No 12v power

[fourthgear]

Good deal , at least you know your wiring is correct .

[OldWEB]

Originally Posted by 901JB

It has 2 heavy gauge reds and 2 heavy gauge blacks and the 2 smaller wires that goes to the circuit breakers

Twice you mention the two smaller wires go to the circuit breakers. Do you mean the two breakers mounted on the side? Then that is wired wrong... please clarify.
Also, there could be two "reverse polarity" fuses in your DC fuse/AC breaker panel that you can check, you said there was no 12VDC in it.

[Gisela]

Originally Posted by 901JB

Just bought a 96 grand manor Thor 3470 I have no 12v power to the the 12v side like the lights when I’m not on shore power or generator running but I have power for the slide out and the power step and the frig out side lights are on , just put 2 new batteries in it last night , any ideas to what I need to check for

On our Motorhome it was the converter, bought a new one, everything works.

[Gisela]

We needed a new converter.

[Wiley1]

Originally Posted by 901JB

Welp my Ol lady figured it out , there was a main switch under the dash on the left of the steering wheel

Man, I don't know how they did things in 1996, but in this millennium, the switch in the cab is normally an emergency battery isolator bypass. In my 2017 Class-C, it would only be closed if you needed to use the house battery bank to help start the vehicle.

Perhaps that secret switch under your dash is some sort of battery cut-out to prevent parasitic draw when the rig is in storage?

I'm still trying to figure out why your two house batteries are not wired in parallel. Are they used for different purposes? Do they have an isolator between them so they can both charge from the same converter?

Going forward, I would not trust any battery cable that you find at Walmart or even an auto parts place. They are just two flimsy. I always order custom-made cables of the exact right length, color, and lug type and specify one or two gauges heavier than needed to reduce overheating and voltage drop.

I have had great success with this place:
https://www.batterycablesusa.com/