gshort, recently we have found two 8FGCU25 models in our fleet where battery acid had leaked from the left front corner of the battery tray and puddled on the cover of the ECM/junction center mounted below the battery tray.
I don't know what material Toyota uses (plastic or resin?) to make the cover for this electrical center but I can tell you that battery acid will attack and damage it.
The first truck had a strange complaint about the transmission suddenly disengaging while traveling so we first began checking the OPSS (seat switch) circuits.
Not finding any fault in the seat circuits per se, we looked further.
The tech working that truck discovered holes in the ECM/junction center cover and removed the cover to look inside.
In the very bottom of the junction center are some cam lock harness connectors. He unlocked the connectors and you could see green corrosion traces had formed all across the bottom of the connector bodies.
We cleaned out the green stuff with electronics spray cleaner followed by blasting out with compressed air nozzle.
Then we sprayed electronics grade dielectric coating on both halves of all connectors.
We are currently beginning to work on a solution/remedy for this and so far we have decided do the following:
Clean the acid damaged area of the j-box cover and seal the holes in the cover with RTV.
Clean the battery tray and apply RTV to the left and right front corners of the OEM battery tray to form a "dam" against any further acid leaking off at those locations.
Drill a 5/16" dia hole in the floor of the OEM battery tray in the right rear corner of the tray.

Though our complaint was about travel malfunction, I would hazard a guess that mast functions could be affected too, since the cause seemed to arise in the OPSS circuits in the j-box.