAILURE.THE TEAR PROPAGATES IN A SLOW METHODICAL MANNER AND BRAKING PERFORMANCE IS SIMILAR TO AN UNTORN UNIT UNTIL THE TEAR EXCEEDS 1/2 INCH.ODI'S TESTING INDICATES THAT TEARS GREATER THAN 1/2 INCH REQUIRED INCREASED PEDAL EFFORT.HOWEVER, AS THE LENGTH OF THE TEAR INCREASED BEYOND 1/2 INCH, A HISSING SOUND COULD BE HEARD EMITTING INTO THE PASSENGER COMPARTMENT WHERE THE MASTER CYLINDER PLUNGER PASSED THROUGH THE FIREWALL. ODI HAS DETERMINED THAT A SAFETY-RELATED DEFECT TREND HAS NOT BEEN IDENTIFIED AT THIS TIME AND FURTHER USE OF AGENCY RESOURCES DOES NOT APPEAR TO BE WARRANTED.THE CLOSING OF THIS INVESTIGATION DOES NOT CONSTITUTE A FINDING THAT NO SAFETY-RELATED DEFECT EXISTS.THE AGENCY RESERVES THE RIGHT TO TAKE FURTHER ACTION IN THE FUTURE IF WARRANTED BY THE CIRCUMSTANCES.ODI'S COMPLETE TECHNICAL ANALYSIS WITH TEST DATA IS ATTACHED.