1993 Honda Accord D4 light blinking; can you help?

It sounds like a solenoid problem, which is under the hood mounted on the top of the transmission. It's easy to get to, but before you do that you should check the connector plugs for corrosion and/or damaged plugs. Or, it could be the TCU. The TCU is located on the passenger side floorboard under the carpet. It's not good if you burn a couple of resistors inside of the unit. The D4 light blinking indicates there is a diagnostic trouble code stored. When a malfunction occurs, the Honda Accord's computer records the code and stores it, then flashes the D4 light to let you KNOW there is a problem. On pre OBD 2 Honda vehicles, from 1995 and back, Hondas are manual code read which means you do NOT hook up a scan tool as there is no scan port. The passenger side front kick panel is removed, and a blue 2-wire connector located. Use a jumper wire to short out the connector, then turn the ignition key on with engine off and not running. This throws the computer into self diagnostic mode, and the D4 or "s" light will flash a series of flashes.The flashes have to be counted and written down. For example, 2 flashes followed by 4 flashes would be a code 24. The code is then looked up with reference material for a description and diagnostic route.Every diagnostic trouble code has a diagnostic route, for repairing the problem. Again, the diagnostic route is available in the reference material from pay sources like All Data Online. After the repair is made, the battery is disconnected, or just pull the 7.5 amp fuse in the fuse box under hood to clear the code. Good luck.