how can i make my kenwood cd player work in my ford fiesta l?

Did you connect all the wires correctly? you checked all the fuses? have you tried connecting it up solely, i.e. without the speakers / amps etc, to see if the problem is with the power supply to the head unit, coz maybe the speakers are shorting and there is a protection circuit in the head unit which stops it turning on.

HTH

/////ALPINE
December 2004