Component Inspection

Ignition "OFF".
Disconnect brake switch connector.
Measure resistance between the terminal "1, 2", "3, 4" of the brake switch.
Specification :

Resistance between the terminal "1, 2" of the brake switch - ∞ Ω (when the plunger is pushed down), 0Ω (when the plunger isn't pushed down).

Resistance between the terminal "3, 4" of the brake switch - ∞ Ω (when the plunger is not pushed down), 0Ω (when the plunger is pushed down).

Fig 1: Measuring Resistance Between Terminal "1, 2", "3, 4" Of Brake Switch
Courtesy of KIA MOTORS AMERICA, INC.
Is the measured voltage within specifications?
YES
- Fault is intermittent caused by open or short harness in brake light switch, faulty brake light switch or was repaired and HECU memory was not cleared. Go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO
- Substitute with a known-good brake lamp switch and check for proper operation. If problem is corrected, replace brake light switch and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.