Engine management light on,been on ages, no adverse symtoms. Had EGR valve blanked off and deleted. Thought it was eGR ,light was off for two days,came back on and had it read, P0684,  glow plug module implausable signal. took drivers side lower dash off.at knee level found a few relays see photo. any idea where or which  module is located. There is a relay on the right side of the battery,could that be it? 

Did you get this problem sorted regards nathan