ECM 97 Yukon waterdamage?

97 Yukon, noticing on alum ECM case corrosion where 2 halfs of case meet. Anyone ever had or seen water or corrosion damage inside there on circuit board. It looks like several allen(maybe torx) head screws holding the 2
halfs of case together, if I want to split the case and check out inside is there any precautions to take. The truck has been acting up intermittently and no codes will show when it does, thats why I want to check out ECM. Can the Dealer or garage bench test ECM?...Thx Rico.

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