I just installed a new head unit. I know the wiring is right because I looked at the wiring is correct because I have the wiring diagram for the car and for the head unit. I checked the 12v ignition wire with ground and the 12v constant wire with ground and they both get 12 volts when they are supposed to. I also tried the head unit in a different vehicle and it worked flawlessly. I can't think of any other reason why it wouldn't work. Some more opinions other than mine would be great. Thanks you!!

 

check your fuses

 

Does the headunit have a different startup voltage than its running voltage?
Also it is very possible to have a wire that'll show 12volts but may not be able to flow the amperage required.

Year, make, model, wiresize, headunit requirements pl0x

 

Did you use a conversion harness or did you wire the new connector in with the factory harness? If so that wasn't the brightest thing you've ever done.

 

Well I bought the car used and there was no factory harness or factory stereo. It's a 93 accord lx and the head unit is a $50 dual cheapie