As the weather has warmed, a check brake system alert has been popping up frequently while driving. When a system check is done, it says brake system ok. When the message appears, the air conditioner also stops blowing cold. The fuses for the ABS module are good, the battery was tested and it was on "its last quarter of life". I read a forum that said it was probably the battery or alternator. I don't want to spend a bunch of money diagnosing, rather fixing.
My car has 104000 miles.
My car has an automatic transmission.
If your battery or charging system is low or not charging, then it could affect systems that require a minimum amount of voltage. This will trigger a failure light or stop working if the voltage falls below the set voltage. I recommend having a mechanic check your battery, if you have them repair it then the diagnostic fee may be waived.