Hello everyone,

I am posting today looking mostly for clarification on something I have discovered while attempting to sort through electrical issues on my recently manual swapped 03 G. This is my first post so I apologize if i got it in the wrong section

About a month ago the opportunity rose to purchase a manual 04 G that was in running and driving condition for a steal ($1000 Canadian). As I have been looking for something like this for a while, I purchased it and began the swap.

Since I had 2 complete running & driving G's to start with (1 auto & 1 manual) I wanted to do things the 'right' way and swap the drivetrain and replace all the auto electrical with the manual electrical. In doing so I proceeded to remove the Engine Control Harness, Main Harness, IPDM, BCM, ECM, Cluster, ABS computer, key barrel and install it on my previously auto G. When I went to remove the Engine Room Harness I noticed that it passes behind the firewall under several hard lines so I decided to leave it in and attempt to make the auto one work.

I was able to get everything installed and plugged in, I wired up the clutch switch to the IPDM. The car would crank but not run. It was throwing several codes related to the throttle pedal sensor, throttle actuator, VVT solenoid, and Evap vent control valve. Thinking it would just be an easy wiring fix I got out the FSM and started going through the procedures to diagnose the issues causing the codes. This is where things began to get weird.

Before digging into the FSM I decided to check the VIN on the Manual G to see what year FSM I should use.
Manual G VIN: JNKCV51E83M326517 This indicates that despite being registered as a 2004 the VIN says it is an 03. I dug into the 03 Engine control section, as the car was a manual it had the Type 2 ECU. While I was going through the procedures listed to diagnose the Accelerator Pedal Position Sensor, Electric Throttle Control Actuator, & Intake Valve Timing Control Solenoid (Bank 1&2) (checking voltage across connection pins and looking for continuity between wires) I began noticing some very odd concerning things. The FSM was telling me to look for continuity between pins on the ECU connector that had not been pinned up.

Realizing this I stopped following the procedure and began trying to locate where on the ECU connector the sensor, actuator, and solenoid were hooked up to. In doing so I have found that whatever variant of 03 manual G I have, the ECM is pinned up in a completely different way from what is listed in any service manual. I have uploaded a picture of the supposed ECM pinout showing how the 3 components I checked were pinned up.


ECM Pinout from FSM updated with how my G was pinned for a few sensors


So what does this mean? If I were to re pin it according to the FSM and how it should be wired, the ECM, which worked when I drove the car home would definitely no longer work. Do I need to revert right back to an early 03 harness and run an auto ECU? I am just very exhausted and confused at this point, so any insight as to why this manual G is like that and how I could potentially make my car work with all the wires that are currently installed in it would be wonderful.

Thanks,

Liam

 

Yes that's correct, you will not be able to use that existing engine wiring harness, the pinouts are different between the 5AT and 6MT. Take the 6MT harness and use it with the 6MT ECM and BCM.

Plus the existing 5AT harness probably doesn't have the correct electric fan wiring.

Or you can just repin the harness for the correct layout, it would be a little tedious and I think you have to add wires.

 

So just clarifying, I already have the Engine control harness installed (runs from ECU to engine and controls EFI, spark....) as well as the dash harness( runs to all the interior control stuff and cluster) from the 6MT installed on the Auto. So you are saying that I am just that one last harness that wraps around the engine bay and goes to the headlights and stuff away from being finished?

If this is the case does anyone have experience removing that harness without disconnecting all the hard lines going to the heater core?

 

Look at this post, which ECM do you have?

https://g35driver.com/forums/tuner-d...ml#post7161576

 

The ECM that my automatic G came with is the older box style in the top of the picture in the post you linked

The ECM that m 6MT G came with is the second ECM in the pic of the post you linked