Circuit No. 5 Mystery

[Leaford]

I have a 2005 Safari that has developed an odd electrical problem. All the electrical devices on the circuit that feeds the thermostat, bath lights, and the fantastic fan have become inoperative. However, the fuse that serves that circuit from the DC panel has not failed. I have replaced it anyway with a new fuse, and no change. I have also tried moving the wire that directs the current to this circuit to another fuse location, still no change...everything is still dead. Immediately prior to the circuit going dead, the bathroom lights flashed as few times. Does anyone have any suggestions for a fix?

[Wabbiteer]

1st - Welcome to the forumns! From chatting w/ Leaford in the AirForum online chat the circuit went dead while camping in very hot and dry area - anyhow electric storm almost here now, have to close down PC and trailer

[lewster]

Originally Posted by Leaford

I have a 2005 Safari that has developed an odd electrical problem. All the electrical devices on the circuit that feeds the thermostat, bath lights, and the fantastic fan have become inoperative. However, the fuse that serves that circuit from the DC panel has not failed. I have replaced it anyway with a new fuse, and no change. I have also tried moving the wire that directs the current to this circuit to another fuse location, still no change...everything is still dead. Immediately prior to the circuit going dead, the bathroom lights flashed as few times. Does anyone have any suggestions for a fix?

Sounds like you have NO POWER in that circuit. If switching to another power lug gives no power, then there must be a break in either the +12VDC feed or in the return ground. Did you check the ground side of the circuit?

See if you can isolate either and do a continuity test (with the circuit removed from the power) to all of the effected appliances. If they are connected in parallel, a break will be evident when the continuity stops.

[TitusLivy]

A couple of ideas come to mind.

First, it's unlikely that the "hot" wire for that circuit (the one protected by the fuse) is shorted to ground, because if it were, the fuse would blow.

Second, since a short seems unlikely, the most plausible explanation is that 12 VDC is not being applied to the "hot" wire. This might be due to a problem within the converter, where the fuse is located, or a problem with the circuit after it leaves the converter and heads toward the lights, etc.

To test this idea, open the converter to expose the fuse, and use a voltmeter to measure the voltage between the fuse and ground. The circuit ground should be easy to find...look for a large black wire. Also, the ground may be explicitly identified on the converter's fuse board. Be careful, both to avoid shocks and to avoid "shorting out" any of the converter's components. You should get a reading of about 12 VDC. If you don't, then that circuit is not receiving the proper voltage, and you should direct your attention to the converter itself. Be careful!

On the other hand, if you see that the converter is applying 12 VDC to that circuit (as it should), then there may well be a problem with the wire that carries current from the fuse to the lights and appliances on that circuit. To determine whether that circuit is intact:

(1) remove the fuse in order to open the circuit

(2) also, "complete" the subordinate circuits (for the fan, lights, etc), by turning on their switches. The goal is to electrically complete the circuit's "hot" wire so you can test it to see whether it's continuous (as it should be) or broken.

(3) open up one of the appliance's on that circuit (fan, lights, etc) to expose its hot wire, and disconnect it.

(4) now use a multimeter to measure the resistance along that wire from the fuse to the exposed "hot" wire. In other words, put one lead of the multimeter on the open fuse holder (on the "downstream" side of the fuse), and put the other lead on the exposed hot wire. You may need to rig up an extension to lengthen one of the multimeter's leads to do this. If the circuit is intact, you should read zero (or nearly zero) resistance. If not (that is, if you see a substantial resistance), then this circuit is "open". In other words, a wire is broken or there's some loose connection at some point along the circuit. In that case, you'll have to trace the hot wire to find it...and that may be a trick, since accessibility will be limited.

A final possibility is that 12 VDC is being applied to the circuit, and the circuit's "hot" wire is continuous, as it should be...but the ground wire(s) for that circuit have come loose so that they're "floating". I think this is unlikely. But if everything else checks out, then with the fuse in place, open up one of the devices on the circuit (a light, for example) to expose it's "hot" and ground wires, flip the switch in an effort to turn it on, and measure the voltage between the "hot" wire and the ground. It should be 12 VDC. If not, then verify that the "hot" wire is receiving 12 VDC relative to the "system ground" within the converter. If that looks okay, then I'd start focusing on the possibility that there's something wrong with the grounding for the devices on that circuit. I'd begin by measuring the resistance between the open device's (light, fan, etc) ground wire and the "system ground" at the converter...it should be essentially zero. If not, then the defective circuit is not properly grounded. I'll be surprised if that's the problem.

I'm sure there are other possible explanations for your problem, but I hope these ideas help. Go slowly when you're working with electricity, and make double sure you understand what you're doing before you do it.

Good luck!

Titus

[SRoffe]

Originally Posted by Leaford

I have a 2005 Safari that has developed an odd electrical problem. All the electrical devices on the circuit that feeds the thermostat, bath lights, and the fantastic fan have become inoperative. However, the fuse that serves that circuit from the DC panel has not failed. I have replaced it anyway with a new fuse, and no change. I have also tried moving the wire that directs the current to this circuit to another fuse location, still no change...everything is still dead. Immediately prior to the circuit going dead, the bathroom lights flashed as few times. Does anyone have any suggestions for a fix?

Titus gave a good run down on what you should do. Just one other question, are there any devices on that circuit that do work?

You might want to look at each device and see if the 12V+ came loose and thus everything down stream (electrically speaking) would not have power.

Sam

[TitusLivy]

Another quick thought. Please be careful, because electricity bites, sometimes badly. So since your problem is with a 12 VDC circuit, I would definitely disconnect shore power before trying to figure this out. Running off of the house batteries should let you do all the tests needed to find the problem, while reducing the risk that you'll bump into 120 VAC someplace where you don't expect it. Be mindful that your inverter (you no doubt have one) will still be producting 120 VAC...so watch out around any circuits it powers.

Good luck, again!

Titus

[Leaford]

Thanks for all your suggestions. They are clear and helpful.

[Excella CM]

Look at the first appliance and switch downstream from the fuse. Put the wire back on.

[Beaverstream]

Originally Posted by Leaford

I have a 2005 Safari that has developed an odd electrical problem. All the electrical devices on the circuit that feeds the thermostat, bath lights, and the fantastic fan have become inoperative. However, the fuse that serves that circuit from the DC panel has not failed. I have replaced it anyway with a new fuse, and no change. I have also tried moving the wire that directs the current to this circuit to another fuse location, still no change...everything is still dead. Immediately prior to the circuit going dead, the bathroom lights flashed as few times. Does anyone have any suggestions for a fix?

Did you ever get this fixed? My 2011 Flying Cloud is doing the exact same thing on the same circuit.

[Bigventure]

I'm thinking low power and the breaker tripped, but not fully. I would start with turning each breaker off and resetting each one. Hot and Dry are what trips my trigger. The campground power was low.

[Aage]

Welcome back to 2007 (that's when this was posted).

If you want to know, try emailing the original poster, they might have used a valid email address...

In the meanwhile, read TitusLevy's post, #4 in this thread. He gives the exact steps a mechanic would use to troubleshoot your problem, while you would be charged $125 or more an hour to do it.

Good luck with your sleuthing!