12 volt blues

[Dieselbird01]

Hi Frank,

I’m not sure I’m following what you’re saying but in post #1 you said “Have 120+ volts on both legs of 120 volt panel on both sides of breakers, but nothing works”.

So are you saying that you have 120 volts on the output of every circuit breaker in the Main AC breaker panel while you’re plugged into shore power?

If that’s the case, it sounds like your power cord problem may have taken out the small shore power/inverter power relays inside the coach that automatically switch from inverter to shore power when shore power is being supplied to the coach. Those relays make a fairly loud “click” when they pick up so that could explain the missing click that you mentioned.

Sometimes the coil winding of those relays burn open from a bad neutral connection in the shore power plug or receptacle. With a bad coil, the relays stay in inverter mode.

There are usually at least 1 and more often there are 3 or 4 of those relays inside the coach (my coach has 3 of them under the kitchen sink and 1 on the passenger side inside the chase for my Primus heat). I’m not sure where yours may be but look behind the back wall of the cabinet under the sink for one or more 4x4 metal boxes – may even be marked inverter.

Here’s the part number for those relays:
PRD11AG0-120V

We recently had another WOG member with inverter relay problems so you might want to weed through this post:

https://www.wanderlodgeownersgroup.c...ad.php?t=31597

[frankbarbaraR]

The inverter I installed has a transfer switch, which will pass thru 120 volts when hooked up to 120 volts. I have checked input and output of inverter, all checks as expected. I have face of 120 volt panel off, have checked voltage on both sides of breakers, everything checks ok. Dieselbird1, you may be onto something with the relays, I will try and locate them them tomorrow, how would you check them? Thanks to everyone for the help and ideas!

[Dieselbird01]

Originally Posted by frankbarbaraR

The inverter I installed has a transfer switch, which will pass thru 120 volts when hooked up to 120 volts. I have checked input and output of inverter, all checks as expected. I have face of 120 volt panel off, have checked voltage on both sides of breakers, everything checks ok. Dieselbird1, you may be onto something with the relays, I will try and locate them them tomorrow, how would you check them? Thanks to everyone for the help and ideas!

If you go to the thread that I mentioned earlier, you'll find lots of helpful information about the relays along with a drawing in post #27 that shows how the relays are wired. If the relays have 120 vac hot and neutral shore power getting to them, the contacts should close and send the 120 vac shore power hot and neutral to the load.

[frankbarbaraR]

John, I think you're on target on several notes. I have found 5 relays so far, 3 in a 8x8 box next to a single 4 x 4 box with a single relay in the rear closet opposite wall from 120 panel. The 3 relays are smaller than the PRD-11AGO-120 relay in the single box. The 3 have power to one side on each of them, but no power to the coils. The single PRD relay is working, power in and out.
The outlets in the bedroom have power, 2 reading lights on either side of bed work (I guess the same circuit as outlets). 2 bathroom outlets work, over sink lights work, but florescent lights do not work.
Under/behind sink is one PRD relay, has power and working. One small relay in seperate box, but no power to relay in box. 2 kitchen outlets work, microwave works, outlet on dash works, maybe all on same circuit?
Where should I go from here?
PS for a 65 yr old 6'1" 230 lb man getting in the rear closet is a pain in the #$%@!

[Dieselbird01]

Originally Posted by frankbarbaraR

John, I think you're on target on several notes. I have found 5 relays so far, 3 in a 8x8 box next to a single 4 x 4 box with a single relay in the rear closet opposite wall from 120 panel. The 3 relays are smaller than the PRD-11AGO-120 relay in the single box. The 3 have power to one side on each of them, but no power to the coils. The single PRD relay is working, power in and out.
The outlets in the bedroom have power, 2 reading lights on either side of bed work (I guess the same circuit as outlets). 2 bathroom outlets work, over sink lights work, but florescent lights do not work.
Under/behind sink is one PRD relay, has power and working. One small relay in seperate box, but no power to relay in box. 2 kitchen outlets work, microwave works, outlet on dash works, maybe all on same circuit?
Where should I go from here?
PS for a 65 yr old 6'1" 230 lb man getting in the rear closet is a pain in the #$%@!

Not sure without seeing them but those smaller relays may just be the relays that supply 120 vac to your air conditioners. If so, the "coils" of those relays are 12 volts DC - not 120 volts ac. A fuse supplies 12 volts to the air conditioner relay coils and the switches at the dash supply the grounds for the coils.

You should add what kind of a coach you have to your signature so that we know what we're working on and maybe make a list of everything that's working and a list of everything that's not working and post it here to see if someone with a similar coach can point you to the relay location for what's not working.

[frankbarbaraR]

Sorry for the confusion, John. My computer literacy (or lack thereof) is showing. Bus is 1990 WBWL PT-40, side bath. Did more checking, looks like plugs work, only lights working are upper incandesent lights in bath and bedroom. Microwave works, fridge does not. Air conditioners do not work. Master eletronic switches are on, ac switches on dash are on, all breakers in 120 volt panel are on except heated holding tanks, block heaters, etc. Any help greatly appreciated!

[frankbarbaraR]

It's been a few days, here's where we are now. After speaking with John and others (thanks to all), the problem was narrowed down to the converter/charger leg of the 12 volt side of things. Between the chargers and the shunts were 2 things with problems, the first was a quick connect (purpose unknown), the second was a solenoid switch for charging the generator battery. Had disconnected and cleaned contacts, but still did not make good connection. Installed new cables to solenoid, still no power. Switched cable around solenoid, SUCCESS!!!! Solenoid maybe stuck, maybe this was the clicking I heard in the past Will try to disassemble and repair, may or may not replace. Anyway, have power, everything's lovely! Thanks to everyone for the ideas and help, this forum is awesome!

[NoGas]

Originally Posted by frankbarbaraR

Recently had problem with 50 amp cord and receptacle make/break connection. Wire on bus side of receptacle became loose after 25+ years! Removed receptacle and fixed problem... Any thoughts on locating the problem? Thanks for all the help the forum has been through the 5+ years we have owned the bus!

I see you fixed it. Congrats! Here’s some good general advice I have repeatedly learned the hard way...

When something quits working after I’ve made a change or “fixed” something, 99% of the time I CAUSED IT! However, sometimes it’s hard to see the forest for the trees. When an issue crops up after I’ve made a change or upgrade, to solve the new “problem” I start by going back to the beginning. What exactly was wrong when I started and how did I “fix the problem”? Was everything working correctly before my fix? Am I 100% confident my “fix” was correct? I then go back and triple check that fix. If it looks perfect and it still doesn’t work, I try putting it back the way it was when everything else operated correctly! If things start working again then I know where to begin. If they don’t then I start praying that I didn’t cause irreparable damage. Fixing something from that known starting point is always best...

Several years ago I had an intermittent short in the shore power cord between a hot leg and N that cause all kinds of weird symptoms (similar to what you described). The way I discovered it was to do continuity checks for each of the shore cable lines between the plug end and where they connected in the ATS.

[frankbarbaraR]

Thanks for the comments. One project for this winter (it will be 100 dg later this week) will be to install shore cord reel with slip ring, replacing current cord arrangement. Have inline surge protector in box to install, move transfer switch from rear closet (what a pain in the @#$!). All move to bay on road side of bus.