NHTSA Preliminary Evaluation PE03029

SUBARU'S SUPPLEMENTAL RESPONSE OF SEPTEMBER 29, 2003, IDENTIFIED THAT THE 2002, 2003 SUBARU WRX MODELS AREEQUIPPED WITH THE BOSCH 5.3 ABS SYSTEM, AND IDENTIFIED THAT OTHER MODEL SUBARU VEHICLES ARE ALSO EQUIPPED WITH THE BOSCH 5.3 ABS SYSTEM, BUT HAVE DIFFERENT CALIBRATIONS THAN THE WRX MODEL VEHICLES.SUBARU IDENTIFIED THAT CHANGES WERE MADE IN THE ABS ECU TO ADDRESS A CALIBRATION LOGIC ISSUE WHEN DRIVING THE VEHICLE WITH THE SPARE TIRE MOUNTED.SUBARU REPORTED THAT BOTH THE ABS HYDRAULIC UNIT AND THE ABS ECU WERE MODIFIED, AND GAVE VIN NUMBERS TO IDENTIFY THE IMPLEMENTATION OF THE MODIFIED UNITS IN PRODUCTION. TESTING IS UNDERWAY TO GAIN AN UNDERSTANDING OF THE WRX VEHICLE PERFORMANCE DURING AN ABS ACTIVATION.FUTHER, ANALYSIS OFTHE DIFFERENCES IN VEHICLE PERFORMANCE RESULTING FROM ABS SOFTWARE CHANGES WILL BE EXAMINED.