Originally Posted by ken99

You asked a question and I tried to answer it without getting too specific. So you think the brake light switch has nothing to do with your car's ABS system? The attachment is the basic wiring schematic of the ABS system to your Sonata. In the upper right hand quadrant you will find the 15A "STOP" fuse listed. Below that is the "Stop Lamp Switch". If you trace the wiring down from the switch, it branches at a joint connector providing a feed to the stop lamps at the back of the car, and a feed to the ABS module. Hmmm. Wonder how the ABS initially knows that you've applied pressure to the brake pedal? Yes, the brake light switch feeds current to a logic circuit in the ABS module that activates the ABS to start monitoring the wheel sensors before you've depressed the pedal far enough to build significant line pressure to the brakes. A similar connection exists between the switch and the ESC, since it needs to know if you are applying brakes as it compensates. Also that little brake light switch is wired to the cruise control system, signaling it to disconnect when you apply the brake. The brake light switch also controls the lock out solanoid that engages when you place the automatic transmission in Park. Since it is wired to and controls so many systems in the car, I would say "yes", the brake light switch is integral to the systems it is connected to and involved with.


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Originally Posted by NovaResource

One of the wheel sensors might be going bad. They are located on the hub of each wheel.