The oven has a distribution valve and ignitors are mounted for Bake and Broil. If the top burners won't light you know you have a bad DSI. But what if the oven don't work? You gonna need to do some checks at the J-1 connector on the DSI. Remember their is a 40 second delay built-in to the control for safety reasons. Lighting will therefore not be instantaneous. The gas distribution valve should have 216 ohms between all 3 terminals. Doing tests to the system requires both AC volts testing plus DC volts and that can cause you to fry your meter if you are not careful so pay attention to what you are doing.
That gas distribution valve gets the DC volts (8-18 VDC).
IMPORTANT: Do not attempt to operate it's solenoids with any other voltage supply. Not good! The ignitors require 120 vac to do their thing.
To recap: the gas distribution valve works on DC power while the ignitors work on AC. Refer to the service manual posted above for further instructions. If either side of that dist. valve is bad the whole shebang will not work.