I think most everything stock is grounded to the Body, even the original battery connections, black ground from the battery has two lines.. one goes to the engine and the other the body.. but not so sure about it going to the Frame.
In my case, I had a "lucky" short that started from the bumper to the frame and tried to find it's way to the body back to the battery. I got lucky since it took an easy path from the frame to the steering lines touching the brake lines just below master cylinder..
Lucky, because it was cooking from the arcing but I caught it in time! The coiled brake lines "glowed"!!
Long story short it was the faulty winch that was shorting to the frame..proved it with another known good winch; the wiring was good.
But that got me thinking after that since we noticed that the ohm's reading were not the same from a location to the frame versus to the body..
We at least added a ground wire from the second battery to the "same" ground as the first battery versus finding a nearest body ground. We also added insulation to isolate where it was arcing..
I'm not an electrical guru but I guess the best way to find out is with a ohm meter and measure your ohm resistance comparing to body and then comparing to frame.. they should be the same from the same point..
Now to notch it up.. Which ground would you ground the "House Battery"? The body or the frame?
I think the answer should be both..making sure there is a good ground between the body and the frame in the first place..
I'll be trying to find out how it done from the factory, if not, I'm adding one..
96 RB E-350 460v8 4x4 Custom RestoMod
Warn12kWinch,FFloater,LSlip,Pwtrx Locker 4.10 305x70x16 ToyoMTs,Eagle Alloys,Stove,4CF Ppane Fridge, Air CompTank,Supersprings, Bilstein Shocks,Deavers,CastIron Diff Case, Bullet Proof ReBuilt Transmission, Tubulator DeRale Trans Pan Cover, SSExhaust, KyoceraSolar, Tripplite UPS, 8D AGM, TivoHD, 24in HDLED
95 FJ80 ARB/Kaymar/Emu
2005 AMG CL65 691hp 875tq