Once you have removed the ETA, there is a cover on the one side, held on by screws. If you take that cover off, you should be able to see a small circuit board and some wires.
IF...you are going to remove the ETA for inspection, order a new gasket first, as well as the molded rubber hose that sits towards the firewall. Might want to get some of that plastic vacuum line as well. (get 2 gaskets, just in case)

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

How much did the harness set you back? Sorry it didn't fix the immediate problem, but you'll be better off...

Getting ready to do this myself. What is the extent of your mechanical knowledge/experience?

-GH