How do you replace the PCM on a Mercury Mountaineer?

To replace the PCM (Powertrain Control Module) on a Mercury Mountaineer, first disconnect the negative battery terminal to ensure safety. Locate the PCM, typically found near the driver's side fender or under the hood, and remove the necessary connectors and mounting bolts. Install the new PCM by reversing the removal process, reconnect the connectors, and secure it in place. Finally, reconnect the battery and perform any required reprogramming or diagnostics to ensure proper function.