Second Generation Models
The Norcold second generation of electronic refrigerators modernized the older 838s and 8310s. The switches and wiring in the eyebrow were replaced with a circuit board, which also incorporated the electronics necessary to use a thermistor as a temperature sensor. This eliminated the mechanical thermostat. There were several models in this generation that eventually transitioned into the 600 series models. A three way version (AC, DC, gas) of the last configuration of this generation is shown in the graphic below. It would be the 663 or 683, with the On/Off Humidity switch on the eyebrow. Earlier versions had the switch located between the freezer and refrigerator doors. Some of the older models in the transition are not well represented in the graphic. All of the second generation models require 12 volt (for the circuit board) to operate on any heat source.
Another generality with these models that have eyebrow controls is how to isolate a problem between the eyebrow board, Power Supply Board, and the modular cable that goes between the two boards. If there is 12 volt to the eyebrow board and the appropriate light doesn't work, the eyebrow board is the problem. If there is no 12 volt to the eyebrow board, the cable or Power Supply Board is bad. Check connections at both ends of the cable and, if good, change the Power Supply Board. If the lights work on the eyebrow board but the Power Supply Board is not putting out the proper output (i.e. 120 volt to the 120 volt element), then the problem is the cable between the two boards or the Power Supply Board itself. Check connections at both ends of the cable and, if good, change the Power Supply Board. These are only generalities and there are exceptions to everything. Also, the assumption is made that you have tested input voltages and fuses where appropriate.
You can find the actual wiring diagrams in the Library.
RV Mobile Inc. 11715 HWY 99, Everett, WA 98204
The owner of RV Mobile Inc. apparently suffered a heart attack and the original website was shut down.
It has been reposted here to preserve this wealth of information RV refridgerator information.