Forum Discussion

slow96z's avatar
slow96z
Explorer
Apr 25, 2017

Aux Battery Switch Trouble

Hi all:

I have a new to me 2005 Damon Challenger (Ford chassis, gas class A)that has an issue with the aux battery circuit. When I push the momentary switch on the dash I would expect the voltage between the chassis battery (running, showing 14.4v) and the house battery to equalize, but what is happening is the house battery voltage (12.50) starts top climb very slowly, as if it were connected to a charger instead of being parallel connected to a higher voltage source.

There are 2 solenoids under the hood, one black and one silver. I believe that the black one is the house battery disconnect solenoid and the silver is the aux battery connection solenoid. The fuse on top of the black one is good and I don't think that would matter anyway. I found a 7.5 amp fuse in the fuse panel next to the solenoids blown, but replacing it did not resolve the issue. There is a 30 amp fuse that connects to a brown wire that I believe feeds the panel, and that fuse is good with 12v to the circuit.

There is a green/red wire in the same terminal as the brown wire and it has a butt connector on it but it doesn't look like it has ever been crimped to anything so I'm thinking it's for a circuit I don't have.

Does anybody have any ideas why I would only get a trickle of voltage across the solenoid when the button is engaged? And is this green/red wire supposed to be connected to something?

There seem to be a few electrical gremlins in this coach, but this one is the one I'm most concerned about since it left me unable to run my generator yesterday due to a dead house battery from leaving the water pump on while away...

Thanks in advance!

Justin
  • CT_WANDERER's avatar
    CT_WANDERER
    Explorer
    Apr 26, 2017
    See what the voltage is on each side of the flat bar terminals. without the engine running and then with the engine running and the Aux switch on.
  • enblethen's avatar
    enblethen
    Nomad
    Apr 25, 2017
    In the center photo, check continuity of the coil. Disconnect one wire. Check to make sure there is good 12 volts to the coil.
    Isee corrocion on the terminal bolts. Make sure it is clean for good continuity.
    Two small terminals should get 12 volts from charge circuit and from the aux start button.
    Trace the wires back to see where they are fed from if 12 volts is not present.
  • slow96z's avatar
    slow96z
    Explorer
    Apr 25, 2017
    MrWizard wrote:
    Did you check house voltage before doing this
    Did you put a CLAMP ON DC amp meter around the cable and see how many amps is going to house batteries when doing this
    Remember is normal to have many more house batteries than chassis batteries, and no you are not going to see 6 batteries jump up and show equal voltage

    The way it sounds the house batteries are low
    And the alternator and chassis batteries ARE a charging source
    You are not going to see instantaneous 14.5v unless the source does not drop voyage from the amps load going to the Now Connected house batteries

    If you measure low amps going to the house batteries, start looking for a bad connection a aka circuit problem or relay problem

    The batteries should be already charging when you start the engine
    If not then have a charging circuit problem


    Wiz:

    I don't have my amp clamp here, it's at work. I'll bring it home tomorrow and see what the charging amperage across the house battery cable is when the engine is running. Right now there is only one house battery. I have looked at all of the connections that I can see, they are all clean and tight with a chemical coating on them to prevent corrosion. I know that the solenoid may have internal corrosion, but externally the connections are corrosion free.

    Thanks,
    -j
  • slow96z's avatar
    slow96z
    Explorer
    Apr 25, 2017
    Chris Bryant wrote:
    Keep in mind, the emergency start solenoid gets its power from the house battery, but if they used the same relay for charging, you should not need to hold down that switch.
    Either there is another solenoid, that solenoid is bad, or you have more problems.

    Can you post a picture?


    Chris:

    I was able to jump start the generator by putting a jump box on the house battery and then the generator charged it after a couple of hours driving - there is enough charge in it now to activate the switch, as the house battery connection at the solenoid (solenoid to house battery - 4ga) shows 12.5 with the switch not pressed.

    Here are some pictures:

    The solenoids:



    The brown and green/red wires:



    The loose green.red wire end:

  • enblethen's avatar
    enblethen
    Nomad
    Apr 25, 2017
    Sounds like it could be back-feeding the power to the coil of the silver relay.
    With the engine off, push the auxilary start switch. You should hear a good solid click from the silver relay.
  • MrWizard's avatar
    MrWizard
    Moderator
    Apr 25, 2017
    Did you check house voltage before doing this
    Did you put a CLAMP ON DC amp meter around the cable and see how many amps is going to house batteries when doing this
    Remember is normal to have many more house batteries than chassis batteries, and no you are not going to see 6 batteries jump up and show equal voltage

    The way it sounds the house batteries are low
    And the alternator and chassis batteries ARE a charging source
    You are not going to see instantaneous 14.5v unless the source does not drop voyage from the amps load going to the Now Connected house batteries

    If you measure low amps going to the house batteries, start looking for a bad connection a aka circuit problem or relay problem

    The batteries should be already charging when you start the engine
    If not then have a charging circuit problem
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Apr 25, 2017
    Keep in mind, the emergency start solenoid gets its power from the house battery, but if they used the same relay for charging, you should not need to hold down that switch.
    Either there is another solenoid, that solenoid is bad, or you have more problems.

    Can you post a picture?
  • slow96z's avatar
    slow96z
    Explorer
    Apr 25, 2017
    janechucknicodemus wrote:
    I would be looking at any and all grounds. The weakest places for power leaks. Once you have made sure,,( by disconnecting cleaning and replacing tightly) then get a good charge "one battery at a time" and try all over. This may just help you a bit.And the GREEN wire is usually a ground!! RED IS POWER! HOT.
    IF IN DOUBT read the book?
    Good luck Justin

    Chuck


    Thanks Chuck. I should have been more clear, the green/red wire is green with a red trace and is in the same harness terminal on the board as the brown fused wire so I'm sure it's supposed to be V+.

    Do you have a link to the wiring diagram for this coach? I can't seem to find one.
  • slow96z's avatar
    slow96z
    Explorer
    Apr 25, 2017
    the voltages I posted were with the engine running. The house battery was at 12.50 and while holding the switch slowly came up - about .01V every 10 seconds, but definitely climbing. It went back down when I released the switch.

    Is the battery control panel the one under the hood next to the solenoids? That would make sense, but no fuses in that panel are bad anymore.

    Sure would be easier to test with a helper pushing while I meter it out.
  • janechucknicode's avatar
    janechucknicode
    Explorer
    Apr 25, 2017
    I would be looking at any and all grounds. The weakest places for power leaks. Once you have made sure,,( by disconnecting cleaning and replacing tightly) then get a good charge "one battery at a time" and try all over. This may just help you a bit.And the GREEN wire is usually a ground!! RED IS POWER! HOT.
    IF IN DOUBT read the book?
    Good luck Justin

    Chuck

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,189 PostsLatest Activity: Jan 21, 2025