One problem related to wiring has been reported for the 2004 Ford Mustang. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Ford Mustang based on all problems reported for the 2004 Mustang.
The top of the clutch pedal assembly when depressed and released rubs the wiring harness to the brake switch, neutral safety switch and others shorting out the brake lights and making the cruise control inoperable. It works for a while but then it blows the fuse again and someone has to stop me and tell me my brake lights don't work. The dealer has replaced one of the wires for the brake switch which is in that same wiring harness and says the problem is fixed but sooner or later it will rub the rest of the wires bare too. I have also replaced the brake switch a couple times because when it shorts out it melts it if the fuse doesn't blow right away. I am afraid one time someone will rear end me or I will get a ticket.