When vehicle is started, PZM requests information from other modules on Class 2 serial data line. DTC U1255 will set when PZM request information from a particular module, and that module is not "on-line". PZM will then use default values. DTC U1255 will clear when module providing the requested informations comes back "on-line".
1. Clear DTCs and cycle ignition. Check for DTCs. If DTC U1255 exists, use scan tool to establish communications with each module on Class 2 data bus. Repair or replace as necessary.
2. Check for intermittent open in Purple wire between individual control modules. If circuit is okay, replace PZM.
B2120 is for the seat and is not likely be the cause of the problem. Get U1255 resolved and see if other problems are cured as well.