Randon 12 volt cutoff to Refrig, H20 heater, furnance, but then starts working again

[tomyoda]

New on forum but I have read many threads for other issues and when working on other issues.

I have a 2008 Damon Tuscany 4056. I have had the rig for 19 months. I have an intermittent problem with 12 volt supply to refrig, furance and water heater. These are all on the same fuse. The fuse is good.
When the 12 volts is working there is 12 volts across the empty fuse holder. When the issue is happening, the voltage is about 1.8 volts.

Refrig is Norcold 1210IM
H20 heater is Atwood GE16EXT
Furnance unknown brand. It is controlled by Carrier AC unit remote control or button push on AC unit. Temp control on AC ceiling thermistat.

The rig has control switch for Electric(120V/AC) and Gas control switches on the front control panel. When the issue happens the light in these switches does not light even if the switch is in the on position.

When the issue first starting happening. I happened to discover that flipping the propane cutoff switch on the front control panel solved the issue. I have since found that does not resolve the issue. I also found pulling and replacing the 12 V fuse for the propane cutoff switch would solve the issue.
Now none of those are resolving the issue now.

The issue happens when the propane tank is full, half full or 2/3 empty.

When the issue is happening, I have tested AC unit control of furnace. I hear the control click when the thermistat switches to call for heat.

The issue can start when all three appliances are working just fine. It could be just the refig and H20 heater are turned on and Furnance is off. I think it has even happened when just the refrig was on.

The 12 V fuse panel is progressive Dynamics and has red lights beside each fuse. When the issue is happening, I have pulled the fuse and the light is very dim compared to when the issue is not happening.
I have moved the line in the back of the fuse panel to an unused fuse spot but the light is still dim and only 1.8.

All other 12volt systems are getting power when the issue is happening. ALL, LOL. h20 pump, interior and basement lights, bedroom radio fantastic fans, slides.

I saw someone posted some electrial diagrams of the same coach on the IRV2. Thanks it is the HPE circuit on that diagram which is 12 volt fuse no 5.

I am planning to take it in to a shop but I think they will have as many issues troubleshooting since the issue cannot be forced on demand or fixed by a specific process.

I do not understand how the propane valve cutoff switch or fuse are involved that have fixed the issue sometimes.

Any thoughts on what is causing the issue.

Tom

[Kiawah]

I don't have your coach, so can't give any specific info.

If this were my coach however, there are a couple things I'd try to narrow down where the problem might be. I'd make up a set of new long power wires, a positive and a negative, that I could use for testing.

Negative wired to the negative of the battery post. When used for testing, this will eliminate/confirm the possibility of a bad/intermittent ground cable somewhere causing your problem.

Positive (with fuse) wire to the positive of the battery post. When used for testing this will eliminate/confirm that the positive is the problem.

Next time you get a failure on one of those devices, use your negative test cable and apply the ground directly to the failing device. If the device starts working, you know the problem is a ground problem. You can also measure the voltage between the new test negative lead, and the existing device negative. If there is any voltage, it's telling you there is a resistance somewhere (resistance will drop voltage).

Then you can use the positive test lead to power the device directly. If the device starts working, then you have confirmed that the problem is the power supply line to that device. At that point, you'll need to follow the wiring back to figure out where it's going bad.

Good luck.

[tomyoda]

That is great idea. I was thinking of trying to run the frig or furnace off a cable from the battery. I did not think about using it to test the ground or voltage. I am heading to lowes/h depot to get the long cable. I thought I had some in the coach but I cant find it when I need it.

I did disconnect the furnace, frig and h2o heater hot wires and then checked the voltage across the frig wires. 9 volts. So obvious voltage drop somewhere.

I will update once I get the cable to do more testing from the direct battery connection.

Thanks for the ideas.

Tom

[tomyoda]

Another update.

I connected my test wire to the positive of the battery. I then checked the voltage across the test wire and the 12 volt wire to the refrig. reading 12 volt. I thought, what the. Did I connect something wrong!

So I checked the voltage between positive test wire and the refrig ground wire. reading 12 volts. OH, light goes on.

So no voltage on the 12 volt line.

