Mystery wire

[ACDNate]

2008 Winnebago Journey 39z

I picked this motor home up a couple weeks ago now. Been going through everything making sure all is up to snuff. Bulbs, clean up etc

Upon investigating the battery compartment I found a large gauge wire tucked behind the batteries. Wire is black but the terminal appears to be painted red.

I broke out the multi-meter to see what's what.

Taking the positive meter lead to the terminal of the mystery wire and grounding to chassis and battery ground I got no voltage.

Taking the positive lead to the battery and negative lead to the terminal of the random wire shows 13ish volts.

So my gut says this is a ground wire. Not sure why its not tied in. First instinct is to bolt it on to a ground terminal and go. But I don't want to screw something up.

Any suggestions???

[wa8yxm]

TNGW1500SE wrote:
"If it ain't broke, don't fix it"

It everything works why attach it? I'd trace it.

On a motor home there are some systems that are "Always HOT" if this wire runs to one of 'em then it will meter exactly as you observed.

As TNGW said. if everything works, Do nothing

IF one circuit does not work Here is a SAFE way to apply power to that lead Method 1 and 2. 1 is for low current draw loads. 2 for big ones

Go to Auto-parts store (if you don't have one) and get a 12 volt Ice Pick.. Well Test light. this looks like an old fashion ice pick with a wire coming out the handle and a light bulb inside the clear or translucent handle. Hook the clip to the wire under discussion and touch the battery plus. BRIGHT light indicates you may need a bigger lamp.. DIM good. start looking for something that did not work that makes it bright.

Method 2: Use a bigger bulb.. Like a head light from a garden tractor. Or a 100 watt (my favorite) 12 volt Trouble Light.

This is a standard looking light bulb, like a 100 watt screw in 120 volt lamp. but it's 12 volts. the "Drop light" has battery clips where the plug belongs. Have also seen one with a standard plug and an outlet with battery clips

Don't want to invest in teh entire 12 volt trouble light?

A tunnel light socket and a couple of battery clips and the 12 volt bulb.

[ACDNate]

MountainAir05 wrote:
meter on ohms and one lead to wire and the other one to chassis ground. If its connected to a ground you will get a reading. If not it is not connected to ground.

Thanks

[Dr_Jay]

Have you ( or can you) speak with the previous owner. He/she msy know the answer.

[MrWizard]

The ohm symbol , the Greek letter Omega
represents resistance
You want to measure resistance, aka a continuity check
To see if the wire is connected directly to ground, almost zero only a few ohms resistance
Or whether you are reading thru a device

[MountainAir05]

meter on ohms and one lead to wire and the other one to chassis ground. If its connected to a ground you will get a reading. If not it is not connected to ground.

[ACDNate]

mccsix wrote:
did you use the ohm side to ck the wire to ground?

Not familiar with this. More details please?

[mccsix]

did you use the ohm side to ck the wire to ground?

[ACDNate]

It doesn't appear to be an aftermarket add on. It's a large gauge wire, think battery cable.

Also not everything is 100% I have an intermittent inverter/charger issues. Can't be certain the two are related.

Any other testing methods to confirm the cable is a ground?

[IBcarguy]

Previous owner may have had some kind of 12v power accessory that he removed before selling it. Based on your test, it's a ground wire and if everything seems to work, don't worry about it.

[TNGW1500SE]

"If it ain't broke, don't fix it"

It everything works why attach it? I'd trace it.