Circuit Description
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic test functions on the assumption that a sudden decrease in vehicle speed is caused by a brake pedal application. When the PCM detects that there is a 4.2 km/h (2.6 mph) or greater decrease in vehicle speed within 0.25 seconds and a transition of the TCC brake switch without a transition of the stop lamp switch, the PCM sets DTC P1574.