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Schematics are not available to the public, even us techs can’t get them. An OHM meter, jumper cables or tone generators can be helpful, but wiring is in bundles so it may give false readings. I usually end up taking the underbelly off enough to access what I’m working on.
If it’s riveted, grind off the rivets, and use self tapping stainless screws with washers to put it back.
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.