Description of the problem | On feb 13, i was driving an ann arbor, mi, street that was downhill and icy. I pressed the brake pedal until the abs came on, and held it on for 15 to 30 seconds. This did not stop the car, but slowed it, and allowed me to go straight, until after 10 to 20 seconds, the abs stopped working (no more pedal pulsing, no more abs noise), the wheels locked up, and i slid into the curb. Fortunately, there was no damage. A technician at toyota dealership said it is normal on all vehicles for abs to stop working, and for wheels to lock up, after abs operates for a period of time. This may be what i experienced. He said one should release the pedal and then reapply pressure, or pump the pedal. This suggestion is quite different than the usual instructions, which say to continually press brake pedal. He had an explanation, which i cannot repeat -- something to do with brake fluid depleting somewhere, perhaps the master cylinder. The abs problem problem light has not come on. After that incident, the antilock brakes have worked fine, though i have not tested them in the severe conditions of feb 13. Since the abs system seems to be working now, and the abs light is not on, there appears to be little chance the toyota dealer could do something useful. There appear to be two possibilities: 1. There's a problem with toyota highlander abs systems when applied for an extended period of time. Nhtsa will become aware of this if more owners make reports. 2. The technician is correct that after activating abs for a length of time, one must release the pedal, or pulse it, in order for abs to continue to operate. In this case, instructions for using abs need to be substantially revised, and organizations such as nhtsa ought to inform the public of the issue and the potential for dangerous accidents when abs is applied continuously for too long. |