The electronic control module (ECM) on a Lincoln Mark VIII controls the power train systems for the vehicle. The ECM monitors input from all the various engine and transmission sensors, as well as the fuel and emissions system sensors, and uses that data to control the entire power train. As with any computer, the ECM on a Lincoln Mark VIII can malfunction. If that happens to your Mark VIII, you may find yourself unable to drive the vehicle until you replace the ECM.
Open the Lincoln Mark VIII's hood by hand and support it on the prop rod if your model year does not have hood struts. Disconnect the Mark VIII's negative battery cable at the battery using the battery wrench.
Push the vehicle harness retaining clips off the harness connectors where they meet the ECM. The ECM is a steel box that mounts by the firewall, just below the cowl on the passenger side.
Pull the vehicle harness out of the back of the ECM by hand. Push the wiring harness away from the ECM so you can have access to the ECM mounting bolts.
Remove the ECM mounting bolts using the socket set. Lift the old ECM out of the Mark VIII's ECM bracket in the engine well, and set the new ECM into the ECM bracket.
Plug the wiring harness into the back of the new ECM. Close the vehicle harness retaining clips down over the harness connector to ensure the connector does not vibrate loose during vehicle operation.
Reconnect the Mark VIII's negative battery cable with the battery wrench. Shut the Mark VIII's hood.
