ok i have a 92 accord lx. about 6 months ago the d4 light started flashing and then sometimes would constantly stay on. I only had 2nd and 4th gear. I replaced the TCM. That worked for about 3 months then it started doing it again. I tested both of the solenoids on top and side of the tranny and they tested good. i Bought another TCM but i dont wanna put it in then go out again. Can anyone help??

 

When the D4 light flashes it means that a code has been set, if the light is on constantly then it is a hard fault. Pull the code via the two wire blue connector by the passenger side kickpanel, jumper the connector, turn the ignition to II(ON) and read any codes from the CEL and/or D4 light.