Greetings FTE folks!
First post...bear with me. I have been reading for 6 months and learning daily..so firstly I would like to thank you for my newfound knowledge.

I have a 2000 Excursion 7.3 4x4 Limited with 225K on the clock. It runs strong and I don't notice any issues. I recently picked up a OBDLink LX and have Forscan on my laptop. I was getting a flashing OD light for a bit after I drove thru the snow the other night, it happened exactly when I went back into 2wd. I will post my codes and list the work I have done. I would appreciate some assistance in interpretation with these as some make no sense to me. I was not expecting this many codes. There is NO Check Engine Light on at the present moment...never has been.

DTC B1681 - No transceiver signal received from the module/no transceiver detected. (No clue what this even means)
DTC P0475 - Exhaust pressure control valve malfunction (might be from the delete?)
DTC P0720 - OSS sensor circuit fault (No clue what this means)
DTC P1211 - Injector Control Pressure Higher/Lower Than Desired (engine running)
DTC P1316 - Injector Driver Module Codes Detected (No clue again)
DTC P0238 - Turbo/Super Charger Boost Sensor A Circuit High (brand new MAP sensor)
DTC P0478 - Exhaust pressure control valve malfunction (also from the delete?)
DTC P0722 - Output Shaft Speed Sensor No Signal (transmission related?)
DTC P0541 - Manifold Intake Air Heater Circuit Low (this has been deleted)
DTC B1203 - Fuel sender circuit short to battery (no clue here)
DTC B1428 - Safety belt lamp circuit failure (I think this is from not having a bulb....needed it for 4x4 which was burned out)
DTC P1876 - Transfer Case 2-Wheel Drive Solenoid Circuit Open Or Short To Ground (I suspect this is causing the OD light to flash)
DTC P1865 - Transmission Transfer Case Contact Plate Power Short to Ground (I suspect this is also causing the OD light to flash)

What I have done so far....

Suspension/etc..: X codes in front and modded B codes in back, Bilstein 5100 all around and steering stabilizer, cleaned pickup filters in tank, new Bosch fuel pump, Edge Monitoring system with air pressure attachment (boost)/EGT monitor/Transtemp, all new fluids, upgraded headlights to clear lenses and all other bulbs to LED, Pioneer DVD player, LED relay.
Engine: S&B Intake with MBRP 4" exhaust, new MAP sensor, 203 degree thermostat, Dieselsite coolant filter, new water pump, RiffRaff boots and plenum inserts, International bellowed up pipes, turbo rebuilt with 4 way thrust washer and WickedWheel2, EBPV pedestal delete, new EBPV sensor and tubeDieselsite mechanical wastegate controller, new Degas bottle and cap, new GPRM, has a TS chip but I am unsure of the tunes (guessing stock).
Transmission: 6.0 trans cooler, Dieselsite trans filter, John Woods valve body, bypass removal kit (per his recommendation), trans only gets up to 225 now...not sure if that is too low or not, I recently replaced the vacuum hoses that connect to the frame and hub.

Any thoughts on these errors? I hope I have provided enough info for you folks.....again, I was not expecting this many.
I will be around all this weekend....back to LEO academy on Monday and home again next Friday....I am online in the evenings too.
Thank you!