Donald S.

HI MY NAME IS DONALD AND I HAVE A 1993 HONDA ACCORD AND I AM HAVING TRANSMISSION PROBLEMS WELL THIS IS MY SECOND ONE IT CHANGES FROM FIRST TO FOURTH THE D4 LIGHT IS BLINKING I HAVE CHANGED THE SHIFT SELINOIDS AND TWO TCU BOXES STILL DOING THE SAME THING CAN ANYONE HELP. THANK YOU

MAD_MIKE

Pull the code.
If the D4 light is blinking there is a stored code.
Passenger side kick panel.
Look for a two wire blue connector.
Jumper it
Turn ignition to II(ON).
Watch the warning lamps for blinking and record the codes down.
If there is a problem with the ECU or engine with a shared component the TCU will trip the code. Shift quality is also greatly affected with engine running condition, a transmission 'problem' in reality may be an engine running issue.

bloomin

I don't want to intrude on this OP but I have had the D lamp flash on rare occasion (perhaps a couple of times in a year)
four short flashes, which I believe indicates there is a problem with the VSS. However it ONLY does this as you turn it to
accessories position and BEFORE you start the car. I have no obvious driveability issues or strange transmission issues the car shifts normally just as it always has. Any idea what it could be mike?

MAD_MIKE

When turning the ignition switch to II(ON) all the warning lights will come on and then turn off. You can also hear the fuel pump prime at this time. Usually when the pump has primed and turns off so do the warning lamps. It's a pre-start check. D4/ABS/CEL/S-light/SRS(where applicable) will come on for a moment and then shut off. Oil light will stay on until the engine is started.
Code 4 on your car sounds more like an intermittent connection issue. Check the wiring to sensor, check the sensor itself. It can be removed, disassembled and cleaned. VSS controls downshifting, TCU uses the NM/NC/TPS sensors to dictate when to upshift.