onecrazyfoo4u

So I disconnected my battery terminal the other day to do some other work. After hooking it back up my head unit doesn't work anymore. I checked the fuses in the engine bay and down by the clutch pedal...all fuses are good. I saw one inside that was labeled radio and one in the engine bay labeled radio, both were good. I even swapped them with brand new fuses just to be sure; still doesn't work. Then I pulled the head unit out and checked replaced the two fuses on the head unit itself (even though both fuses were good). Still doesn't work.



All 4 fuses on my sub amp are good too. Where do I start looking next? Radio doesn't turn on and amp doesn't turn on either (probably since the remote wire coming from the head unit isn't active). Is there a hidden fuse/switch somewhere to check? Everything else electrical works fine.

SR Tech

Did you check for power at the back of the head unit when you replaced/checked the fuses? Should be power at 2 wires back there, 12v source(normally red) and 12v memory(normally yellow)



Some radios have theft deterant codes so when the battery is disconnected or dies, the head unit requires a code that comes with it when you buy it to get it to operate again, but it will turn on and ask for the code.



But it sounds more like its not turning on at all correct?

onecrazyfoo4u

Yeah not turning on at all. Its some cheap aftermarket radio. I'll check for power coming out of the radio harness and see what I get.

onecrazyfoo4u

Getting 12.6v before and after the inline fuse and at the harness that connects to the head unit. This is for both the yellow wire and the red wire (with key on only). Yellow wire is always 12.6v. So I guess the cheap boss head unit is finally fried. Gives me an excuse to finally buy a nice alpine or something.



Is there anything else it could be if both wires are getting power to the stereo?

tibbytib

I'd double check your ground. Did you use the ground from the stock stereo harness? I had to use a seperate ground as the stock ground was inconsistent and actually fried an aftermarket stereo I had.

onecrazyfoo4u

I actually used the ground from the wiring harness connector output to measure the other voltages. So I would assume that means its good??? I'll have to doublecheck the ground though. The stereo came with the car...so not sure what ground he used.

SR Tech

If you have power at both red and yellow wires and a good ground, all at the unit, I'd have to agree that it is bad.



The fact that it happened after a battery disconnect may just be a coincidence.

Stocker

It almost never happens bad enough that it's a problem, but...



When you break a low voltage line with current running through, the magic of electricity sometimes turns the small amount of power flowing through the wires to a high voltage very low current pulse. This can be enough to kill some electronics. If the radio was playing while the battery was unhooked, and it suddenly stopped, AND you are going to get a better one anyway . . . you killed it.