Are you looking for the actual disconnect relay, or the switch that operates it? Also, you should have two disconnects, one for the chassis battery and one for the house battery(s). The one on the firewall is probably for the chassis battery and may be a manual switch rather than remote controlled. The house disconnect should have a switch inside the coach near the entry door.
You said "hood", but the Expedition is a rear diesel, right? The chassis disconnect will almost certainly be in the back, adjacent to the engine. Are you looking inside the rear engine hatch or somewhere else?
2004 American Tradition; 2014 Buick LaCRosse
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