Flashing D4 on the dashboard on 1991 Acura Legend

Flashing on the dashboard.

WHat does this mean?

Asked by for the 1991 Acura Legend
Mine did this right before my speedometer went out.If the speedo goes soon it is your speed sensor. I had this problem and found a speed sensor repair kit online. The kit cost $75.00 plus labor was much cheaper than a new speed sensor.
2 answers
ECU monitors transaxle operation. ECU contains a self-diagnostic system which stores a fault code if a transaxle electronic control system failure or problem exists. If a fault code is stored, ECU will turn on and blink "D4" light on instrument panel.