First symptoms: Stopped at a stop sign in D3, tried to accelerate and the RPMs shot up but the car didn't move (or moved very very slowly). (D4 light is now blinking) Down shifted to 1st and car moves like it should in 1st.

I drove it for a year sometimes having to shift manually. The D4 light would randomly come on and then it would stop accelerating when in D3. If I shifted it manually it would get me around fine, but drive a little rough. Eventually the D4 light started flashing all the time, but the car wouldn't always need to be shifted manually. After a year of driving it like this, it has started to slip out of gears while accelerating, where as it was always from a stop before. It seems to do it in all gears, but more likely in 1-3.

I had my oil changed and was told that the transmission fluid was very dirty. I drained and filled 2.5qts yesterday. The smoothness of shifting seemed to improve some, but it is still slipping gears while accelerating after 10 or so minutes of driving.

I just pulled out the TCU and checked out the circuit board. I can't see anything that looks corroded, fried, goopy, etc. I thought for sure it had to be the TCU based on symptoms. Any ideas??

 

Pull the code for it first. Second if the shifting improved, drain fluid again and fill. Use 3 quarts of Honda ATF.

 

I got Code 2 from transmission (D4 light) and Code 43 from CEL.

I was on my way to a transmission shop today to have a diagnostic, and half way there I had to coast into a parking lot and have it towed the rest of the way. It slipped out of gear while in 2nd, I shifted down to 1st and still had no power. Giving it a lot of gas was not gaining me any speed so I pulled over. I shut it down and started again thinking I'd try to get the rest of the way and as I was waiting to pull out I heard a flapping sound I hadn't heard before. So I decided not to try. Will find out sometime Monday what they find.

 

The mechanic said it's the transmission filter and most likely a lot of debris from wear clogging it up. Since Honda filters can't be easily replaced, I'm out of luck.

 

Do you have the car back or is it sitting at the shop?

 

It is still at the shop until I can get a ride to pick it up.