NHTSA Engineering Analysis EA06012

IN A DECEMBER 3, 2007 LETTER, FORD ADVISED NHTSA THAT IT WILL CONDUCT A SAFETY RECALL TO REPLACE THE CAM POSITION SENSOR (CPS) IN APPROXIMATELY 1.2 MILLION SUBJECT VEHICLES TO ADDRESS REPORTS OF ENGINE STALLING.A NEW DESIGN CPS WITH IMPROVED PERFORMANCE AND DURABILITY WILL BE INSTALLED AS A REMEDY.OWNER NOTIFICATIONS WILL BEGIN IN DECEMBER 2007. THE SUBJECT VEHICLES ARE DURABLE, FULL-SIZED, MEDIUM DUTY TRUCKS COMMONLY USED FOR COMMERCIAL PURPOSES, RESCUE/EMERGENCY RESPONSE, AND COMMERCIAL OR RECREATIONAL TOWING.CPS FAILURE IS COMPARABLE TO UNEXPECTEDLY TURNING THE KEY OFF SINCE THE SIGNAL IT PRODUCES IS VITAL TO THE ELECTRONIC ENGINE CONTROL SYSTEM.CPS SIGNAL LOSS TERMINATES FUEL INJECTION RESULTING IN AN ENGINE STALL.ONCE STALLED, THE ENGINE MAY RESTART RIGHT AWAY, OR MAY RESTART AFTER A DELAY (TYPICALLY 5 TO 10 MINUTES), OR MAY NOT RESTART AT ALL.IN ADDITION TO EXPOSING THE DRIVER AND OTHER MOTORISTS TO CRASH RISK DUE TO LOSS OF MOTIVE POWER OR VEHICLE DISABLEMENT, ENGINE STALLING ALSO EFFECTS THE POWER ASSISTED STEERING AND BRAKING. THROUGH CONSUMER INTERVIEWS, ODI DETERMINED THAT CPS FAILURES OCCURRED WITHOUT ANY FORM OF WARNING, AT ANY VEHICLE SPEED (50% AT HIGHWAY SPEEDS), AND UNDER ANY DRIVING CONDITION, SUCH AS ACCELERATING.CONSUMERS REPORTED THAT ABOUT A THIRD OF THE VEHICLES FAILED TO RESTART, WITH ANOTHER THIRD REPORTING DELAYED RESTARTING.HALF THE VEHICLES THAT DID RESTART EXPERIENCED ANOTHER STALL ON THE SAME OR A SUBSEQUENT DRIVE CYCLE (BEFORE CPS REPLACEMENT) RE-EXPOSING THOSE CONSUMERS TO THE RISKS ASSOCIATED WITH A STALLING EVENT.IN THEIR VOQ REPORTS, HALF OF THE ODI COMPLAINANTS DESCRIBED DIFFICULTY CONTROLLING THE VEHICLE DUE TO LOSE OF POWER ASSIST SYSTEMS, ESPECIALLY THOSE WHO WERE TOWING AT THE TIME OF THE INCIDENT. THE ONE ALLEGED INJURY INCIDENT OCCURRED IN AN INTERSECTION WHEN A SUBJECT VEHICLE STALLED WHILE TURNING ACROSS ONCOMING LANES OF TRAFFIC.ALTHOUGH UNSUBSTANTIATED, THE COMPLAINANT ALLEGED AN INJURY TO A CHILD OCCUPANT DURING ODI'S I