This iWire blog post breaks down some basic harness terminology. We hope these diagrams will make it clear exactly which harness is which and the harnesses needed to complete your merge.
Subarus are a bit different from most cars. With most manufacturers the ECU to engine wiring harness is all one harness called the engine harness. With Subaru, the engine harness is what is physically on the engine (think intake manifold harness). The Subaru engine harness plugs into the bulkhead harness which runs to the body side of the car in the engine bay that works into the cabin and connects to the ECU.
Please note that all of these harnesses unplug from each other. They do not need to be cut to remove them. Just keep following the wires until everything is unplugged and then the harness can be easily removed. This may mean removing the dash bar, blower box, etc. to get access to all of the plugs.
Where do the Harnesses Connect to Each Other?
- The bulkhead harness can be separated from the engine harness in the engine bay near the engine.
- The bulkhead harness can be separated from the front harness typically inside the cabin near the fuse box.
- The bulkhead harness can be separated from the rear harness depending on the car year. For older cars, the bulkhead and rear harnesses meet by the driver side front door. For new cars, the bulkhead and rear harnesses meet underneath the passenger side front seat.
For iWire to do a Merge We Need:
For most cars we need the bulkhead harness in compartment and bulkhead harness in engine bay from the chassis car you plan to use. We also need the bulkhead harness in compartment, bulkhead harness in engine bay, and front harness that matches the engine or drivetrain you plan to use. The bulkhead harness in compartment and bulkhead harness in engine bay are actually one very large harness. Please note we do not need any rear harnesses for our merges. Please leave these plugged in.