Please allow me to post the back story in case any of that has anything to do with current issue. Went to hook up trailer for camping trip. Power tounge jack and slide out not working despite being hooked to 120V. Single tongue mounted battery has has 3.5V and 12V system not working without 120V. Soon discover that power jack and slide out needs good battery regardless of 120V available. Install new battery and all is good. At campground they have a power outage for maintenance and the 12V system isn't powering all 12V systems except for power tongue jack and slideout working fine. No 12V lights, radio, or fridge. Battery voltage is still 12.5V All fuses good; 2 30amp. mounted near battery, 2 40 amps behind converter door and several 15 amps....all good. Battery cutoff switch is in ON position. And finally, all 12V systems work perfectly when plugged into tow vehicle. Any info. on possible causes or areas that should be checked are greatly appreciated...Thank You!

With 15 views already and no replies my bet is others are thinking the same as I, that your post makes no sense at all. :h I've read it multiple times and can't make any sense out of what you're trying to say and can only suggest that possibly your converter has failed. To better analyze this you're going to have to be more precise in what works, what doesn't, and under what circumstances.

ronwalt wrote:Please allow me to post the back story in case any of that has anything to do with current issue. Went to hook up trailer for camping trip. Power tounge jack and slide out not working despite being hooked to 120V. Single tongue mounted battery has has 3.5V and 12V system not working without 120V. Soon discover that power jack and slide out needs good battery regardless of 120V available. Install new battery and all is good. At campground they have a power outage for maintenance and the 12V system isn't powering all 12V systems except for power tongue jack and slideout working fine. No 12V lights, radio, or fridge. Battery voltage is still 12.5V All fuses good; 2 30amp. mounted near battery, 2 40 amps behind converter door and several 15 amps....all good. Battery cutoff switch is in ON position. And finally, all 12V systems work perfectly when plugged into tow vehicle. Any info. on possible causes or areas that should be checked are greatly appreciated...Thank You!I'm a little confused :) Early in your post you say battery voltage is 3.5V then later you say it is "still 12.5V". Sounds like the battery isn't hooked up. Or maybe you hooked it up backwards and blew the reverse polarity fuses.Assuming your RV battery was at 3.5V and connected, I would say your converter has failed . When you plugged into the tow vehicle, it brought the voltage up.Sorry to say, it's time to replace the converter.

As Sound guy says...no sense at all.

Look for a circuit breaker or fuse under the front of the trailer. It is normally located at the end of the umbilical cord from TV. You can follow the positive cable from the battery to same location.

From what I read, OP installed a new battery and now getting 12.5. But, still doesn't have any 12 volt inside and campground has no 120 volt due to electrical problem. Do you have received tech service with emergency road service you can call for some over the phone help? I would try flipping the converter breaker all the way off, then put it back to on? Loose grouhd?

12V system not working... | Good Sam Community

30 Replies

BizmarksMom
Explorer
Mar 12, 2018
Look for an in line fuse between the battery and the coach. I'll bet you one of them is blown.
PaulJ2
Explorer
Mar 11, 2018
I would take that battery disconnect switch and turn it on,off,on,off,on a bunch of times and see if it cleans up the contacts and starts working.
wnjj
Explorer II
Mar 11, 2018
Hey ronwalt,

Are you sure you reconnected all of the positive wires to the battery? There may be as many as 4 when you include the jack, slide, breakaway switch and the main lead to the interior.
enblethen
Nomad
Mar 11, 2018
12 volt DC system is working while connected to shore power. That would indicate the reverse polarity fuses are good. Works from TV would indicate wiring is good except for that section between TV connection, battery connection and 12 volt distribution. Only thing between connections would be fuse or circuit breaker under tongue of trailer.
ralph_day
Explorer
Mar 11, 2018
Check those reverse polarity fuses in the converter, sounds like what happened to my b-i-l.
wnjj
Explorer II
Mar 11, 2018
SoundGuy wrote:
The previous posts which come to opposing views as to whether the converter may or may not be faulty are illustrations that the OP's original post is lacking in clarity ... he's offering differing information that just makes no sense at all. I'll say it again - he needs to be more precise about what works, what doesn't, and under what circumstances - until then we're all just guessing at what might or might not be. :S The obvious solution, since he's there with the trailer and we're not, is that he start probing with a DVM to figure out exactly what is and isn't working at it should. If he doesn't have a DVM, get one, if he doesn't have the electrical understanding to solve this himself then take the trailer to someone who does ... after all, that's what tech service is for. Good grief. :R

The only thing that threw me off in the first post initially was the use of present tense for everything. If you read all of it as a chronological story it all makes sense and the information is there. I assume he has a volt meter since he reported some numbers.

Examples of present tense that caused confusion: battery has 3.5V, not had. Install new battery, not installed.

Everything’s still consistent with a battery not connected to anything but the slide and jack. The fact that it wasn’t being charged probably killed the first battery. Now replaced, it’s still not powering the interior or getting charged,
Lynnmor
Explorer
Mar 11, 2018
I have had two of those cheap red key type of battery switch fail in one season. First place to look for such problems. I replaced with a Blu Sea switch.
harley4275
Explorer
Mar 11, 2018
faulty resetable little fuse screwed to the tongue somewhere. it is about 1/2" by 1" with 2 studs and nuts.
JCR-1
Explorer
Mar 11, 2018
Check battery cables and clean solid post connections.. Follow (+) cable for breakage , in line fuse, loose connections or deterioration.Is the battery charging when you are on shore power(converter on fan working). Check for 13.5 volts when on shore power at the battery terminals.
2112
Explorer II
Mar 11, 2018
It comes down to a bad resettable breaker as someone pointed to on the frame or a bad connection somewhere between the battery and converter or ground.
Locate and measure voltage across the breaker. Anything >0.5V measured on the posts, not the ring terminals indicates a bad breaker. Measure from ring terminal to ring terminal. Anything >0.5V indicates bad connection.
Check all connections including all ground connections.