Have your Daytime Running Lights gone out?  This is an on going problem of which GM is aware. Daytime running lamp bulb replacement. All 99 up GM trucks. Replace it with the  14 volt DRL bulb, P/N 15199562 (trade bulb #4114K).  This more robust, higher voltage DRL bulb replaces P/N 1999482 (trade bulb #4157K). These [...]