I got in my 1990 4runner 3.0 yesterday and my radio didn't come on, checked the fuses and they were fine.(under the hood, under the steering wheel and on the back of the head unit) I then checked to see if there was power using a test light and there was 12v from battery and from ignition. Is my head unit bad? I think that is the only option but I'm not sure. Thanks guys

 

If it has power and it has ground, it needs serviced or checked out might just be a bad switch who knows. You've done your part, it's like growing flowers water+dirt+light and the rest is upto the plant.