Make sure it's grounded as well. The best way to do this is with a meter, because a simple test light may not be telling the whole story.
If you don't have a meter, go buy one..even a cheap one is better then nothing.
Set the meter for voltage DC in the range you need (most meters lowest setting is up to 20v dc)
Place the negative probe on a solid ground. Take the positive probe test for your accessory and constant. make sure it reads at least 12v. If not check the fuses until you do. Sometimes wires get damaged so you may have to run a new one from the ignition harness, but it's rare.
Now once you know the power wires are good look for the ground (don't confuse this with the illumination or dimmer which will show ground with the lights off). Test with the positive probe on the constant and negative probe on the chassis of the deck. If it's at least 12v the deck should power up. If not..suspect a defective head unit.
Hope I helped.
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Have you verified there's not something wrong with the unit itself? Connect the constant/switched wires in the new stereo's harness together and touch them to the positive battery terminal. Connect the ground lead to the negative terminal. If the unit does not come on, and the fuse is good, the unit is bad.
Is the factory radio harness still there? If so, pick up a harness from a local shop. That way you can wire it to your new deck and plug it into the factory harness. If the plug has already been hacked off, read the sticky "How to figure out stereo wiring".
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My ex once told me I have a perfect face for radio.
hey thanks for the tip on testing the deck. it powers up. no the original harness was cut. my wire colors arent matching up the wire digram. i'll try the voltmeter approach to try to find the power wire. thanks again guys.