Tacoma Multifunction Steering Wheel Failure

Sounds frustrating. The fact that all the functions are out points away from individual sensor issues. Have you checked the clock spring? It's essentially a rotary electrical connector that allows the steering wheel to turn while maintaining electrical connections to the airbag, horn, and all the steering wheel controls. A break in the ribbon cable inside could cause a total loss of function.

The clock spring... good call. I've heard horror stories about those. Is there a way to test it without just blindly replacing it? I'm vaguely familiar with the concept, but are there specific pins or voltage readings I should be looking for with a multimeter?

Testing the clock spring requires caution due to the airbag. Disconnect the battery and allow sufficient time (at least 30 minutes) for the capacitors to discharge before disconnecting the airbag. There are diagnostic procedures involving resistance checks between specific pins on the clock spring connector using a multimeter. However, without the specific wiring diagram for your 2002 Tacoma, pinpointing the correct pins is difficult and potentially dangerous. Given the symptoms and the error codes you're seeing, a damaged cable connection in the steering wheel is the most probable cause. Honestly, for the sake of safety and accurate diagnosis, a trip to a trusted workshop for proper diagnostics is recommended. They'll have the correct tools and information to safely assess the clock spring and pinpoint the fault. Continuing without the proper documentation is unwise and risks damaging additional components.

Big thanks for the sanity check. You're absolutely right, messing with the airbag without knowing exactly what I'm doing is asking for trouble. Dropped it off at the shop this morning. Turns out, it WAS a damaged cable connection in the steering wheel, just like you suspected. Repair cost was 95€. Much appreciated!