Blowing 15 amp DC Fuse

[mscott4378]

I have a hardwire 12-volt rear camera and a set of 12-volt ultrasonic mouse deterrent devices on one of the extra 12 volt fuses on the fuse panel. I have run a coax cable from the rear of the trailer to the kingpin and use a quick connect coax connecter to connect the video feed to the truck. These have been working fine for the past 6 months with no issues. Actually, the camera portion has been working this way for the past 3 years. I add the mouse deterrent devices 6 months ago. In the past two weeks, the 15 amp fuse is blowing after about 10 -15 minutes of turning on the rear camera and hooking it to the coax connecter which occurs on travel days. We leave the mouse devices on all the time. I have tried reading the amperage with my dc amp meter, but it only shows 1 amp. I could use some guidance on how to debut this one. My next step is to run new wiring from the main garage back to the top of the back tail lights where I installed the camera. The camera 12-volt wire is using 14 or 12 gauge spearker wire.

 

[6.7LMegaCab]

The speaker wire has rather thin insulation to hold up against chafing, so maybe it wore through somewhere? Use a multimeter to check for a short on the +12V going to the camera from the fuse panel. If it's taking a while, perhaps it's intermittent and only happens when moving.

I would replace that wire with automotive stranded wire which has thicker insulation.

I don't think the coax would have anything to do with the fuse blowing as it only serves as a signal path for video.

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[wdk450]

I have previously troubleshot the 12 VDC circuit to my refrigerator and rangetop light/fan which kept erratically blowing. My tactic was to temporarily wire in in-line fuses of a opening amperage (5A.?) much less than the main 15 A. fuse, near the loads or suspect wiring. With this setup, if the main fuse again blows, the problem is between the main fuse and the smaller fuse(s). If the smaller fuse blows, the problem is beyond (downstream) of the smaller fuse. Once the problem is discovered and corrected, the additional fuses can be removed from the circuit.

Good Luck!!!

BTW, I learned that my refrigerator 12 VDC problem was a supply wire from the fusepanel wrapped TIGHTLY around a metal base corner of the refrig, causing the insulation to rub away, and the conductor to intermittently short against the grounded metal refrigerator base with road vibrations, blowing the main fuse.

 

[6.7LMegaCab]

Just learned something new. I've always preferred to shoot the wires. Good tip!

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