Plug and play with Holley EFI and Terminator X main harnesses 2007+ PWM GM alternators Use with late model OEM alternators Include detailed instructions for installation and software configuration For use with 2007+ PWM GM Alternators.. Plug and play Holley EFI alternator harnesses for late model engines with Pulse Width Modulated alternators. This includes most 2007+ GM engines and most 2005+ Ford engines.