I then checked the voltage across the test wire connected to the battery post negative and the refrig ground. 0.00 volts.

I then checked the voltage across the negative test wire and refirg 12volt line. 0.00 volts.

Based on that, I connected my fused postive test wire to the refrig 12volt and the refrig ground. We have ignition. Refrig control unit is working. WOOHOO. We have cooling.

Furnace testing.

I did the same refrig testing above on the furnace and got the same results. After connecting the positive test wire to the furnace 12 volt. I triggered the thermostat to turn on the furnace. WooHOO We have heating.

H2O heater testing.

Holding off testing because when I was doing the above testing on the furnace. I heard the H20 heater turn on at the back of the coach at about the same time as I disconnected the furnace 12 volt line.

I am going to wait a couple of days with the current setup before doing anymore testing. Did I say we full time. We have been "camping" in the coach while I was working on this. Ice chest for frig. Electric heaters for furnace. Stove heated H20 for showers.

So current settings.
Refrig running off postive fused test wire to 12 volt.
Furnace disconnected.
H20 Heater connected via normal wiring.

What next after waiting a couple days to see if everything holds.
1. retest the refrig voltages with the furnace still disconnected.
2. retest the furnace voltages.
3. connect the refrig and h20 heater to normal coach wiring and if successful. let it run for a few days.
4. investigate the furnace wiring and maybe follow the 12 volt wire back to where it connects harness which is also close to where the refrig connects to the harness.

I am suspecting the furnace maybe causing the issue.

I wish I could find a wire diagram of the coach panel board that is above the coach door.

Happy to hear any suggestion good or bad to my testing.

Tom

[tomyoda]

Still working on the issue.

So I have used the test wire from the battery to H20 heater and verified the voltage on the 12V line is the issue. I was able to run the HWH(hotwater heater) using the test wire. I also tested the propane out fault line for the HWH. The red indicator light turns on on the front control panel.
So the crazy thing happened when I reset the the fault light. The voltage dropped on the lines again.

I took the control panel down and am checking the switches that control the HWH electric and gas. I disconnected/reconnect the wire connector in the back of the switch. This reset the voltage and the HWH and furnace are working right now.

I wonder if the switches could be bad.

Where would I find replacement switches that look close to the same.
Black rounded edges, SPST off-on, red light when on and three blades
The red light is on when the switch is on, even if the propane switch/120V is not on to heat the water.

[l1v3fr33ord1]

https://burnstines.com/products/12-v...ch-spst-on-off

[YC1]

This is way more simple than you think.

Of course I have almost 50 years chasing these types of issues.

You have an intermittent voltage "supply issue". The hose (wire), that feeds that common fuse has a bad connection somewhere along the line.

Your strange and a bit varying symptoms are much like trying to use a garden hose to spray off your vehicle. OOPs, you just got a kink in the hose somewhere. You can't see the issue because it is stuck behind a tire.

Just the same, there is a kink in the hose and while you wiggle, tug, and cuss the kink kind of comes and goes. You get some water flow, then full, then nothing.

You know now what needs to be done. You just have to find that darn kink and fix it.

Your substitution is an excellent valid method of diagnosing the problem.

Many people would just keep tugging and poking and swapping parts until they install several more problems themselves.

So far you have avoided any self inflicted wounds. That is great.

Now to chase that darn problem down.

The great advice of running your own ground wire from the battery will make it much easier. Just tape that ground wire to the negative lead of your meter.

At this stage, be sure the fuse for the circuit is in place and your substitute power is not being used.

Take your meter positive lead to a grinder or sharpening stone and get it very sharp. You want to be able to pierce a wire without disturbing it much.

The hard part is tracing back the wire that feeds that fuse. Or perhaps not. I have not seen the fuse panel it is on so can only guess.

You may find some goofy splice made under a booth table for example. You never know where it may be but you must find it.

An inexpensive signal tracer that cost less than 1 hour shop labor will pay for itself. You can get them at Lowes or Amazon of course. Around $35 at lowes. Less on Amazon if you go cheap. Pull the fuse where the voltage goes away and connect the toner. Use the sniffer to chase the wiring. You will light up yourself once you find the problem.