Looks like an awesome forum ! I have a complicated issue. It's gonna make me sound like an idiot but here goes.

2005 V6 Accord old trans slipped, and shifted erratically, so I installed a JDM transmission and it does about the same thing.

No Codes, no check engine light.
Appears to start in 3rd gear, BUT if you manually shift to 1st it hauls ***, shifting to second doesn't shift, and when you go into drive it slams into second then 3rd. Drive mellowly around the block downshifts hit HARD.
Everyone says limp mode, but there is no check engine light, I have a 30 dollar scanner I'm not even sure it would see a transmission code.

From reading the FSM it seems like solenoid control system but everything seems to be hooked up correctly.
Fluid level is good, trans shifter seems to be adjusted.
What's got me flipping is this is so similar to the original issue it has to be a computer issue.

Any Idea's before I junk this thing?

Thank's in advance.

 

Not sure on the V6 but we know for sure that a JDM 4 cylinder transmission is not compatible with USDM cars.

To really diagnose what is happening you are going to need access to an HDS or clone.

 

I don't have a Check engine or a code, but I went ahead and ordered a decent clone scanner, 200 bucks but what the hell.
Ill report what it says tomorrow
thanks

Steve