My wife's 97 honda accord dx D4 light flashes and I don't know why dose any one know the reason or possible reasons why thank you

 

The D4 light flashing means the car's computer detected a transmission problem and stored a specific code. You need to determine the code before you troubleshoot further. I would stop by a parts store and have them scan for code(s). Your connector is behind the ash tray.

You can also read the thread called How to get CEL codes in the DIY section if you want to do it the OBD1 way.

Post the code on here, and we can help you figure out the problem.

 

I took the car to Auto Zone to get the codes and it came up with Catalyst system efficiency below threshold bank 1
Probable cause
1. A/F ratio concern
2. Air leak near HO2S (heated Oxygen sensor)bank 1
3. Ignition system concern
4. faulty catalytic converter

Or Lock up clutch does not engage- stuck in 4th gear
Probable cause
1 Open or short circuit condition
2. poor elecrical connection
3. faulty lock up solenoid A
The car shifts fine only when it down shifts do I see the RPMs drop and then go where they should realisticaly the car runs fine and it is a automatic taransmision so I know there is no clutch please help thank you

 

also the trouble shooting # are P0420 and P1753

 

The P1753 is the problem that is causing your D4 light to flash.

Check that the lockup solenoid is plugged in. See attached picture for location. You can unplug the connector, and measure the resistance between the yellow pin and ground (I use a valve cover bolt). The resistance should be between 14-25 ohms.