blinking D4 light in 92 accord

i have a 92 accord ex automatic. i just recently bought the car and noticed when i was driving it a couple days ago that the D4 light on the automatic transmission display in the gauge cluster started blinking. it blinks when i drive in D4 and even if i drive in D3 the light on D4 still blinks. yesterday the tranny made some kind of clunk and now the car shifts perfectly fine into drive and all the other gears but going from drive into nutreal, park or reverse it makes a loud clunk. any help on this would be greatly appreciated.
thanks

It is telling you there is something wrong with your tranny...one of the more common problems is the Transmission Control Unit (TCU aka TCM). Check to see if your rpms jump around at all while driving...the TCU is located under the passenger kick panel...it is quite easy to remove and replace with a few socket wrenches and 15mins...however getting a good one is the difficult part. They run new for $400-$600...it is better to try and find one from a junkyard or from a person on this board parting out their accord...as I did.

However, this doesn't necessarily mean that it is the TCU...are you getting any Check engine lights on the dash? I would suggest either going to Autozone and see if your local one will run codes for you to find out what the specific problem is, or check them yourself...directions are here:
http://www.hondapitstop.com/accord/technotes1/engine/error_codes/error_codes.html

This code will tell you specifically where the problem lies...