So i have an Alpine head unit that i have had in the car for like 5 years and never had a problem with it. About two weeks ago i replaced my optispark and ever since then my radio will not turn on. I went ahead and replaced the fuse (15 amp) and when that didnt work i cheched the main battery positve box and negative grounds. Then i actually removed my head unit to check all the wires and my friends told me there is usually a fuse in the back of the head unit but there wasnt one in mine. So i did all this and then realized the new fuse was already blown. I put a new one in and as soon as I turned my key it blew again. You could hear it too.

So does anybody know what could be causing the fuse to blow? Im stuck and dont know what to check next.

 

Anybody have any ideas??

 

Nobody has ever had problems with their radio fuses blowing?

I tried following the black ground wire to see where it grounds but it runs back behind the speedometer and I kinda lost it after that. I tried putting in a new fuse even with my stereo completely disconnected but it still blew the fuse as soon as I turned the key.

 

Ok so i was reading through some other threads trying to do some research and someone had said that if there is a short, most likely its in the aftermarket wiring, not the factory wiring. But even when I have all my stereo stuff disconnected it will still blow the fuse. This is totally beyond me. I am really hoping someone can give me some insight so I dont have to hire someone to look at it.

 

I suspect nobody has responded because the problem is so obvious to most of us that it didn't seem to need a response. I'm sorry that nobody told you.

You have a short to ground in the power wiring for the radio. A bad ground wire will never blow a fuse but a power wire that has bad insulation and is touching ground will blow fuses exactly as you describe. You need to trace the power wire back from the head unit until you find where it is shorting out. It is very unlikely that an undisturbed wire will develop this kind of short so you can probably ignore wiring that is safely bundled in a factory harness. Concentrate on checking areas that have been worked on starting with the adapter harness behind the HU (you did use an adapter harness didn't you?). Then check for anywhere that the wiring might have been rubbing against metal and worn through the insulation.

 

Ok, I was trying to trace the gorund wires back not the power wire. Is the power wire the one i have circled and arrowed in this picture?? And Im hoping this is an obvious easy fix... I would rather it be some stupid mistake I made rather than something expensive to fix!

 

The wire you have circled is your antenna wire and has nothing to do with power or ground. Coming out of most aftermarket stereos: yellow is constant power, red is ignition power, black is ground, orange is dimmer, blue is for amp remote, and the rest are speaker wires (purple, gray, white, green). This is for most Head Units that I've dealt with.

If I remember correctly, the yellow wire from the HU goes to the orange wire on the car harness, which is probably the wire causing the problem.

Maybe try getting a 12 volt tester light and test a few possible power wires to figure out which ones are getting power.

So does it blow the fuse as soon as you install the fuse with ignition off? or when you turn the ignition on?

 

Ok thanks. I was a little confused. It will blow the fuse only when I turn the ignition on, so I will be sure to test that wire. I have a multimeter that I will take with me to look.

 

Ok so I have checked all the wires right behind the HU and I couldnt find anything wrong with them. Do i need to trace the wires back further? They all run together and go behind the speedometer so I dont know where they go after that.

 

Ok so I was looking at this again yesterday and still cant figure it out. I have had several people look to see if any of the wires behind the HU are shorting out and none of us can find any problems. I got a multimeter and checked some of the wires. The yellow wire is getting 12v, and we checked the spot where the fuse goes and it was getting 12v as well. I dont know if there is another spot to check the wires but I lose them behind the speedo.

I always assumed it was just coincidence that this went out right when I replaced my opti, there isnt any way that the opti could affect it is there? The only thing I messed with during the opti install was the positive battery terminal.

Anybody have any thoughts on what to do next or what could be causing this?

 

Please Help Me!

 

There is nothing else to offer in terms of remote help or advice. You have a dead short in the power circuit going to the radio that is causing the fuse to blow as soon as you power up. You'll just have to keep searching until you find the short.

You could just put a piece of heavy wire in place of the fuse and then start watching for where the smoke comes from.

The only other option is to rewire so that the radio is on a new circuit.

BTW, have you tried installing a new fuse with the radio unplugged? It's remotely possible that the head unit itself is blowing the fuses.

 

Yeah I have had it unplugged most of the time and it will still blow the fuse. So I will keep looking for the short, but should I be checking anywhere besides behind the HU? And is there any tricks with the multimeter I can do to figure out which wire is shorting or anything?

Thanks for your help

 

There are only two things the RADIO fuse protects - the head unit and the BCM. You can check with a multimeter but it's not going to narrow it down anymore than that because the two circuits are spliced together and will show the same symptoms.

For future reference, the way to test for a short with a meter is to see if there is no resistance between the power wire you're testing and ground. For example, in this case the power wire in question is the yellow wire in the factory radio harness. Set your meter to either Ohms or to the continuity testing setting (if it has one). Touch the red meter probe to the end of the yellow wire and the black to a clean ground such as one of the bolts under the dash. If you get a low resistance reading or the continuity tester beeps then you know you have a short to ground somewhere on that wire.