That lamp flashes the code when you put a jumper across the SCS connector. Just like checking for engine error codes - the CEL flashes the engine error codes while the "D" lamp flashes the transmission error codes.

 

 

There are a lot of different items that can cause the D4 light to flash. You will need to read the transmission codes to help narrow down the problem. Copied the thread below on how to get your engine codes. All you need is a thin paperclip to short a connector to read codes. Just count the D4 flashes instead of the check engine light flashes to get the transmission code.

https://www.hondaaccordforum.com/for...l-codes-35962/

 

D4 code-14 means the ECU is not responding to the TCU. The CEL light should be on solid which indicates the ECU computer is not functional. You can confirm that by shorting the SCS plug. A running ECU should output the codes on CEL or turn off CEL if no code is stored.

Two common causes of ECU failures are: 1) bad capacitors, and 2) faulty barometer inside the ECU. Capacitors replacement is quite easy to do but not the faulty barometer. Honda uses a custom barometer by Motorola which has gone out of business. The Motorola barometer was not designed to last 20 year. Getting an identical used ECU from junk yard likely will have the same issue. You may have to find a late model ECU for parts.

 

I thought 94's had both a TCU and ECU. I thought it was in 96 Honda combined them.

 

4-cylinder Accords had ECU & TCUs through 95, and switched to PCMs and OBD2 in 96. The 95 V6 was the first year for the V6 and had a PCM with OBD2.

 

Thank You. I was close enough then.