Brake Warning Light Always On

Asked by JustVisiting4Now Nov 24, 2023 at 04:58 PM about the 2003 Ford Mustang Coupe RWD

Question type: Maintenance & Repair

I have this project car I have been fixing, but after replacing and
programming the ABS Module, my Brake Light stays on. my brakes function
normally, but my transmission does not want to go in gear. it eventually does
go into gear while idling in D for a few minutes, but slips out of gear when car
comes to complete stop. Recently replaced dead battery and all codes are
reset, but cant test drive in current condition. Is there a particular component
in the Brake System that communicates with the transmission? or are these
2 separate issues that are just coincidence. Also, I cant find anything on web
about resetting the TCM for the 2003. everything online seems to be 2009 or
newer.

1 Answer

310,085

If the transmission will eventually go into gear after it warms up then you have an internal transmission problem, most likely the seals are gone. There is no direct relation with ABS and the transmission. To reset the TCM just unhook the battery for about 5 minutes, but as you already have done that when you replaced the battery. Check the park brake light switch, the brake fluid level sensor.

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