Fuse in fuse box blowing. 2 in 2 days.

[bikinpunk 10+ year member]

I don't know what is causing it. I'll be driving and the cd player will simply power off. It's happened twice in 2 days and it's the same fuse (radio fuse) in the panel box. I've never had this trouble before. I also haven't changed or done anything to my stereo system in at least 2 months. As soon as I replace the fuse, everything's back to normal. I thought about upping the amperage from 7.5 to 10 to see if it helps. Any ideas what could be causing it?

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[bikinpunk 10+ year member]

Anyone?

 

[KaeZoo 10+ year member]

Do not up the amperage. The radio fuse is usually the accessory fuse, and an aftermarket radio shouldn't be drawing more than 1 amp. So if fuses are blowing, it's probably the result of a short, and replacing with a larger fuse will do no good and might do some harm.

Pull the radio and check the red and yellow wires for bare ends, or evidence that they're being pinched. Tape up or repair any loose ends or damaged wire.

Edit: Sometimes the "radio" fuse is the constant fuse for the CD player; in that case, a problem like a shorted speaker wire or blown speaker might cause the fuse to blow. Do you have access to a test light or multimeter? Finding out whether the fuse is constant or key-switched may help determine where to look for the problem.

 

[cyantist 10+ year member]

Most likely a wiring problem.. Although a deck can draw up to 10 amps (depending on the deck and if you're using the internal amp), it doesn't make sense that this just started happening..

 

[bikinpunk 10+ year member]

I have a DMM. How can I test the fuse panel for draw? Just put the positive end of the DMM into where the fuse goes, and ground the DMM at some metal point on the frame?

I figured I could turn the car on, do this, and see what kind of current I'm getting to the fuse. However, will it work sine there's no fuse there?

No speakers are blown. It boggles me that it's doing this all of a sudden, with no warning. I'm wondering if something is wrong in the fuse box itself, considering it's a brand new car and the fisrt year build of it.

 

[cyantist 10+ year member]

I still think the culprit is in your dash.. Wires can easily get pinched when you're installing a deck, and with all the vibrations in a car, well, you know.. I think this is where you are going to find the problem..

You don't have to take out the fuse to take the measurement you're talking about.. You can still measure it with it in there, which is going to be the only useful measurement you can take since you will have to run your system to determine the amperage draw..

Anyways, what make/model deck is it? Are you running speakers off the deck?

 

[KaeZoo 10+ year member]

You don't have to test the current draw at the fuse holder. Just use the DMM to find out whether that fuse has voltage all the time, or just when the key's on. That will determine which wire at the head unit may be causing the problem. If it's key-switched, then it's the red wire, and it shouldn't be drawing more than 1 amp. If it's constant, then it's the yellow wire.

Once you determine which wire to focus on, you can try disconnecting it from the factory wire and run it to a different source (which also needs to be fused). This will let you find out whether the problem's in the factory wiring or the radio.

 

[bikinpunk 10+ year member]

I have an Alpine iva-d300. I'm running rear speakers only off the deck. The fronts are powered via external amplifier.

How do I connect the DMM to fuse holder? So, I should do this both with the acc on & off to determind if it's constant or switched power? I understand what you're saying, I'm just not sure how to actually attach the DMM to the fuse holder?

 

[KaeZoo 10+ year member]

You don't need to attach it. If you look closely at the top of the actual fuse you'll see the metal tops of the two spade "legs". You can access these with your DMM probe without removing the fuse. Set your DMM for DC volts, ground the black probe, touch the red probe to the top of the fuse. If it shows voltage, it's a constant circuit. If it doesn't, then switch the key to "accessory" and try again.