Bad circuits?

[No. 13]

Hello All…it has been awhile since I have posted. This is our 10th year with a 2012 25FCFB and I am happy to report very few issues…until now. Just got back from a quick trip dry camping in Idaho. When we arrived at the campsite both fantastic fans had turned off. Did a quick check of fuses etc. but could not find any issues. Circuit five has two fantastic fans and bathroom fan on same circuit…all with no power. Circuit six which is our furnace was also inoperable.

Electrical is not my strong suit but I do have a 12 V test light. Changed out fuses to be sure and checked both sides with test light and have power at circuit board. In the middle of the night both fans turned on and ran for about two hours. Also had power at thermostat. Morning time everything was dead again. All other components are working fine. Just circuit five and six. When we were getting ready to leave in the morning fans were working again for about 20 minutes. When we got home I plugged into 30 amp shore power in my garage. No luck. Batteries were also at 100%.

I pulled the converter out from under the bed and checked for loose wires etc. Converter was changed out in 2014 to a PD4655 with no issues. Any advice would be greatly appreciate it. I have a multi meter but not really sure what or where to check. Thanks….Gene

[JMynes]

Loose wiring on the negative (ground) buss bar?

Also, check for power when the circuits are inop. If you still have power, but no fans turning, that reinforces the bad ground theory.

[uncle_bob]

Hi

Backing up a bit ....

If the battery is charged then the converter is not the issue. Don't worry about it at this point.

Works / doesn't work / works / doesn't work is pretty much always a loose connection ( or connections ....). It could be in the ground or it could be in the hot wire.

Quick way to check: Go to the device that isn't working. Put your tester on the hot wire to the ground wire. Is there voltage? ( if there is, your device is the issue ...). Now check between the hot wire and the vehicle chassis. Is there voltage? If so, it's a problem with the ground wiring.

Sometimes this is easier to track down with a multimeter. They are pretty cheap these days. It probably will give you a "continuity" (or ohms) function that is helpful for spotting open circuits ....

Bob

[No. 13]

Originally Posted by JMynes

Loose wiring on the negative (ground) buss bar?

Also, check for power when the circuits are inop. If you still have power, but no fans turning, that reinforces the bad ground theory.

Thx…where/what is buss bar?

[No. 13]

Originally Posted by uncle_bob

Hi

Backing up a bit ....

If the battery is charged then the converter is not the issue. Don't worry about it at this point.

Works / doesn't work / works / doesn't work is pretty much always a loose connection ( or connections ....). It could be in the ground or it could be in the hot wire.

Quick way to check: Go to the device that isn't working. Put your tester on the hot wire to the ground wire. Is there voltage? ( if there is, your device is the issue ...). Now check between the hot wire and the vehicle chassis. Is there voltage? If so, it's a problem with the ground wiring.

Sometimes this is easier to track down with a multimeter. They are pretty cheap these days. It probably will give you a "continuity" (or ohms) function that is helpful for spotting open circuits ....

Bob

I have a multi meter just not sure how to use it. Pretty sure my device is not the issue. All three fans go out at the same time and periodically turn back on. How do I check for open circuit. Also the other circuit for furnace is also out. Thx for the reply Bob

[Bill M.]

Did you check the DC fuses? I would start there and at the DC panel. You might remove a fuse and turn on one device and do a continuity check from the fuse panel through the circuit. You will need some long leads for the multimeter and to be clever since you can probably only access the hot side of the circuit there. If it is open you have to narrow down where. Connections to the fuse panel would be suspect. I have no idea how to access those connections. Then it is sorta fixture to fixture to check continuity. Especially since it is 2 circuits. I had one fantastic fan go out from broken wires. I have no idea how the wires broke but the break was inside where the trim ring goes. Both leads looked like they had been cut. Think about any work that has been done on the trailer and where it was. Many of the 12 volt wires in the trailer go around the front fantastic fan so you might take the trim ring down from the inside and look around with a flashlight and wiggling wires.

[No. 13]

Thanks Bill. Will check out what you mentioned. Pretty confident fuses are good. Would a loose wire in one fan affect the entire circuit?

[Bill M.]

I would replace the fuse for that circuit even if it looks good. Easy (relatively) to do and a loose or poor contacting or badly made fuse could cut in and out like that and then finally fail. I do not think a bad device would shut the circuit down but it is not too hard to pull the trim rings and disconnect the fans 1 by 1 to see.

Start with what Uncle Bob said to do. If the circuit is dead replace the fuse. Check again.

[No. 13]

Will do. Thanks

[uncle_bob]

Hi

Multiple devices share a common "feed" wire from the fuse panel. Just where that wire runs varies from trailer to trailer. You start by dropping all the flakey devices and looking at the connections (wire nuts) behind them.

Multiple devices may share a common ground connection. Same basic drill. Start by looking behind the devices.

Rather than getting into the multimeter here. I'd head over to YouTube and spend some time watching "how to" videos there. For basic tool training, it works far better than a forum like this.

Fuses don't always blow in a big black burst of crud. Sometimes the fuse wire barely breaks. Unless you have a pretty good magnifier, it can be tough to visually tell what's what ....

Bob

[No. 13]

Thanks Bob...I did watch a few videos and one in particular led me to the ceiling wire harness connection which is easily accessed. It was just a bad connection where two harnesses are joined...and as always...the last place you check. Good experience though. Thanks again everyone for all the great and quick advice. Gene