i recently bought a 2002 honda accord v6 EX , it had some problems with the tranny some grinding noises in the reverse, and a flashing d4, well the tranny was in a bad shape but it was rebuilt, but the problem is till there , when the car is started theres seems to be no problem, as the car gains speed it tries to change into 2nd, but it cant, the rpm goes high and then the d4 starts blinking, once its blinking i have to drive it in "manual mode" selecting second gear to gain power and then switching to d3 for getting speed, the solenoids were tested and they were good, sensors were swapped for testing and made no difference, it was scanned and it came up with this code (P0780), both before and after the tranny was rebuilt. while scaning it also showed incorrect info, when selecting 1st gear on the stick, the scanner showed 1st, so all good there, it was same with selecting 2nd, but on d3 it showed 1st, same with d4, i guess because the car was stopped so it would select 1st, but when putting on neutral, the scanner showed reverse, and when the reverse was selected, the scanner showed other than reverse (i forgot what it marked, but it didnt showed the correct info.) what could it be? i already spent alot of cash into it and no go, its my first car and i dont have much more to spend on it,. its been done alot of checking on the mechanical part, but not so much on the electrical part, could it be a bad tcm?

 

Well thanks for posting to the HAF site. Your post is hard to follow as it is one long run on sentence. Essentially I would be asking you why it was rebuilt? I know it went bad, but there are very few places that can properly clean the case and the housing and thus the ports. Even Honda won't rebuild them, they put in a reman tranny as there is too much risk involved and several dealers that I work with have failed at the rebuild in the past. The cause to the trany issue is still not set in concrete, but it is believed to be a clogged port(s). If you had it rebuilt at a reputable place then all I can say is take it back for your issue as it is a common one IMO.

 

the tranny was rebuilt maily due to a grinding noise when selecting reverse, also because i took it to a honda dealer and they too say it was the tranny, they asked over twice of what i payed for the car, so i took it to an automatic transmision shop, they guy there who rebuil is absolutely sure that he rebuild it correctly, and he asures its an electrical problem, so i took it to BOSCH, whic is a expensive place to take my car but the have good equipment to scan it, they now say its a transmission problem. sorry for being long but its a complicated problem.

the person who rebuilt the transmission has rebuilt honda transmissions before.

 

Stop by a parts store and have them scan for the codes. The post the actual code on here. The code starts with the letter P and has four numbers, like p1234.

 

the code is P0780, all solenoids were checked and all work.

 

I am having identical issues.
-Codes are cleared
-Put the car in D4, car starts in 1st as it should
-will not shift into 2nd gear in d4
-check engine light illuminates, d4 light flashes, car shifts to 2nd or 3rd and will -not down shift to 1st in D4
-Can manually take the car into the lower gears.
-When in park, sometimes have to jiggle the shifter to let it release the key or get it to crank
-Checked all fuses
-Checked brake lights and brake pedal sensor
-Replaced Trans Range switch
-Replaced fluid with Honda trans fluid.
-Pulled out the computer and inspected for bad resistor or capacitor.
-Tested Solenoid A&B (one was slightly out of range (15-25 ohm) at 14.97)

 

I checked the signals from the ecu to the solenoids, while the car off i checked each signal of every solenoid, and then with the car on i did the same, and compared the signals to a table that is on the service manual, and the signals coming from my ecu are not correct, so i opened the ecu and checked the transistor for solenoid A, and the signal is incorrect even before the transistor, so the procesor is sending incorrect signals, i havent been able to get another ecu and one from the dealership is way too expensive for me, so i suggest getting hold of the service manual for the 1998-2001 honda accord v6, and check the signals from your ecu with a multimeter, or get a used ecu, you will have to take the new ecu to the dealership to get the key code reprogramed. also check that all the numbers are the same on the ecu, mine has 2 stickers with distinct code, makesure the new ecu has both stickers with the same codes as yours.

 

It is deffinatly a ground issue most likely cluster area