i have a 94 integra that im trying to install a head unit . i bought a kenwood new from best buy ,got a new harness and solder the correct color coded wires together, grounded to the frame, turned the key and nothing. radio will not turn on checked ground, checked fuse in the radio checked, for power in the harness with a test light and has power . so i dono why the radio will not work any advice ?

 

there was no ground wire on the harness? also check your ignition wire and make sure you have a good connection. Also, if its like a mid 90's Nissan, the antenna acts as a constant ground for the radio, and thus the ground wire is not needed, so try disconnecting the ground, and see if it turns on with the antenna plugged in. Which model is it? I'm an installer at Best Buy, so maybe I can help.

 

Disconnecting the ground is a bad idea, having it grounded to a solid frame point is a very good idea. All mast antennas will act as a ground but that's not their intended purpose. The reason for that is that they rely on their shield being grounded to help reject noise. Asking the antenna to carry the ground current from the radio isn't a good idea, as it can slightly reduce your radio reception (especially if you listen to AM) and it just not the best ground. Inside the head unit all of the grounds (antenna, RCA, amp, etc..) are connected together so grounding any of them will ground all of them. But depending on the design of the unit you might be asking a tiny little sliver of board trace to carry all of your ground current, which is bad idea. Nissan's did not use the antenna as the main ground, they used the radio's metal chassis which was bolted to the metal frame of the car.
That being said, using a multimeter check the yellow and red wires for voltage while grounding the meter to the same ground point as the radio. Or ground it to the outer chassis of the radio. A test light will tell you something is there, but you need to know that you are getting +12v. A test light can't tell you the difference between 9.2 and 11.1, so it's important to use a meter.

 

you also said you soldered all the wires to the correct wires..

did you solder matching wires? or the right wires?

there are some harnesses/cars that dont match up perfectly. im not overly familiar with best buys harnesses, but it could be something as simple as missing one wire, or connecting one thing to the wrong wire.

power, ground, remote. those are the important ones. get those, and the rest will follow.

 

problem was no power to the red wire .. problem solved thank you for your help .

 

My first suggestion was right. You're welcome.

 

I just want to reiterate this part of Luke's post for future readers; there isn't a single car audio component that a ground is not needed.

 

And let me word it a bit differently to clarify that for anyone that doesn't understand. The antenna is grounded to the body of the car at its mounting point, which grounds the shield inside of the coaxial antenna wire. This grounds the outside of the plug at the head unit, which internally all of the grounds link together - but together does not mean equal!! ALL of the grounds in your car link together at some point, but you woulnd't use the ground from the tailight to ground a 1000 watt amp right? Exact same idea here. Ground everything properly and much less trouble will be had in all of your electrical systems!
Glad to hear your tunes are working now!