There is a problem with the transmission.
Transmission error
That is normal operation.
Possibly a security system activation light.
You probably need to get your oil changed?
There are many reasons why the anti-lock light would turn on in a 1994 Ford Mustang GT. One reason are bad ABS sensors.
the transmission is in overdrive I don't have overdrive in my car but look at your gearshift because the small button on it should be how you disengage the system
if their is no slipping or any other transmission issues and it is just only the loss of overdrive try replacing the brake light switch
If it's a driver's side air bag it could be a broken clock spring under the horn pad. The light is blinking it doesn't say which side. How would you know.
There is a problem with the SRS in your vehicle. This is not a DIY repair. Take it to a professional ASAP.
overdrive is turned off. This is usually controlled by a button on the shifter knob. Press it to turn of the overdrive, push it again to turn it back on.
check brake fluid level.
Should be the parking/tailight/dash light fuse