Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×

Go Back   Thor Forums > Thor Tech Forums > Maintenance and Repair
Click Here to Login
Thread Tools Display Modes
Old 08-13-2021, 04:51 PM   #1
terencgb1's Avatar
Brand: Thor Motor Coach
Model: Vegas 24.1
State: California
Posts: 45
THOR #15798
Vegas 24.1 - Should Chassis and House batteries have a common ground?

Vegas 24.1 - Should Chassis and House batteries have a common ground to the chassis ? It does not appear that mine does and this may explain some strange charging / discharging behaviors.

It would seem to me that for the alternator to charge the house batteries there must be a common ground with the alternator / chassis battery? Preferably something that can take the high charging amperages.

As I untangle the mess the previous owner left me with I am finding lots of odd cables, switches to no where and things that were removed but wires left behind. Seems there is a lot of untangling to do and problems to solve and possibly missing a common ground between the two systems might resolve a lot of them.

Any thoughts from the forums would be appreciated.

terencgb1 is offline   Reply With Quote
Old 08-13-2021, 05:04 PM   #2
Axis/Vegas Enthusiast
Brand: Thor Motor Coach
Model: Axis 24.4
State: Michigan
Posts: 9,834
THOR #1150
Yup the whole thing has one common ground.
2022 Thor Axis 24.4
2021 Mach-E
blog -
JamieGeek is offline   Reply With Quote
Old 08-13-2021, 05:14 PM   #3
Senior Member
Brand: Thor Motor Coach
Model: '17-Vegas 24.1
State: California
Posts: 2,098
THOR #13362
With your extra long front window, I suspect that your 24.1 is a 2014-2016 model year.

Over the years changes in the wiring have taken place.

We always suggest that you sign up with Thor and register for info & schematics on your particular coach:
'17 Vegas 24.1
Fallbrook, CA
taylorbob1 is offline   Reply With Quote
Old 08-13-2021, 05:18 PM   #4
Senior Member
Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
Posts: 1,201
THOR #20289
Absolutely yes. You need a common ground for some systems like the BIM to work.

All vehicles have the ground tied to the chassis frame. On my 2021 Axis 24.1 (same coach as yours) there is a single cable coming from the negative terminal of the house batteries that goes to a stud on the frame. Some individual grounds come off of that stud like the cable to the converter. But some like the generator use the frame for their ground connection.

If you are having charging problems and I had them on my new Axis, there might be two sources:

The chassis alternator didn't seem to charge correctly. I investigated and found that Thor routinely wires the Precision Circuits BIM 160 incorrectly. The chassis alternator should be wired to the A terminal. Thor wires it backwards. I corrected it and all of my chassis alternator charging problems went away.

The other may be the WFCO charger part of their converter. Despite their literature saying it is a three step charger, my experience tells me that it is a single fixed voltage output charger, set at about 13.5 volts. This means you get very little charging until the house batteries are well discharged.

I replaced it with a Progressive Dynamics 9260CV and it now charges great.

So definitely rewire the BIM. It is easy to do, just make sure none of the cables touch each other while you do it. The PD charger change out was a little more tedious as it is not a drop in replacement, but I made it work.

DavidEM is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Featured Campgrounds

Reviews provided by


This website is not affiliated with or endorsed by Thor Industries or any of its affiliates. This is an independent, unofficial site.

All times are GMT. The time now is 09:38 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0 PL2