ECM location

Should be located in the air cleaner box compartment. These are the steps to remove the ECM/PCM/Computer shown in the GM Shop Service Manual, Revised May 2010 that I have: Note - To avoid possible voltage spike damage to PCM, ignition key must be off, and the negative battery cable must be disconnected before unplugging the PCM connectors. Once PCM is located isolate other air cleaner housing components : 1. Disconnect the negative battery cable and isolate. WARNING: If the negative battery cable is not disconnected the possibility of damaging the Powertrain Control Module by contacting the Positive battery cable at the PDC. 2. Remove the nuts holding the PCM and bracket. 3. Unlock and disconnect the electrical connectors at the PCM. 4. Remove the fasteners holding the PCM to the bracket. 5. TECHNICIAN MUST USE THE SCAN TOOL TO REPROGRAM THE NEW PCM WITH THE VEHICLES ORIGINAL IDENTIFICATION NUMBER (VIN) AND THE VEHICLES ORIGINAL MILEAGE. IF THIS STEP IS NOT DONE A DIAGNOSTIC TROUBLE CODE (DTC) MAY BE SET. As you can see, it is a delicate procedure for anyone not having the required knowledge, skills and tools. So, be careful if you plan to attempt this repair on your own.

The other good news is (you need to double check) the Lucerne ECM is probably the same as the Cadillac DTS ECM Since both cars have the Northstar engine,