Subaru Vehicle Speed Sensors (VSS) Part 3 - Extension Harness Differences for 3-Wire VSS Types

Subaru Vehicle Speed Sensors (VSS) Part 3 - Extension Harness Differences for 3-Wire VSS Types

Mar 28, '24

In this blog post we talk about the jumper harness on your Subaru transmission’s Vehicle Speed Sensor (VSS). This applies to 99-07 Subaru models with a 3-wire VSS. 

Click here to learn more about VSS Sensor Types of all years  

Types of VSS Connections

All of the vehicle speed sensors on Non Turbo (NA), Turbo (non DCCD), and DCCD transmissions have a three pin single row connection (pictured below). However on NA (e.g. Impreza) and Turbo (WRX) models there is an adapter harness or jumper that runs from the sensor itself on the transmission to the bulkhead (body) wiring harness. Even though the sensor connection is the same, the jumper may have different connectors.  

(If you transmission doesn't have a built in speed sensor, click here to learn more)


Non Turbo Cars – Jumper harness is a 3 pin single row connector to a 3 pin single row connector. This is basically just an extension to make the wiring reach in the car better

Turbo Cars (Non DCCD) – Jumper harness is a 3 pin single row connector on the transmission to a 4 pin square connector that only has three wires in it. This 4 pin connector plugs into the body wiring of the car

DCCD Cars – No jumper harness at all

So why does this jumper harness matter?

  1. The jumper harness has two functions – it extends the wiring from the vehicle speed sensor to make it easier for servicing and repair and it also has a protective jacket on that wiring to protect it from the heat and abrasion of the transmission.
  2. If your car is missing the jumper harness we recommend purchasing one of our replacements below.
  3. When we sell the iWire VSSPro Controller we make it plug into the car wiring so you don’t have to crimp, cut or splice. Our kit is designed to plug into the main body harness and not the jumper so it may come with a 3-pin single row connector or a 4-pin square connector. 


iWire Recommendations:

VSSPro Controller Installation - Remove Factory Jumper 
Remove this jumper harness from the transmission and plug the VSSPro wiring harness directly into your bulkhead wiring harness.

NA to Turbo or Turbo to NA transmission swap - VSS Replacement Harness
We recommend purchasing one of our VSS Replacements to make sure the VSS gets plugged into the bulkhead wiring harness.

NA to DCCD or Turbo to DCCD transmission swap - VSS Extension Harness
With the DCCD transmission the VSS is placed closed to the main body harness so the factory jumper will be overly long. Our VSS Extension harness will get the length and/or conversion harness you need and keep the engine bay tidy.

Use the links below to learn more or purchase one of our items mentioned in this blog. 

iWire VSS Extension

iWire VSS Replacement Harness

iWire Plug and Play VSSPro Controller

VSS and your Transmission Swap Blog Post