I keep seeing people telling you to disconnect the negative terminal to clear the ECU. This is a poor choice and will result in having to reset the radio presets and the clock. Simply go to the main fuse box located on the passenger side inner fender. Remove the 15amp fuse in position 37, the info is printed on the fuse box. This will clear the computer codes without effecting any other circuits.

Before replacing the main relay, check that the pins in the connector show the correct voltages. If you don't have power to the relay a new one won't work either.