Chris Bryant wrote:
The 12 volt power goes from the switch through a flame fuse, thermostat, then to the ignition module. Any of these can interrupt the power- a meter or test light will tell you where the power stops.
Those flame fuses are flaky, but all of them, including just a bit of corrosion on the board connector, can give that failure- power not getting to the board, since you get no fault light.
Been there done that. I have tested all connection points with a 12V test light.
NOTE to other DIYers. Use a 12V INCANDESCENT test light. it proves that the connection can pass about 250mA of current. A meter will only show that there is voltage there, NOT that it can pass current.
