My initial problem was that my unit was producing ice very slowly. Service test 56 gave an E5 response code (Ice maker thermistor bad) while the other ice maker related tests were fine. Water dispenser was also good (matters for my current problem).

Ordered and replaced the ice maker unit. All tests were normal last night though I did not run test 19 for the fill tube and fascia heater. Got up this morning and water would not dispense.
Checked the lines and they were frozen. I attempted to run test 19 and I got a code of 3.
According to the tech sheet 01 is On and 02 is Off and that's it. If I try to toggle the heater on/off all I get back is the 3. I have no clue what a return code 3 means. Can't find anything useful on the net.

I tried to check voltage on the wiring harness for the heater and got nothing, but without knowing for sure the heater is turned on with a response code of 01 I'm not sure that's invalid. I would check resistance on the heater line itself but can't find anything to tell me what a valid reading would be. Also since it's a split wire going to the feeder heater and the fascia heater I'm not positive how to actually check that (I'm not very good with a multi-meter but I usually can limp along ok for basic stuff)

I'm afraid that code 3 is some error code that means I'm going to need to replace the main controller board but I hate to do that unless I know something for sure.

Does anyone have any suggestions here?
Thanks in advance!!