Can I reboot the on-board computer by disconnecting the negative battery terminal, wait five minutes, then reconnecting it?

You may need to reset the computer (Engine Control Module or ECM) in the 2014 Ford Fusion if you are experiencing performance problems, have recently performed maintenance, or are trying to clear fault codes. Here's how you can do it: Note: Resetting the ECM will erase any stored fault codes and variable learning data, and may affect your vehicle's performance unless it relearns optimal settings. If you're not experiencing any problems, it's probably best to avoid resetting the ECM. How to Disconnect the Battery: Disconnect the negative terminal: Locate the negative (black) battery terminal. Use a wrench to loosen and disconnect the negative terminal from the battery. Make sure it is safely away from the battery. Wait: Leave the terminal open for about 15-30 minutes. This can remove any residual energy from the vehicle's electrical system, restoring the ECM to normal operation. Reconnect the terminals: Reconnect the negative battery terminal and tighten it. Reset: Start the vehicle and operate for a few minutes. Take a short test drive with different driving conditions to allow the ECM to relearn its settings. OBD-II Scanner Procedure: 1.1. Get an OBD-II scanner: Buy or borrow an OBD-II scanner. Make sure it matches your 2014 Ford Fusion. Look for an OBD-II port: The OBD-II port is usually located under the dashboard, near the driver's seat. Insert the OBD-II scanner into the port. Turn the ignition: Without starting the engine, set the ignition key to the "On" position. Accessing the ECM: Follow the scanner instructions to access the ECM reset function. This can be labeled "Clear Codes", "Reset ECM," or similar terms. Reset: Use the scanner to initiate the ECM reset. This will clear any stored error codes and reset the ECM

Disconnecting the battery can sometimes cause the vehicle's computer to reset, which can result in it entering "limp mode" to protect the engine and transmission. This mode is designed to limit the vehicle's speed and power to prevent further damage until the underlying issue is resolved.
To get your truck out of limp mode, you may need to reset the vehicle's computer by following these steps:

1. Turn off the engine and remove the key from the ignition.
2. Disconnect the battery terminals (both the positive and negative cables).
3. Touch the positive and negative cables together (away from the battery) to discharge any remaining energy in the system.
4. Wait for at least 15 minutes before reconnecting the battery terminals (first the positive and then the negative).
5. Start the engine and see if the limp mode has been resolved.

If I remember correctly you disconnect the battery for ten to sixty minutes, reconnect battery and the computer starts the relearn process.Good Luck Friend.

Try disconnecting the negative battery terminal. Wait for a minute, then reconnect. Sometimes this reboots the system and things start to work.

Not sure if this will work but try disconnecting the negative battery terminal and wait five minutes before reconnecting it. Doing this may reset the security light.

DISCONNECT THE NEGATIVE CABLE AT THE BATTERY,THEN WAIT FIVE MINUTES THEN RECONNECT,WHAT HAPPPEN?

Unplug negative battery for few minutes; then reconnected and, if the check light tuno on again, I suggest scanning for knoew what code fault have there.

Hope help (remember comment and rated this).

You can disconnect your negative battery terminal, wait five minutes or so, then reconnect it. This should clear the malfunction code. If, however, you have an anti-theft radio, make sure that you have the five digit code to reset it after disconnecting the battery. Disconnecting only one terminal might not effect the radio, but I wouldn't count on it.
If the malfunction code comes back after you disconnect the negative terminal, then something has gone wrong with your repairs.
Hope this helps you.

Disconnect both the positive and negative terminals from your battery and let sit for about 5 minutes and reconnect. This will reset your system and check engine light will go off...

It shouldn't be,however.....when replacing batteries,or simply disconnecting and reconnecting to clear a code for example,always hook up the positive terminal first and the negative terminal last,and,with the ignition OFF.Infrequently,if a battery is hooked up with the key in the ON position,it can damage the vehicles computer....(PCM,TCM,BCM,etc etc)And the reason for hooking up the negative terminal LAST is to avoid arky sparky's off of your wrench which can also damage the vehicle's computer (s).Try disconnecting both negative terminals of both batteries and let sit for minimum 20 minutes,then reconnect,and see what you have.