RCM needs resolder (you know this). But if the ABS/Dash lights and no Speedo persist: Clean battery ground to frame > Inspect and reseat fuses > Diag/Replace Wheel speed sensors > ABS Module.
This is a great video to understand/diag wheel speed sensors: This video explains why the Right Rear Wheel Sensor is the first to check/replace:
In my case. replacing all the wheel sensors did not correct the issue (which surprised me) and it finally was the ABS module itself. But you have to deal with the flowchart steps.
(ps.. its not the brake switch. when your brake switch goes (like mine eventually did) your brake lights are on all the time. thats it. ).