This is driving me nuts. I have a 93' honda accord sedan 10th anniversary edition and when I turn the key to the on position I have to wait for the d4 light to turn off before I can turn it on, I let it sit for a little bit then turn it off and try to turn it on but the d4 light will come on and stay on after that and the car will hard start. No flashing codes or anything. Parts I have already replaced include a leaky gasket seal and the alternator. Anybody know what could be wrong? I would appreciate all the help I can get.

 

I have seen a handful of ECU's go bad, and the light stays on constantly. Reset the ecu (pull it's connectors or battery power for a few minutes), and see what it does. Did you buy it like this? Did it just pop on by itself??

 

More than likely it's the TCM

I have a ecu and tcm out of a 94 accord if you're interested.

PM me

 

I found out the problem. Took apart the AT Control Unit and there is a damaged resistor on the board. Thanks for the help guys.

Does anybody know if you have to program the replacement AT control unit? Or is it like plug and play?

 

you could just replace the resistors and caps.
but a replacement just plug it in.

 

sweet thanks