Chassis battery disconnect doesn’t work Coach disconnect OK

This Southwind has been a wonderful learning experience.  Our previous 2 motorhomes were very simple, entry level vehicles, with no fancy or automated features at all.  If I wanted to disconnect the battery,  I’d go out with a wrench and remove the cable from the battery post.  🙂

Learning acronyms:  BCC = Battery Control Center.  Its a large black box under the hood.  Its the smarts for a lot of the systems in the Southwind, including the battery disconnects for both the chassis and coach batteries.

The disconnect seemed to be working for the coach,  but not the chassis.  I could hear a CLUNK when I did the coach disconnect / connect.  but the chassis didn’t make any noise and stayed connected.

I didn’t know how the circuits worked,  so digging into the BCC seemed like a good place to start.

REMOVE ALL POWER

I disconnected the coach and chassis batteries and unplugged from shore power. I verified there was no voltage anywhere on the MH.

I then disassembled the BCC, removed the solenoids and tested them, They were both OK. (Interesting how they work. they use a permanent magnet to hold the plunger in)  I took a lot iof photos of the BCC as I disassembled it so I’d be able to tell where the wires went.

There was some corrosion on the circuit board that I cleaned while I had the BCC apart. but this wasn’t my problem.

After reassembly, I got a voltmeter and measured the voltage at the disconnect switches. I had 12 volts on the coach switch (orange wire), but zero on the chassis switch (red wire)

I went to the BCC, measured the voltage there, and I had 12 volts on both wires. HUM….

I started looking around and found the problem by accident. Where the wire bundle goes thought the firewall (behind and to the right of the BCC), there were but splices. In the group of wires I knew came from the BCC, I I could see a red wire was pulled out of the but splice.

I jumped the red wire back to the but splice, and CLUNK – CLUNK the disconnect now works.

I re-soldered the red wire and put heat shrink on it.

When I closed up the BCC, I used a thumb screw and a blind nut plate to replace the bottom missing latch