Possible causes

– Faulty stop lamp switch
– Blown stop lamp bulb
– Brake switch harness open or shorted
– Brake switch circuit poor electrical connection

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0504 Description

The Engine Control Module (ECM) has detected a fault in correlation between the two brake switch circuits

P0504 Information for specific makes

P0504 HYUNDAI
P0504 KIA
P0504 SUZUKI
P0504 LEXUS
P0504 TOYOTA
P0504 SCION
P0504 CHRYSLER
P0504 DODGE
P0504 JEEP