having a intermittent problem with transmission, while driving level ground staeady speed the unit will downshift and lock in second gear, the dr 4 light remains on, if selector is moved to any pos the dr 4 light still remains on as well as the selected pos, there are no codes showing, stopped the car at the bank dr through and had it in park, after 10 mins or so the dr 4 light went out and everything returned to normal. this same thing has happened about 8 times, mech says its elec but was un able to find the problem since he was un able to make the problem come up. need help here, also the speedomer worked normal throughout all this. i drove 185 miles since the last time it did this.
Frank Allen 92 accord lx

 

I am not sure which light comes on when the TCU detects a problem, but a manual like Haynes will definitely have that information. Its a $20 investement that will pay for itself almost immediately. A shop manual is definitely better, but it is more expensive.

I definitely think that you should short the two-pin service connector under the glove box and count the flashes on the TCU unit to identify the problem. I am not sure if the D4 or S light will flash to give you your code.

You should also drain, refill, and drive 3x to exchange most of the tranny fluid. Use honda ATF. Look for metal shavings in the initial drain. Also the solenoid screens and the solenoid itself can get clogged up and cause problems. Clean them out using throttle body cleaner.

 

replaced the tcu with a junk yard part, problem fixed it never shifted so nice as now, thanks
Frank Allen 92 accord