It is DOT3. It is listed in your owner's manual and on top of the master cylinder fill cap.
Dot 3Dot 3
DOT 3 brake fluid.
Dot 3
ATF
any brake fluid that has a DOT 3 rating will work
dot 3
Dot-4
DOT 3
DOT 3 brake fluid.
Mopar ATF+4
As with any other vehicle, this would indicate either a brake fluid leak, an empty brake fluid reservoir, or the failure of the brake master cylinder piston seals. It should go without saying that the vehicle in question should not be driven until the brakes are completely and properly repaired.
In my 1989 Dodge Dakota the brake light is on fuse number13 it is a 5amp it also goes to buzzer, speed control, check engine light, anti-lock warning light, and other things page 12-19 Haynes 1987- 1993 Dodge Dakota Repair Manual