Norcold schematics

I’m installing a new refrigerator in my 1990 Hawkins Motor Coach 302. Bought it without one. Is wired for a three way model and that’s what I put in. Norcold NA8LX.3. Physical installation went fine. Plugged in the 120AC and hooked up the 12VDC (which is two 8AWG wires). Started the generator and tried to turn on the frig. It didn’t and the inside light wasn’t on.
Here’s what I discovered. The DC wires to the frig are only 2.0VDC when connected to the frig. It measures fine when the DC wires are disconnected. As soon as I plug them into the quick disconnects the voltage drops to 2. Trouble shooting time. I made a couple of wires and wired the refrigerator right to a battery and it powered up just fine. So there’s something with the existing wiring. I checked the convertor and it’s fine at 12.5VDC, which is my battery voltage and it’s 14VDC with the generator running.
Any ideas, folks? I have no schematics. I checked the 12VDC fuses by the convertor and there isn’t one for the refrigerator. The wiring may be coming off the engine battery, the Norcold manual says to power the 12VDC from the engine battery. I’m going to ring out the wires tomorrow and see if I can trace them back to origin.
Thanks and safe travels.
Edit: Disconnected the engine ground and that secured the DC to the frig. So it is powered from the engine battery somewhere.