on the dash of my 90 dakota the brake light is on.the brakes are fine, does the light come on with the parking brake. my parking brake is off and the only way it works is if i push it all the way in and the last two clicks work.

 

Lite will be on if the e-brake pedal doesn't return all the way to the top. Aside from that, usually the proportioning valve will also turn it on, but, that would imply a problem in the brake hydraulics. Might be a low fluid sensor?

 

The light on my 90 has been on for several years and i can't figure out why. I read somewhere something about a wiring issue but I can't find that post anymore.

 

Got the same problem on my 1990 also (v6, auto).
Oz

 

I did some research and it seems like this is common enough I saw more than a dozen people posting about it in threads seeking a solution. Some newer models had the abs light come on along with the brake light.
I never saw a definite answer but some folks got it fixed by filling the master cylinder back up, some did it by changing a battery so battery disconnect might help, some fixed it by changing a sensor on the rear axle. I am not sure what that is.
One guy took the time to post that he had removed the dash and taped over the light.

 

On a 1990, if you don't have the ABS light lit also, it's not the ABS unit (and you may not have ABS of any kind on it; not sure when it was phased in - the rear wheel anti-lock or RWAL brakes.)

I'd check the parking brake (make sure to pull it ALL the way up).

I'd also go underneath, to the front proportioning valve, and disconnect the warning switch long enough to see if the light goes out.

If the light goes out, you've got a problem in the brakes (which said problem may be it's not been finished up bleeding properly, or was bled without the proper tool to KEEP the valve from shuttling back and forth!)

Again, if you don't have the factory service manual, GET IT. Troubleshooting is covered in that.

RwP