P0504 GMC Brake Switch Circuit A / B Correlation
Possible causes
– Faulty stop lamp switch
– Blown stop lamp bulb
– Brake switch harness open or shorted
– Brake switch circuit poor electrical connection
– 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 GMC Description
In addition to turning on the stop lamp, the stop lamp switch signals are used for a variety of engine, transmission, and suspension functions as well as being an input for diagnostic checks. It is important that the switch operates properly, therefore this switch is designed with two complementary signal outputs: STP and ST1.
The Engine Control Module (ECM) analyzes these signal outputs to detect malfunctions in the stop lamp switch.
GMC Vehicle:GMC Acadia,GMC Canyon,GMC Envoy,GMC Savana 1500,GMC Savana 2500,GMC Savana 3500,GMC Sierra 1500,GMC Sierra 2500 HD,GMC Sierra 3500 HD,GMC Terrain,GMC Yukon,GMC Yukon XL 1500,GMC Yukon XL 2500,