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Author Topic: Finding Short in 12 volt Circuit  (Read 198 times)

Heli_av8tor

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Finding Short in 12 volt Circuit
« on: July 20, 2017, 11:11:16 PM »
I have two 12 volt power sockets that are dead. One is in the bedroom and the other by the passenger work station up front. These sockets are fed from a single fuse in the D.C. Power panel, located in the bathroom, in between the two sockets. The fuse is blown.

An ohmmeter shows 0.3 ohms, a dead short from the +12 line to ground. The power sockets are ok. The wire at the fuse block goes into a 1-1/2" sheath and disappears behind the power panel. Nothing obvious there.

I have a schematic for the coach but not a harness drawing/ routing.

Any suggestions?

Thanks, Tom
Tom & Theresa
2004 Pace Arrow 37C
Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

Gary RV_Wizard

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Re: Finding Short in 12 volt Circuit
« Reply #1 on: July 21, 2017, 07:59:40 AM »
Have you isolated which of those two sockets/wires has the short? Since they are at opposite ends of the RV, I'm assuming they have separate wires and there is a Y junction at or near the fuse panel.

Can you run a new wire? That's often easier than finding the bad spot.
« Last Edit: July 21, 2017, 08:01:58 AM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Heli_av8tor

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  • Posts: 121
Re: Finding Short in 12 volt Circuit
« Reply #2 on: July 22, 2017, 08:11:23 AM »
I haven't been able to locate the junction to determine which leg (fore or aft) is shorted.

I really hate the idea of running a new line. I've considered it and may have to resort to that remedy but would rather fix it right.

My hope is that this is a known problem and someone will respond with "look here".

Tom
Tom & Theresa
2004 Pace Arrow 37C
Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

Heli_av8tor

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  • Posts: 121
Re: Finding Short in 12 volt Circuit
« Reply #3 on: July 22, 2017, 05:07:40 PM »
Some progress! I found a connector under the shower that had the wire running to the front power socket.

The circuit from the plug to the front socket is OK. That leaves the wire from under the shower to the power board, to the rear outlet as the culprit.

The load center and numerous other boxes live under the bathroom lavatory. There are no more plug / socket connections that I could find in that maze. I could see where the cable bundle heads back to the rear of the coach. Access is limited and I was not able to pull the wires from the loom to cut and test.

It appears that the loom runs through the rear furnace area. That will be my next area to attempt access.

DW is suggesting I move on to other things. But I just can't let this beat me.

Tom
Tom & Theresa
2004 Pace Arrow 37C
Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

rls7201

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Re: Finding Short in 12 volt Circuit
« Reply #4 on: July 22, 2017, 05:09:26 PM »
I replace the fuse with a 921 bulb and socket, with alligator clips on the leads. The bulb will go out when you find the short.
That way you're not burning up a bunch of fuses.
Richard  & Michele Shields
& Eg the Bounder Cat
Gladstone, MO
95 Bounder 32H F53
460/528 stroker

 

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