Our8thGens

Ive been researching this for some time and im finally going to do it. I know im not the first to attempt this but ill probably be the first successfully do it on a USDM 8th gen sedan. Very few parts are actually needed for the retro. The basic parts you will need are paddle shifters and steering wheel harness, ECU & Speedometer from a coupe w/paddle shifters and some basic wiring skills. Some other parts can be installed but are not necessary to make it work (coupe shifter & escutcheon, etc.) but i will be installing these because im going for the "factory installed" look. keep in mind this will be a long term project so it may take me a few months to complete as i need to get most of the parts before i can do the retrofit. the hardest part to get (and most costly) is the ECU from an 3.5L with paddle shifters. Im going to be getting a used ECU because i dont want to spend $700 for new. The 2.4L ECU's are easy to find so you guys will have a much easier time getting parts than me. You will also need to get some parts programmed at the dealer. You will need to get the ECU and the speedometer mileage reprogrammed. the ECU will need to programmed with the VIN and the immobilizer/key. I will start by installing the paddle shifters and harness since they will not affect anything while the retro is done, i still have to use this as a daily driver. The speedometer is plug and play since it uses F-CAN for the displays etc. ,so this can be installed also, but im not sure how it would display 2, or 1.
The clockspring, gear selector switch and transmission are exactly the same so that makes this much easier. only a four pins on the ECU need to be swapped and some minimal wiring needs to be changed or added. If you have a coupe you could just change the engine wiring harness if your not comfortable doing the wiring changes.

i finally started ordering parts. got my speedometer coming and the paddle shifters and harness, still havent located an ECU yet.

wow, this is awesome. More updates please!

wow i got real lucky i found a ECU for $105, total so far $270 not bad! now i just need to find out how much the flash is gonna cost. with any luck this will be under $400 mod.

Wow, very excited to see how this goes. Keep it up!

Now on to the wiring changes. this part blew my mind because i thought it would require lots of changes turns out its simple. the wire from connector A pin 36 gets disconnected and combined with the circuit from connector C pin 11.



And the wire from A37 gets disconnected and combined with the circuit from C15



So now A36 becomes the Shift up input for the paddle shifters and A37 becomes the shift down input.

The connection from the Transmission range switch to the ECM from the 1-2 position is no longer needed since its selectable from the paddles. so it gets disconnected either at the ECM (C35) or the switch at pin10.


On the shifter D3 now becomes the Sport mode and 2,1 no longer work. you can opt to either use it this way or get the shifter and escutheon from the coupe with paddle shifters. the only difference between the shifters is that one has a stop that prevents it from going past the S (D3) position. so you could also just use your current shifter and get the escutheon because 2,1 does nothing anyway.

i installed the coupe gauges today and everything went well. most of the lights work like before the only things that didint light up were the S when i shifted to D3, and the wrong traction control light flashed when losing traction. i kind of expected that though because the software in this ECM cant address those lights. Wednesday the rest of the parts will be in and i can get the paddles installed then its just a matter of wiring and installing and flashing the new ECM.

this is possibly one of the best threads! very creative and probably the first to do it!

ok so i talked to a tech at the local dealership and they are willing to do it but they cant warranty the work which i am ok with. he was unsure it would work and told me they have never done anything like it before. they are going to schedule a 2 hr appointment just in case but he said we would know quickly if it wouldnt work so an hour should be all we need. they charge $99 an hour labor so im looking at a total cost of $370 for the retrofit. so well know next week if this works or not.

update
The wiring is done and the paddle shifters are installed I didnt hook up the wires to the paddle shifters yet because i still have my stock ECM in it and that would cause a short if the paddles switches were used and possibly do some damage so ill wait till after the ECM swap. I did start the car and everything runs perfect, now i just need to get it to the dealer and get the ECM swapped and flashed. Heres a little teaser shot of the steering wheel with the paddles installed. Ill do a diy with pictures later and ill post the template i made for the cutouts on the steering wheel cover.