OK folks I think I fixed the problem. I found out there was no 12v signal going to the relay from the control board (yellow wire to the relay). Thor told me to check the appliance fuse inside the RV to make sure they were working. That fuse was ok and 12 volts was present at both sides of the fuse. He then suggested I look for a reset button on the control board of the water heater itself. I didn't find a reset button but I did find a small 2 amp fuse that when I tested found 12 V at one side and not the other. When I removed the fuse and tested for continuity, it was definitely blown. Went to auto supply store and picked up a package of mini spade fuses containing a 2 amp version and put it in yesterday. Now 12 volts was present at both sides of that fuse. With the heater black lead removed earlier, I went inside and turned on the 120 volt switch for the water heater. There was now 12 volts present on the yellow wire. I plugged it into the relay and heard the relay close. I also was now able to measure the 120 volts AC going to the heater lead. So I put everything back together yesterday and plan to fill the water heater with water and see if it actually works today.
Keep in mind the relay is located on the inside of the heater meaning the entire unit had to be removed. The fuse on the control board is located on the front of the unit and was easily accessible.
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