no 12volt in coach-only when plugged into tow vehicle

[Lynn608]

Hi all.. hope everyone is safe from Irma. Here is my sad story..

While running from Irma we pulled into a Walmart parking lot to sleep for an hour. Went into our 2016 Forest River MicroLite 25KS travel trailer. No 12 volt power at all.. even tho the battery was up. Jack and jack light worked fine.
Plugged trailer back into tow truck and bingo.. all good 12 volt even fridge. We arrived at camp and plugged into 110 and all was good.. 12 volt system worked fine.

After thinking about it I asked dear hubby to check the converter (bad idea) he flipped the breaker switch to the converter and the whole 12volt system went off and would not come back on. Went and bought a new breaker switch just in case but nothing changed.
We spent the rest of the week plugged into the truck so we could keep the fridge cold and used the main 110 power for all else so as not to drain the truck battery.
So.. what do you think. Why did the battery not run the 12volt system when the truck pigtail would.. and .. we've checked the battery, connections, ground etc and all good. Have we now also killed the converter or is there a reset or something?

Look forward to hearing your thoughts...
Thanks
Lynn

[Lynn608]

Hi all.. just in case someone else has the same issues.. it was the converter..
Got the RV tech people out and fixed it all in 45 minutes.
Thanks for all the input from the forum.
Lynn

[John_Wayne]

The jack motor and light is connected directly to the battery. Is the battery hooked up backwards (pos to Neg post??) Are all the fuses inside the trailer at the circuit board good. Inside you should have fuses and breakers. Fused for 12 volt breakers for 120 volt.
you mention the converter went dead is that fixed (working?) Should be 2 fuses on the converter to protect against having the battery hooked up backwards.

[Lynn608]

It must be that the jack and the jack light are not connected to the interier 12volt system...

[Lynn608]

Yes Red 31 you are right... thanks...

Joebedford when we are not connected to the truck and not on mains power nothing works.. nada.. no fridge no lights.

When we connect to the truck all the 12 volt stuff works. When we are on mains power none of the 12 volt stuff works unless we hitch up to the truck to run the fridge which is 12volt.
The jack works and the jack light works on it's own. Whether in coach power is on or off.

[joebedford]

Just curious - what do you mean when you say the "12 volt system isn't working"?

You say the fridge is working, the jacks are working, at least one light is working. What isn't working?

[red31]

Lynn608 wrote:
Well, the converter must be running if the lights etc are on while connected to the truck right?

No, the converter converts 120v to 12v when on utilty power. On batt/truck the converter is off.

[Lynn608]

Thanks Captain Happy and wnjj.. We've checked the batter disconnect switch.. no problem there. The 12volt system does run with the truck connected.. it won't run when only on the 110. Well, the converter must be running if the lights etc are on while connected to the truck right? We are going over later to check all the great suggestions here.. I'll let everyone know the outcome for other poor souls in the same boat. Thanks all.
Lynn

[wnjj]

X2 on looking for a battery disconnect. Also try powering up the converter with the truck connected. The converter may not stay running if there is no battery that it can "see".

[Captain_Happy]

If your jacks work, I don't buying another battery is going to fix your problem. You need to get an volt-Ohm Meter, and learn how to use it. Another question, does your rig have a battery disconnect switch located somewhere that's turned off?

[westend]

Lynn608 wrote:
Thank you very much... there is a metal junction box which Dear Hubby will go into when his vertigo wears off from going under the A-Frame today.. We've determined the battery is good as the jack and the jack light work just fine.. we will try another battery tomorrow tho just in case. Will also check fuse box but I think we determined the fuses were all good.
Thanks again.
Lynn

You owe it to yourself to buy a 12V test light and/or a hand-held meter. The meter is usually better choice as you can measure voltage/resistance. The learning curve is very mild for learning how to use a meter.

Without either tool, tracing the path of electricity and it's presence is problematic. If you have a loose 12V bulb and some wire, you can fabricate your own test light but they are under $5 at most stores.

[SoundGuy]

Lynn608 wrote:
... there is a metal junction box which Dear Hubby will go into when his vertigo wears off from going under the A-Frame today..

Most circuit breakers used on recreational trailers are thermal, auto resetting - like this ...



Only a few $ ... 30 amp will do for most trailers, 'though if the original is stamped with a rating just replace it with another of the same.

[Lynn608]

Thank you very much... there is a metal junction box which Dear Hubby will go into when his vertigo wears off from going under the A-Frame today.. We've determined the battery is good as the jack and the jack light work just fine.. we will try another battery tomorrow tho just in case. Will also check fuse box but I think we determined the fuses were all good.
Thanks again.
Lynn

[westend]

Follow the positive battery cable back, from the battery. There should be that circuit breaker within a few feet. Yes, it's sometimes in a junction box, tucked inside the frame. If it has a button, it's a manual reset breaker. If it is just a metal can, it is self-resetting. Replacements are available at auto parts stores.

How are you determining your battery is good and charged fully? Do you have a hand-held meter?

If your converter is not outputting charge current, it may have a fuse blown. Check the 12V fuse panel or on the converter, itself. These fuses will typically be higher amperage--40, 30, or 20 amp fuses. Again, available at auto parts stores.

[Lynn608]

Thanks Ivylog..