My sister's '99 Honda Civic Ex's Automatic Tranny began to fail so we swapped it out. I got the replacement tranny from a shop that imports used japanese Engines and transmissions. After the swap was complete my D4 indicator began blinking and the check engine light went on. I got codes P0730-incorrect gear ratio and P0715-mainshaft/input turbine speed sensor. I researched and found that the problem may be the klinear solenoid. I swapped that out but problem persists. I also swapped out the mainshaft sensor already. The car seems to run fine other than slightly hard shifts, but I dont know if that is normal for hondas.

Any advice would be greatly appreciated.

 

First, you should go back to the place you bought it from and explain your situation..hopefully they will trade you for another trans.
If you have already swapped out the solenoid for a known good one, and everything looked clean.. your problem is internal. Either a clogged passage, or something is broken inside.. You can always try to repeatedly flush the trans, 2 or 3 times and on the 4th refill test drive it again. Of course to some people, myself included if i just bought a trans from a local shop and it was faulty i wouldnt waste any more money on trying to fix it i would demand a working trans. Its up to you GL

 

You will get that from a bad speedo sensor at times(rare occasion). But, more than likely it is because of an incorrect gear ratio between the two transmissions. They have a different tooth count which is why you are getting the code. No fluid flush etc..is gonna change that. If that is the case the only way to fix this is to install a true USDM transmission from a 99 EX and save all the hassle.

 

i thought the incorrect gear ratio was because of the jdm tranny but how do you explain the other code?

 

The advice i gave him came straight out of a honda service bulletin and it actually had both codes that he's getting in that service bulletin.. I looked it up because i read the post and was curious as well on how to fix such a problem. Im not doubting you, but if your correct does that also mean you cannot swap automatic transmissions from year to year ex: 92 to a 93,94,95 etc..? Or is it just the simple fact that one is USDM and one is JDM?

 

Its more of a question of gear ratio....DX versus EX on 96-00 model autos. That sort of thing. The automatics a very sensitive to that issue. I would do the simple checks as listed above for the speed sensor....wouldn't hurt to try it!!