Dead Short

[ruffis]

Hello all. I recently had my auto transfer switch replaced. Shortly after on the drive home the GPS froze up, radio and back-up camera are fine tho. A clue? Parked our 2010 Greyhawk 31 FK but 2 days later the chassis battery is dead. Used house battery switch to start and drive to my mechanic. There’s a 20 amp draw at the chassis fuse panel #62 labelled “modified vehicle”. Shop manual says there is nothing suppose to be hooked up to this circuit but when fuse pulled we loose the power/heated mirrors. So I have fit an on/off switch into chassis - cable to buy time. 

Do I buy a clamp meter, connect it to the - or + battery cable? Hope to see this 20 amp draw then disconnect in/out leads on the new transfer switch. (RV not plugged in, genset off but single house battery still connected. safe to proceed?) Draw still there? Kill coach 120V breakers one by one. No change? Pull house 12V fuses one at a time and so on. If no change proceed to the chassis fuse box and repeat. 

 My knowledge on all things RV electrical comes from these forums and the research they inspire. Translation  - I know enough to be dangerous right? Cautious by nature, am I on the right track here? At a shop rate of $120/hr I gotta try and fix this problem myself. The field RV tech who replaced our smoking (seriously) auto transfer switch is done for the season and doesn’t answer my voicemail/emails. I’m fearful the campground post supplied power might have caused all this from the get go. They had it checked when I phoned them about my situation for what that’s worth. 

So that’s it. Any advise is greatly appreciated, hope yer having a much better RV experience than me!, LOL. Enjoy this day!

 

 

       

[wolfe10]

ruffis,

Welcome to the FMCA Forum.

I am confused by the mixing of discussing battery draw with 120 VAC.

I assume the 20 amp draw was on your 12 VDC system. So, chassis battery or house battery?

I would start to isolate that draw  (which is HUGE, BTW) by asking Jayco for an electrical diagram to determine what is on that circuit. With 20 amps, my first guess would be mirror heaters if you have them.

Again, the GPS is 12 VDC (I assume), so can't see any relationship between the 120 VAC ATS and the 12 VDC powered GPS.

Please keep us posted on what you find.

[ruffis]

Thank you for the quick reply wolf, to clarify the draw is on the chassis battery as diagnosed at an auto/RV repair shop.  They traced this 20A draw to Fuse #68 in the power distribution box located under the hood, not the passenger compartments fuse panel. This panel contains the high current fuses. They said this should be an unused circuit, their shop manual (F- 450 chassis) indicates “ 50A Modified Vehicle”. Their hunch is something on the coach side has been connected to this. So I pulled this fuse myself, tried all chassis switches and curiously enough I lost the power/heated mirrors function, (quite the hunch on your part!). Please note also their is NO fuse labelled “mirrors” in this power distribution box. There is a 5A fuse labeled “mirrors” in the passenger fuse panel according to the owners manual. I haven’t found this fuse box yet.Should I pull this fuse again and see if the battery stops draining? All I’ve got is a volt meter, do I need to buy a clamp style DC Amp meter to confirm “0” Amps at the chassis battery?

 I thought I should mention the auto transfer switch replacement because that is the only electrical work performed on this unit. Everything has been working perfectly till that drive home when the GPS portion of the in dash radio suddenly froze, it’s still showing the map that was up at that moment. The only other change is the over cab TV, it was always “on” (Power LED illuminated) whether the Xantrex Inverter was on or off. I just used the battery disconnect switch to deal with this. 

Now it has NO power running to it, unit plugged in, genset running, MH idling or Inverter on. Haven’t tried just plugging it in with an extension cord from the house, I’ll try that right now. I bought this unit in July this year so still getting to know how everything functions.

[richard5933]

Just a guess, but it sounds like the switch to your heated mirrors failed, or the wiring to the switch has a short in it. If you can get to the back side of the mirror heat switch, take a look and see what's going on there. You might find that switch has fused itself in the 'on' position, or that something is shorting against the terminals on the back of it.

Possibly the items which went wonky are on the same circuit, but the items which remained functioning (camera and radio) are on the house batteries and not the chassis batteries.

[ruffis]

Great idea, the mirrors are metal framed but must be accessible. I will take a look ASAP, thanks

[ruffis]

Checked those mirrors, the glass portion unclips from the inner frame by the way. This allows you access to the wiring, heater element etc. Everything looks fine, connections good, no kinks, frays etc. Back to the drawing board...

[richard5933]

Did you check the switch(es) that turn the heating element on & off?

There might also be a relay in the circuit which is triggered by the switch.

Switches and relays can fail, and sometimes they fail in the 'on' position.

[manholt]

ruffis,, welcome back...you have had 9 years of reading this Forum! 

Did they put a Sea/Land toilet in?  20 amp fuse runs it and my last 2 coaches has the S&L..last coach was a Tiffin and it was wired to the start batteries by mistake!?!  If you don't, then I think that Richard is on the right track!  

I would also check the new ATS, make sure there is no loose connections, not every shop use a torque driver!

[dickandlois]

Ruffis, Welcome to the Forum !

       There’s a 20 amp draw at the chassis fuse panel #62 labelled “modified vehicle”. Shop manual says there is nothing suppose to be hooked up to this circuit but when fuse pulled we loose the power/heated mirrors. So I have fit an on/off switch into chassis - cable to buy time. 

The Circuit you referred to is often referred to as a Coach builders circuit. So a chassis mechanics information would not have any info on what is connected.

The items mentioned and the items you mentioned are frequently connected to this type of circuit powered by the chassis batteries.

The Chassis builder should be able to supply you some PDF files that contain the circuit drawings for you coach. 

        The only other change is the over cab TV, it was always “on” (Power LED illuminated) whether the Xantrex Inverter was on or off. I just used the battery disconnect switch to deal with this. 

There are 2 battery disconnect switches, one for the chassis and one for the coach 12 volt systems. The Inverter will not be turned off by the disconnect switches. That function is part of the Xantrex remote control panel.

    Rich.