Diagnostic Aids
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
DTC P1574 indicates the stop lamp switch signal to the EBCM or the EBCM's ability to send the stop lamp switch signal to the PCM has failed. Refer to ABS/TCS DTC's for diagnosis of the stop lamp switch signal and the EBCM.
Courtesy of GENERAL MOTORS CORP.