Battery Isolator Terminals

Here is another maintenance item for you.

Last week I was poking around under the hood when I noticed a lot of corrosion on the battery isolator terminals. Grabbing onto the wires, I could move them around. The nuts appeared to be tight and the studs themselves were moving. Using a multimeter I checked and found a small amount of voltage drop over two of the terminals, indicating a poor connection. I removed the screws holding the radiator reservoir in place and tied it back to provide access to the isolator's terminals. After disconnecting all power, the starting battery, coach battery, converter and solar panel, I removed the three nuts on the isolator and pulled the wires terminals off. At the base of each isolator stud, there is a thin nut. I snugged each of them up without over tightening since I did not want to break off anything inside the isolator.

The wire terminals were cleaned with a stainless steel brush and then everything received a coating of dielectric grease before reassembly. Checking afterwards, I found no voltage drop.

http://www.flickr.com/photos/lwade/sets/72157616714752420/

Contributor: Larry Wade

The Hidden 12V Breaker

Where is the 12v reset switch hidden? It depends on the floor plan. It's always within 18 inches of the chassis batteries.

Late Model Mid Bath

The breaker is located on the cabinet structural member that divides the refrigerator stack from the stove.  It's rather difficult to access.  

In the first photo showing the open cabinet under the fridge, the circuit breaker is to the left when looking in.  A side panel must first be removed (attached with four screws).  Note that in the photo, the back panel is removed, exposing the plastic battery compartment housing.

The second photo shows the bottom of the cabinet structural member that separates the refrigerator from the stove.  The white mass to the right is the freshwater tank.

The third photo is a close-up of the circuit breaker.  The reset button is barely visible on the left side.

Here's a photo with the drawer out.  It's now obvious to me that that's the intended way to access the breaker.  The breaker is bottom left in the photo.

Jim

1983 Mid Bath

Located under the dinette seat

2010 Rear Bath

The reset breaker is under the dinette seat! 

Removing the cushion to the forward most seat,  I realized that 1/2 of the storage under that seat is covered with a piece of plywood.  And, it is screwed down. 

Most would say, "why would you put a reset device under a panel that requires you to unscrew it - to view it".

After removing the four (4) small screws, the hole contains a sealed battery box for the house batteries, a junction box for wiring, the secret 12V reset breaker, and a good look at one end of the house freshwater tank.

So here are the photos for those of you looking for this secret Reset Breaker on a 2010 Rear Bath.

Cheers!

Tony R. (aka codefour)

2021 Rear Bath

In our 2021 RB the breaker is now mounted on the left side rear wall of the battery box. There are no breakers outside of the box.

Mike C

2007 Twin King

Here are pictures of the 12V circuit breaker/reset switch in our 2007 TK. It is under the refrigerator on the wall to the left. It can be seen after the large drawer is pulled out from under the refrigerator. The back of the battery box is on the left, the power center is below, and the water heater is on the right.

Charles

Rear Kitchen

It is located behind the drawer directly below wardrobe - next to the couch.

Rick

30/31 Foot

The photos are from 2002 30' with the 2 drawers under the fridge pulled out. The breaker is on the floor in the lower right hand corner while facing the fridge.

Chris

26 Island Bed

Probably the most difficult to access since the power distribution box has to be removed.

MattB

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In addition to the hidden 12v reset switch, there is another 12v system breaker in the battery compartment.

The first schematic is from a 2004 and before owner's manual. The presence of a diode isolator on the firewall indicates it's applicability. Notice the "hidden" breaker on the right, feeding the power distribution box. On the left is another breaker that is mounted in the battery box.

Starting in 2005 a solenoid exciter was used in lieu of a diode isolator. The function is the same. 

The black 100-amp breaker in the battery compartment protects the circuit between the battery isolator or relay and the coach battery.

The "hidden" circuit breaker protects the power supply to the 12-volt side of the Power Center. It trips when it gets hot, as in a short.

Some LDs come with an automatic breaker, they reset themselves and do not have buttons. Our 2003 came with an automatic breaker.

Larry W

This breaker is the automatic reset type, normally requires no manual intervention. The only time it needs attention is a serious short circuit occurred, forcing it to constantly trigger. In that case, a detailed troubleshooting is needed to find where is the short in the 12v circuits.

GM Diesel Engine

These 6.2L GM diesels use 12v starting systems. The starting wiring system is the same as a gas powered chevy except they have two engine batteries, one under the hood driver's side and another under the vehicle below the driver's seat.

Problem: Won't Start

If the starter and batteries tested ok, then it's battery cable connection problems or the starting circuit that comes from the ignition switch through the neutral safety switch down to the starter. First try cleaning your battery connections. Especially at the battery under the hood were the cables from both batteries connect. Check voltage at the purple wire on the starter while trying to start the engine. Then check the voltage on the battery cable at the starter while cranking. They both should read close to battery voltage. The blue finned box under the hood is a battery isolator that isolates the house batteries from the engine batteries from the charging system and isn't part of the starting system.

Contributors: Billy J. Brower

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