In the last week or 2200 miles my 06 keeps throwing the fcm internal code. Wondering if this was related. The coils or grid heater light randomly comes on while driving. Now im also getting a fuel delivery error. Left trailer tow light over current. Ignition over current. Could this all be related to the fcm?

 

Try pulling the connector and re-seating it...they sometimes get a bit of corrosion on those multi-pin connectors even though they are considered weather proof.

 

The 06 doesn't have an FCM, it has a TIPM. The trailer light and ignition over current is likely a shorted wire somwhere at the back or in the light bar of the tail light.

The grid heater randomly coming on is a DTC for fuel return high. Could be bad injectors or electrical issues. Time to start checking connectins and wiring.