# Help with a short on 12v wire



## Bjkbrey (Feb 23, 2021)

So I put a new stereo in my 2005 Toyota Camry a few months ago and it was fine for a while. I used a metra harness and soldered it by hand to the wires coming out of my stereo. About a week ago, I brought my car in for maintenance (just an oil change, filter change, and tire rotation, etc.) and when I got my car back, the stereo wouldn't turn on. I opened it up today and found that there was some sort of short or something, shown in the pictures below. The pin/wire that this was on was 12v power. I don't have a multimeter with me, so I tried to put in my stock radio to see if there was still power going through the 12v wire and it did not turn on. I also went into the fuse box by my steering wheel and checked both of the fuses that go to the car radio and neither of them blew. I'm not really sure where to go from here, does anyone have any ideas on what to do or how his happened? Thanks!

This is also my first post, so sorry if it's in the wrong spot or something.


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## couchflambeau (Apr 18, 2006)

Is the wire affected the 12v Constant or 12v Switched? If the connector is melted/metal scorched and the fuse is intact would make me think the mechanical connection was bad and it arced and heated up. Maybe the adapter harness was poorly assembled and the pin walked back or wasn't aligned correctly?


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## Bjkbrey (Feb 23, 2021)

couchflambeau said:


> Is the wire affected the 12v Constant or 12v Switched? If the connector is melted/metal scorched and the fuse is intact would make me think the mechanical connection was bad and it arced and heated up. Maybe the adapter harness was poorly assembled and the pin walked back or wasn't aligned correctly?


Thanks for the reply, I am pretty sure it is the 12v constant, it is not the ignition for sure. That makes sense because the when I unplugged it from the back of the radio, it did seem to come out very easily, meaning it was probably loose. The only thing that I don't get is why my stock radio didn't work when i plugged it in. The only thing that I didn't connect to it was the steering wheel control plug.


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## Ge0 (Jul 23, 2007)

That melted plug don't look good. I'm just speculating but, perhaps the new radio failed and caused a high current draw situation. Not enough current to pop a fuse but enough to generate some serious heat.

If I were you I would trace that wire back to the fuse block to make sure the wire jacket isn't melted somewhere. This could cause you big problems down the road...


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## couchflambeau (Apr 18, 2006)

Bjkbrey said:


> Thanks for the reply, I am pretty sure it is the 12v constant, it is not the ignition for sure. That makes sense because the when I unplugged it from the back of the radio, it did seem to come out very easily, meaning it was probably loose. The only thing that I don't get is why my stock radio didn't work when i plugged it in. The only thing that I didn't connect to it was the steering wheel control plug.



Generally only one of the two leads will carry the majority of the load of the radio (ie. the amp circuit) which will be a 10 or 15 amp fuse protected wire. Usually the other lead will be a much lower current draw... which depending how they're configured that will either be the "memory/clock backup" or simply just an ignition sense wire to tell the radio to power off when you shut off the car via the key switch. 

If the connector was damaged bad enough the metal tab/connector may not even be seating into the plastic housing correctly so as to make contact. Push the wires individually into the backside of the connector housing to verify they're fully seated. Also verify there's not some other power wire that's supposed to be energized that may have a popped fuse, etc. See if you can track down a diagram that will tell you what ALL of the factory wires are doing since many of them are not used for aftermarket radios. 

Also, if you haven't gotten one... BUY A DMM. They're cheap and take all the guesswork out of basic troubleshooting!


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## Bjkbrey (Feb 23, 2021)

Ge0 said:


> That melted plug don't look good. I'm just speculating but, perhaps the new radio failed and caused a high current draw situation. Not enough current to pop a fuse but enough to generate some serious heat.
> 
> If I were you I would trace that wire back to the fuse block to make sure the wire jacket isn't melted somewhere. This could cause you big problems down the road...


Thanks for the reply, I just bought a multimeter so I'm going to check the wire tomorrow to see if it still has power. If it is melted somewhere and doesn't have any current at the tip of the wire, then I'll trace it back to the fuse. I will also look to make sure the jacket is in tact, as well, that is a really good point. Thanks for the advice!


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## Bjkbrey (Feb 23, 2021)

couchflambeau said:


> Generally only one of the two leads will carry the majority of the load of the radio (ie. the amp circuit) which will be a 10 or 15 amp fuse protected wire. Usually the other lead will be a much lower current draw... which depending how they're configured that will either be the "memory/clock backup" or simply just an ignition sense wire to tell the radio to power off when you shut off the car via the key switch.
> 
> If the connector was damaged bad enough the metal tab/connector may not even be seating into the plastic housing correctly so as to make contact. Push the wires individually into the backside of the connector housing to verify they're fully seated. Also verify there's not some other power wire that's supposed to be energized that may have a popped fuse, etc. See if you can track down a diagram that will tell you what ALL of the factory wires are doing since many of them are not used for aftermarket radios.
> 
> Also, if you haven't gotten one... BUY A DMM. They're cheap and take all the guesswork out of basic troubleshooting!


I bought one yesterday and I'll try it out on the wires tomorrow. I assume there wont be any current, but we will see. As Ge0 mentioned, it could have been the fault of the radio, so I might try to turn it on without installing it into the car and seeing if it's junk now or what. I did look at the internals of it and it doesn't look like anything on the circuit board has melted, but I don't want to just throw it back into my car to have the same thing happen again unless I can tell it works as normal. 

As far as checking other fuses, I only saw two fuses that were labeled as 'car radio' in the schematics here but I could pull them all out and take a look if you think it is possible that it tripped another. It wouldn't take too long.


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## Holmz (Jul 12, 2017)

Bjkbrey said:


> Thanks for the reply, I just bought a multimeter so I'm going to check the wire tomorrow to see if it still has power. If it is melted somewhere and doesn't have any current at the tip of the wire, then I'll trace it back to the fuse. I will also look to make sure the jacket is in tact, as well, that is a really good point. Thanks for the advice!


Those multimeters also work as a way to find shorts... 

One can also measure current draw with some of them, which can aid in understanding what the radio is drawing.


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