If you have an electrical issue you've been trying to diagnose but can't find the root of the problem, the ECU (engine control unit) may be at fault. The ECU is an electrical device that controls the sensors and switches on the engine and is prone to failure because of electrical shorts or opens and water damage. If you suspect that the ECU is bad on your Range Rover, replace it with another that is operable to see if it solves your electrical issue.
Open and prop up the hood of the Range Rover.
Disconnect the negative terminal of the battery with a wrench. The negative terminal will be marked with a negative sign and has a black cable running to it.
Open the passenger-side front door.
Remove the door sill by pulling it up at the edge. The door sill is held on by plastic clips and will require moderate force to remove.
Remove the passenger side kick panel. The kick panel is a plastic trim piece directly to the right of where the passenger's feet would rest. The panel is held on with screws that you can remove with a screwdriver.
Remove the ECU with a ratchet.
Unplug the connectors going to the ECU by pushing down on the tab of the connector and pulling them directly outward.
Plug the connectors into the new ECU.
Install the ECU with the bolts you removed earlier with a ratchet.
Put the kick panel back in place and tighten the screws.
Install the door sill by pushing it down firmly until you feel the plastic clips snap into place.
Reinstall the negative terminal back onto the battery with a wrench, then close the hood.
