Check The Stop Lamp Switch Circuit.

1. Check that stop lamp lights up when brake pedal is depressed and turns off when brake pedal is released.
2. Measure the voltage between terminal 20 of the ABS control module harness side connector and body ground when brake pedal is depressed.

Specification: approximately B+

Is the voltage within specification?

YES 

• Check the hydraulic circuit for leakage.

NO 

• Repair the stop lamp switch. Repair an open in the wire between the ABS control module and the stop lamp switch.

Fig 1: Checking Stop Lamp Switch Circuit

Courtesy of KIA MOTORS AMERICA, INC.