Atwood WHs since 2004 models have fault light for Propane NOT lighting/proving and/or 'IF' the ECO Opens (Energy Cut Out---hi temp t-stat)whether on electric/propane
IF WH is combo electric/propane On/Off switches are on common panel
(2003 and prior...fault on propane and electric On switch local on cover over element on backside of WH Tank)
Suburban uses fault light if propane not lighting/proving
Suburban electric.....OEM on/off switch is in outside compartment. Lower left corner
DSI...Direct Spark Ignition.
High voltage spark electrode used