Subaru Auto to Manual Transmission Conversion Basic Overview

Subaru Auto to Manual Transmission Conversion Basic Overview

Jul 7, '21

This post is a general overview of converting your Subaru transmission from auto to manual. We wish we could offer a product to make this simple, but because of the many changes in Subaru wiring between car models and years, we can't make a product that works for everyone. This works for non-CANbus cars only. For a full write-up, click here!

Below is a video of us helping Bucky Lasek with his Auto to Manual Swap


When doing an auto to manual transmission conversion on your Subaru, you have two options:

1. Do it yourself with the iWire Auto to Manual Connector Package. These packages are designed for three types of transmissions: NA, Turbo, and DCCD. We've curated the plugs and terminals for the swap but only recommend purchasing these connector packages if you already have a lot of wiring knowledge and skill. Our connector kits are only designed for professionals and experts, not your average home DIY-er. While we would love to write out all the steps to do it yourself, there are so many combinations and variations we can't. 

2. Find an equivalent bulkhead harness and swap it out. This option is best for your average DIY-er. If you plan to do this keep in mind that the bulkhead harness must be from the same year and model (ex: 1997 Impreza) for this to work. 

Common Cars Compatible for an Auto-to-Manual Transmission Swap:

- All Impreza models from 2007 and earlier.

- All Legacy models from 2004 and earlier.

- All Forester models from 2008 and earlier.

- All Baja models from 2006 and earlier. 

General Overview of an Auto-to-Manual Transmission Swap:

1. Finish all mechanical changes needed for your new transmission, like shifter linkage, pedal box, clutch setup, etc. 

2. Wire the Neutral Position Switch (CN-PL02016) and Reverse Lights (CN-PL02009). Choose the appropriate plug needed for your transmission (NA 2 - 2 pin plugs, Turbo Trans 1 - 4 pin plug, or DCCD 1 - 6 pin plug). The neutral position switch requires ground input and signal to ECU. The reverse lights require a key-on power source and output to the reverse lights. Two pins will be left empty for the 6-pin DCCD transmission plug and can be wired to a DCCD controller laterDCCD controller. 

3. Wire in the Vehicle Speed Sensor Plug (CN-PL03002-1). This requires power, ground, and signal output. More about speed sensors (they need to match the cluster) can be found here

For a standard Subaru Vehicle Speed Sensor, Pin 1 (Left side from the terminal end of the plug) is the signal, pin 2 is the ground, and pin 3 is the 12v key on power. Pin 1, the signal wire, needs to run directly inside the cabin to tie into the signal wire between the cluster and the ECU since this wire does not come into the engine bay.

 4. Wire in the Starter Relay Plug (CN-PL04020) and Clutch Switch for Starter Interrupt Plug (CN-PL02015). The starter relay plug needs to feed and trigger from the key. The clutch switch for the starter interrupt needs a ground-side trigger and output to the starter and ECU.

5. Wire in Cruise Control Clutch Switch (CN-PL02046). This can be installed in series with the Brake pedal switch so that depressing the clutch or brake will disengage the cruise. 

6. Ground the manual (MT) identification pin at the ECU. It should be noted that the MT identification doesn't change the mapping to a manual. If possible, reflash the ECU to a manual map. If reflashing isn't possible, you'll need to swap to a manual ECU. Leave the transmission computer plugged in unless you switch to a manual ABS pump, in which case you can remove the auto transmission computer.

  • For turbo models with reflashing capabilities, you can not use the Cobb AP to reflash from auto to manual map. If you have a Cobb AP installed, uninstall it first, reflash the ECU with a manual map using Open Source software, and reinstall the Cobb AP. Since the ECU ID has changed from auto to manual, the Cobb AP will recognize the ECU as a manual and install it accordingly.

When looking for the MT identification at the ECU, you want to find the ground wire with the "MT" note. Below are two different variations from 2 different diagrams.

7. For some models, the OBD2 communication wire goes to the TCU. For these models, you must depin this terminal from the TCU so your OBD2 scan tool can communicate with the ECU. If you notice connectivity problems with your scanner and the ECU after the auto-to-manual swap, this is likely the reason.


Purchase iWire's Auto to Manual Transmission Conversion Connector Package.


NA Transmission

Turbo Transmission

DCCD Transmission


June 2024 Update - iWire no longer offers our automatic to manual harness conversion service. We recommend using the above blog to make the wiring changes needed for your swap. If you are doing a full engine harness swap, we can convert an automatic harness to a manual harness as part of the merge service.