Where is the ECU location
The the ECM (Engine Control Module) became the PCM (Powertrain Control Module). It is located under the air filter box for cooling purposes.
http://www.vadengmpp.com/owners-manual/cadillac/2001-Cadillac-Deville.pdf Chapter 6 Page 68 for fuse
A picture of the ECU on the 2003 Cadillac deville
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