Audio Systems: acc wire ?, fuse panel, fuse holder

Question
i have a 98 ford expedition with the mach stereo,i recently purchased an amp and sub box. i am having trouble figuring out which wire is the acc,if you could help me find it,it would be gretly appreciated.

Answer
Use a meter to find which wire only has power when the car is ON.

An alternative...

Run a fused (1 amp, 14 AWG) wire from a fuse in the fuse panel that only has power when the car is ON to one side of a switch (toggle or rocker). From the other side of the switch run the same wire to the REM connection on the amp.

This allows for full control and you never have to worry about forgetting to turn off the amp.

You can get an in-line fuse holder and fuse taps from any auto parts store.