wiring from scratch

[csheriff 10+ year member]

hey everybody, im new to the sight, but not new to the stereo wiring world, but i do have a quick question. i am wiring up a stereo for a friend in a Fed Ex truck, and there is no wiring harness to start with, so i have to make my own. i know im gonna need power, ground, speaker leads, but what other wires am i gonna need, and how do i hook them up? any help would be greatly appreciated.

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[KaeZoo 10+ year member]

The easiest way will probably be to find the wire harness leading to the back of the key switch. Use a multimeter to find one wire that has power at all times, and another that has power only when the key is on. Tap these wires for the head unit power wiring. Be sure to use fuses on the new wires to the head unit. These two wires and ground are all you need other than the speaker connections.

 

[csheriff 10+ year member]

which power wire goes to the actual power wire on the cd player, the constant or the ignition on wire? then what does the other one hook to on the cd player? also, what amp of fuse do you recommend?

 

[helotaxi 5,000+ posts]

You will need both constant and switched power to the HU. The size fuse is usually specified by the deck maker. For the constant power lead I would tap into the fuse panel and use a blank spot there rather than tap into the ignition. For the switched lead the ignition is pretty much the only source.

 

[csheriff 10+ year member]

ok, ill be able to figure all that out, one more question, i went and looked at a headunits harness just a minute ago, and there was the dimmer wire hooked up, necissary or not? i dont think so but figured id ask.

 

[KaeZoo 10+ year member]

ok, ill be able to figure all that out, one more question, i went and looked at a headunits harness just a minute ago, and there was the dimmer wire hooked up, necissary or not? i dont think so but figured id ask.

Not necessary to the head unit operation. Its purpose is to dim the display when the lights are turned on, kind of like the factory intrument lighting. In a FedEx truck, he'll probably do most of his driving during daylight hours.