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No 12v Power in Coach
Well, I had my 50DN removed, rebuilt and reinstalled today in Reno, NV.
The trouble began during the install when they could not get 12v power from the key switch. They swore they rewired everything exactly the same as they found it. Their solution was to run a wire from a key switch controlled power stud in the rear panel over the engine to the key switch input on the voltage regulator. This allowed the alternator and voltage regulator to work.
When I arrived at the RV park an hour later, I discovered I had no 12v power anywhere in the coach. I could start the coach and the dash worked, but that was it.
The toilet will not flush , no lights inside, the hvac thermostat will not work so no air conditioning, none of my Sunmullon switches will work, no 50 amp cord reel, no power to the generator slide, cannot start the generator from inside, cannot turn on the electric water heaters… No 12v power
I cannot find any tripped breakers. I cannot find any blown fuses. I did notice that the ECC cabinet fuses on the bottom row show no green lights under them. The left half of the cards in the ECC cabinet seem to be dead. No red or green lights are visible on these cards.
I am going to check the input voltages on the top of the ECC cabinet in the morning and swing the motherboard open and investigate it further.
Any ideas guys ? I am stumped.
Michael
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13 Replies
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Apples and Oranges Michael.
You are describing power lost to the house, yet it is OK at the chassis. At least that is what it sounds like.
Verify all bus electrical systems are normal. Then If my guess is correct you either have an isolator that supplies power from the 50DN to both the house and chassis (probably not) or you have the 50DN as the house system alternator and a separate 24V alternator dedicated to the chassis.
What that means is if my second option is correct the 50DN is not charging or there is an open circuit between it and the house batteries.
There are a lot of questions I could ask, but first have to understand how your coach is set up.
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check isolator for house side
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As I said last night on the phone the 50 DN is for the hose only and should not have effected the 12 volt power to the coach.
The only thing I can think may have happened is they shorted one of the house battery cables when they were re attaching to the back of the 50 DN.
Those two battery cables go directly to the black box in the battery bay between the two inverters.
There are a couple of solenoids in there that relay power, check and see if you have 12 volt to either side of the relay.
The 12 volt power cable on the top left side of the ECC cabinet should have 12 volts. I don’t remember where that cable is going to but I think it is from the relay in the black cabinet in the battery bay.
Check all the fuses along the bottom of the ECC cabinet, one of the larger fuses should pass power to the mother board.
I can’t come up with a reason you don’t have ignition power, the 50 DN work should not have affected the coach chassis power at all.
Also look in the gray elecctrical panel above the engine, there is a solenoid there That is and ignition key source.
Also check the 12 and 24 volt lugs in the upper cabinet above the steer compartment.
Also look at the number #34 wire in that location, I think this is your ignition wire to the key switch.
Just a thought but check the voltages at your Vanner equalizer ad see if you have 12 and 24 volt, this will not affect the house but does proved service to the chassis.
If I come up with any other ideas I will call you.
Two guys that would know for sure is Gill Johnson or Miles Circo.
I don’t have their numbers any more but I think you can find them on POG.
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If the coach will start there is 12V at the chassis side. The ECM needs 12V. If any doubt, turn on the lights. They are 12V.
Look for the issue starting at the 50DN.
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Did you check the battery disconnect by the front door, and it should have a solenoid from switch that might have failed that disconnects the house.
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If you have a 12v master disconnect switch? it may be turned off. My Liberty has a 12v master cutoff/disconnect switch in a bay. If its off my bus loses all the stuff your talking about.
If there is a battery isolator downstream from the 50DN? it may have failed and isn’t allowing the low house batteries to be charged by the newly rebuilt alternator. -
Thank you for the suggestions guys.
The lugs in the upper cabinet above the steer compartment shows 12.8v.
The lugs on the top left side of the ECC cabinet shows 00v.
I will check the relay in the black cabinet in the top of the battery bay next.
Thank you Jon, but as Buddy points out our Country Coach’s have completely separate house and chassis systems. However, the house 50DN regulator does need to see 12v from the key switch to turn on.
Thank you Art, but I do not have a battery disconnect by my front door.
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Michael, I understand the key has to be on to excite the field and it can come from any key on 12V source. The question is if you are getting 12V to the field wire with the key on. What you describe is like I would expect from a completely open circuit on the house battery side.
A bigger question is if the coach had everything working when the 50DN was changed, why aren’t the guys that replaced it fixing it. I mean how bad can someone screw up four bolts, a drive belt and a cable and 2 or 3 wires to the 50DN.
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On the chassis side Michael, make sure the rear toggle switch for rear start is in the right position. Work it a few times, they’re trouble.
You must have a house disconnect somewhere and I assume it’s in the right position.
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Ok, problem solved. Thanks guys.
Buddy, Art, Jon and Tom had the winning suggestion, it was a 12v disconnect switch. It was just in a different location.
Thank you all for your help.
Jon, you are right about how hard is it to connect a few wires. That is all these guys know. They were very confused when they had no 12v from the key switch wire. It was there before they took the alternator off and it wasn’t there when they put it back on. I think they tripped the 12v house circuit when they disconnected the house batteries, load tested them and then reconnected them.
Again, Thank you all for your help.
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It is great to hear a good outcome.
The message here is to keep incompetent people from working on a coach. Except for the weight of a 50DN there is nothing difficult about replacing one.
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I was doing some rewiring on my house battery bank yesterday (I will share with you why shortly). When I finished there was no 12vdc power in the coach. Turns out on mine the battery shut off solenoid turns off when the master ground is removed. Remembering this thread pointed me in the right direction.
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I helped a friend out yesterday, he rents RV’s and sells them too, He’s got a 2007 JaycoSeneca that he sold and new owner was there to pick it up and the generatorwould not run, he said it ran a couple of days ago, So I ask any work has been done lately and he said new house batteries were installed. Traced it down to a black cable coming from gen was a positive cable connected to negative no juice, So the guy he hired to install new batteries was not paying attention, so I wrapped red tape on black cable, you just never know?
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