There should be a plastic 'see through'window in the bottom back corner of the fridge . Provided the pilot sized flame nozzle isn't blocked you should see the flame.You should also hear a faint 'Pop' as it lights.
Change the knob to the gas setting and hold it in whilst you operate the igniter, it can take a few seconds to ignite but if you have air in the pipes after changing a cylinder it will take a lot longer. Try purging as much air as you can through the cooker.
The 12v circuit will only operate when the alternator is producing more than 13.5 volts. This is to protect the vehicle battery from being drained.
Cledlyn
August 2008