Is it both battery and brake light? If so, yes those are wired together when the alternator is failing.

Here's the fix
www.4x4wire.com/toyota/maintenance/alternator_brushes/


88 4R, 350 V8, R150 5 speed Sold <...uot; />
97 4R, stock, daily driver
98 Sienna, kid and dog hauler, wife's ride