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04 FXT
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Discussion Starter #1
Was driving and my radio and clock shut off. When I parked and tried to lock the car with the clicker, it wouldn't work and while driving now, the security light flashes on and off. Tried putting in a replacement fuse in the clock spot which was blown, but as soon as I put a new one in (with the car off) it sparks and blows. Went through 3 fuses already trying it and looking at the wires and fuses I can see.

I assume there is a wire that is rubbing or touching something causing it but just wondering if anyone knows how I could narrow it down and save some time over searching the whole car til I find it. :biggrin:
 

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2004 Forester 4EAT
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Usually a short in a component rather than a wire. I would first disconnect the radio. You'll have to pull the dash apart to get to the plug. Do you have a stock radio? Do the interior lights work? Could be a problem in one of the door switches. Doubt it's the clock, but you never know.
 

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Discussion Starter #3
I have an aftermarket radio, sub, and amp. I don't think the problem has to do with clock, just that was the fuse I was trying to replace. I assume it has something to do with another wire somewhere but I don't know where. Checked the amp already and everything was fine. Going to pull the dash apart and check the radio tonight.
 

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2018 2.5i Premium CVT
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It's not the door switches. There are no hot wires associated with these switches. Their job is simply to ground the wire from the dome light controller ('integrated module') when the door is open. Worst that could happen there is that the wire got loose and brushed up against a nearby ground. Light would come on.

These are all the things listed as being controlled by that fuse (lifted from the shop manual in Subaru-speak, with translation where appropriate).
Auto A/C control module
Clock
Combination meter (odometer etc.)
Integrated module (dome light controller)
Luggage room light
Radio
Room light
Security control module
Security horn relay
Spot light (map light)​

I'd start with the easy ones (map, dome, and rear compartment lights), pull them out (not difficult), and look for something amiss.

A modified 'smoke test' might also be useful. Get an assistant with good hearing, go out when it's dark, drop in a new fuse, and see if the assistant can spot something—a brief flash or a zap sound.
 

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How's your amp wired, power from battery? Most probably in radio.
 

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Discussion Starter #6
It's not the door switches. There are no hot wires associated with these switches. Their job is simply to ground the wire from the dome light controller ('integrated module') when the door is open. Worst that could happen there is that the wire got loose and brushed up against a nearby ground. Light would come on.

These are all the things listed as being controlled by that fuse (lifted from the shop manual in Subaru-speak, with translation where appropriate).
Auto A/C control module
Clock
Combination meter (odometer etc.)
Integrated module (dome light controller)
Luggage room light
Radio
Room light
Security control module
Security horn relay
Spot light (map light)​

I'd start with the easy ones (map, dome, and rear compartment lights), pull them out (not difficult), and look for something amiss.

A modified 'smoke test' might also be useful. Get an assistant with good hearing, go out when it's dark, drop in a new fuse, and see if the assistant can spot something—a brief flash or a zap sound.
Will do. Thanks.

How's your amp wired, power from battery? Most probably in radio.
Yes from the battery. Something with the radio is my guess too.
 

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2018 XT Touring CVT
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Instead of blowing lots of fuses until a fire starts, why not use a few larger fuses? You can start a fire quicker.

Finding Shorts

Instead of blowing lots of fuses until a fire starts, use pins to make the fuseholder terminals accessible.
Do not let the pins contact each other. I made an extender from a blown fuse, solder, and wire.

Connect a 12V testlight or lamp to the pins. If the light is full brightness, you still have a short.
This puts a lamp with plenty of resistance in series with the short circuit.
The lamp is an indicator and current limiter, and is replacing the fuse.

You can then disconnect stuff and observe the light.
 

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Discussion Starter #8
Thanks everyone. Got it fixed. The radio was the culprit. Not sure what was touching but I retaped the connections back there and voila, it works.
 

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2007 Mitsubishi Pajero 5spd Automatic
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Instead of blowing lots of fuses until a fire starts, why not use a few larger fuses?
Or use pins/paperclips to make the fuseholder terminals accessible.
I made an extender from a blown fuse, solder, and wire.

Connect a 12V test light to them. If the light is full brightness, you still have a short.
You can then disconnect stuff and observe the light.
Now that he found the problem it's ok. But for what it's worth I don't like your way of going about such a problem. I get your point but when working with electricity I think this is a bad idea.
Short circuiting creates higher current draw then normal and this can if you ignore the fact that the fuse is blowing, melt wire isolation/start fire, damage the battery or other stuff in the car.
Just my 2 cents. Sorry m8.
 

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Putting a light made for 12 volts in series with a shorted circuit does not cause a problem. It limits the current to whatever the bulb draws at 12V.
 

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If you're putting a test lamp in series with the circuit, the size of the fuse is irrelevant; all the short-circuit current is dissipated in the lamp...
 

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Using this method, you are using the lamp as a indicator and a current limiter, and it is replacing the fuse
 

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Using this method, you are using the lamp as a indicator and a current limiter, and it is replacing the fuse
I did not read that. I just got the part about putting in a bigger fuse. Sorry
 

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Sorry guys, but as a service tech, I feel you are all over thinking this. 15 years of chasing down problems has taught me to go to what has been modified first. It's almost always the case. Fuses are there for a reason. I agree with your test light theory, but messing with the amount of current going through your fuse box is something best left for auto electricians. I would rather start unplugging things till the problem goes away. Just my $.02
 

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You need to substitute a lamp for the fuse while testing, otherwise you blow a fuse after each wrong guess.
You are not increasing the current in the fusebox this way.
 

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2018 2.5i Premium CVT
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Glad you were able to track it down.

@jgrote: Good observation about first suspecting the mods. It's not unreasonable to assume that the original designers might have put a bit more thought into things like routing of cables and integrity of connectors than would somebody who dropped in an aftermarket mod.
 
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