How do you remove the computer from the 1990 mercury grand marque?

To remove the computer from a 1990 Mercury Grand Marquis, first, disconnect the negative battery cable to avoid any electrical shorts. Then, locate the engine control module (ECM), which is typically found under the dashboard on the passenger side or near the firewall. Remove any screws or fasteners holding the ECM in place, disconnect the wiring harness and any attached connectors, and finally, pull the module out carefully. Make sure to note the orientation and connections for reinstallation if needed.