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Subaru Harness Information

This page shows information on early and later model CANBUS Subaru harnesses using the standard Subaru engine management.

The electrical components you need.

How to remove the harness components from a donor vehicle.

The loom modification process from the entire harness to the finished product.

Harness examples for a range of models including the EJ, EZ, FA and FB engines. Australian, General Market and USA models.

Information on the Subaru Interface box and the advantages with late model harnesses.

EZ30R Harness Example (Gen4 04-09 Liberty-Legacy-Outback)

The Gen4 Liberty-Legacy-Outback was the first Subaru model to introduce Canbus and electronic (DBW) throttle control. The early models (~04-06 pre facelift) only had a few signals over Canbus, in fact in most cases the engine ECU will run satisfactorily without any form of Canbus emulator. A Canbus Emulator is recommended however, as the emulator is the only method to add a vehicle speed signal to the engine ECU. The speed signal can improve the drivability, and is required if you want cruise control.

Discrete wiring for Oil Pressure, Charge Lamp, Tacho and Check Engine (MIL) lamp is the same as pre Canbus harnesses and dash indication can be interfaced to old fashioned lamps and gauges. The exception to this is the temperature gauge, as this signal is sent via Canbus from the engine ECU to the Cluster. If you want a coolant temperature gauge, you will need to add a temperature sender to the coolant lines.

The main complexity with the Canbus harnesses is not actually the Canbus, but the more complicated immobiliser system. In this model, the cluster also plays a role in the immobiliser system. The components required for the immobiliser system include the following:


BODY COMPUTER (BIU) (only 10-12 wires need to be retained)

KEY AND BARREL (2wire antenna)

DASH CLUSTER (only 5 wires need to be retained)

All of the above components need to be obtained from the same vehicle to make sure they all match.

Although the cluster can be removed with our "dash cluster delete module", the cluster from the donor does need to be available initially to copy the immobiliser codes to the cluster delete module.

Some advantages of the Gen4 Engine control system include:

Smoother operation and idling with the DBW system

Easier to adopt cruise control (Just need the buttons, brake switch and Canbus Emulator)

Better OBDII support (especially later 06+ models that have OBDII over Canbus)

Tap shift (sport shift) manual control ability of the automatic transmission

In some cases LESS wiring (particularly ECU to the TCU automatic transmission)


The video below describes the EZ30R system, harness removal from the donor, wiring harness modification process, through to the stand alone test running of the engine.

EZ30R into VW T3 Van (loom by AGT installed by customer)

EZ36 Harness Example (2010 USDM Tribeca)

The 6 Cylinder 3.6L EZ36 was Subaru's largest engine. First appearing in the Subaru Tribeca and Gen5 Liberty-Legacy-Outback. The Tribeca harness is very similar to the gen4 Liberty-Legacy-Outback, which is described above. Using the Subaru OEM harness and ECU is relatively straight forward for this model with the required knowledge.

The pictures below show an unmodified USA sourced (USDM) harness and the required components, through to the final completed harness. The harness consists of the main (body) harness shown at the bottom of the picture and the dash harness, shown above. The BLUE line differentiates the two harnesses.

Only two plugs are needed from the dash harness, the cluster plug and the 3rd BIU plug. Only a few wires are required to each plug, so 95% of the dash harness is discded.

The video shows the late stages of the harness modification and testing of the USDM harness on an Australian EZ36 Engine (From gen5 Outback)


This is what is sent for harness modification for stand-alone


Approximate cost for above harness modification (including Canbus Emulator and Interface box)  $1200USD * as of OCT2022

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