Hi,Welcome to Just Answer, My name isXXXXX will be helping you with your appliance issue today.
So even when you shut the a the burner off the bottom left burner keeps clicking? With all the burners off? Do you have a full model number for this unit?
Okay I found the parts, the most likely issue is going to be the burner switch itself, however this comes with a wiring harness and all four burner switches are connected together and it comes in a kit, since not all four burners are clicking I would assume the switch the the burner that is clicking has failed and is sending a signal to the spark module,you would need to test the switches which requires a voltmeter and knowledge on how to test for continuity, you can order parts for this at the blue link below.
http://www.repairclinic.com/Shop-For-Parts?s=t-MGC5430-%3d%3de hope this helps thanks and well wishes, Bryan