As I was working on my 1990 Accord sometime last week something gave out in the transmission control. I had the key on, but the engine off and just happened to be looking right at the "S" light for the transmission when it flickered for a bit and then came on and stayed on... It's odd, I either get the car trying to pull out in 3rd or 4th gear (but can select 2nd) or it pulls out in 2nd and allows 1st to be manually selected. The speedo works, no CEL nothing blinking, justt a steady green "S" light.

I pulled the TCU, yep, two resitors and a cap were toast. I ordered new parts from Mouser, got them in and test drove the car.... same thing, no change. The board is burnt pretty badly, I had to clean some of the traces and solder the new resitors from the backside... but I am getting continuity where I'm supposed to, so my soldering is fine. When I pulled the TCU after the test drive, it was blazing hot.

The solenoids seem to be OK, they have a nice click when jumped to the battery and the resistance is in spec.

I can only find a TCU from a 1994 Accord locally. It's from a Honda salvage yard whom I've dealt with in the past (bought a bunch of Civic stuff from them). They are telling me that the 1994 TCU will operated the tranny in my 1990 just fine, but that I will get the blinking "D4" light.

That sounds a little off to me. Has anyone tried it? Is there a way to swap te pins around to keep the D4 light from blinking?

 

I've tried using a 94 TCU in a 92 before...yup tranny worked fine, but the D4 was flashing
I THINK it has something to do with grade logic but Idk

 

Well... hmmm.

I managed to find a computer from a '91 locally, but I'm a little worried about having the same failure. I've been told the '94 computers rarely fail, plus they are cheaper and easier to find. I just don't like the idea of having the D4 light blinking at me all the time.

But, between not having the car drivable or putting up with a blinky light.... I'll take the light.


And I'm really really bummed right now.

Found a guy with a bunch of parts .... new pistons and rods, an h23 head w/ tirbo manifold a straight 91 2 door body with a brand new c-fiber hood, nice wheels and tires... he couldn't sell it so he just gave it all away to get it out of his garage! I missed out!