2003 Toyota 4Runner Transmission Leak into Electrical Harness (ECU)

toyota
4runner

#1

My wife has a 2003 Toyota 4Runner Limited AT with 140k miles (10 years old). We have gone through all the O2 and related sensors
the last several years (B1-B2 S1-S2). The sensor (B2S2) that reads the catalytic convertor and the transmission electrical harness
wire cover have become filled with transmission fluid. The electrical harness has moved fluid into the ECU (behind the glove box).

Any idea as to what may have caused the transmission leak? and suggestions on repair options?

The attached pdf is a similar issue (with another vehicle).