Rywire L15B7 Swap Engine Harness - 1.5L Turbo Civic Si Computer, Tefzel Tucked (L15B7-Base)

Rywire L15B7-Base is a complete L15B7 swap engine harness for the Honda 1.5L turbo L-series, running the factory Civic Si engine computer with FlashPro. It replaces the factory harness entirely, moves the computer and fuse box out of the engine bay into the passenger footwell, and connects to your car through a Rywire chassis-specific adapter. Built with all-black Tefzel wire in high-heat expandable loom with white ID labels.

Why This L15B7 Swap Harness for Your Honda Build

Rywire L15B7-Base is a complete L15B7 swap harness that runs the factory Civic Si computer with FlashPro and moves the computer and fuse box from the engine bay to the passenger footwell.

• Versus adapting the factory Civic Si harness: This Rywire L15B7 harness is a full replacement, not a factory-harness adapter. It connects to your chassis through a Rywire chassis-specific adapter instead of spliced body plugs.
• Versus a used donor harness: Donor harnesses are often cut at the body plugs or missing plugs. This Rywire L15B7 harness is built from all-black Tefzel wire in high-heat expandable loom with white ID labels.
• Versus a universal flying-lead harness: This Rywire L15B7 harness arrives terminated for the direct injection pump, four direct injectors, drive-by-wire throttle and pedal, both cam sensors and VTC solenoids, wastegate and battery current sensor.
• Computer out of the heat: This Rywire L15B7 harness passes through the passenger-side firewall so the computer and fuse box mount in the cabin, away from engine-bay heat.
• Chassis coverage: This Rywire L15B7 harness has adapters for 1988-2000 Civic, 1988-1991 CRX, 1990-2001 Integra, 2002-2004 RSX/EP3, 1999-2006 Insight (core required) and RX-7 FD3S, plus race options.

Best for: 2017-2021 L15B7 1.5L turbo swaps on a factory Civic Si computer (37820-5AM-A03 to A05) with FlashPro. Integrating it yourself: choose Mating Connector Only.

Engine Swap Fitment

• Honda L15B7 1.5L turbo engines, 2017-2021
• Civic Si engine computers 37820-5AM-A03 through 37820-5AM-A05 with FlashPro
• Chassis adapters for 1988-2000 Civic, 1988-1991 CRX, 1990-2001 Integra, 2002-2004 RSX/EP3 Civic, 1999-2006 Insight and Mazda RX-7 FD3S
• Any other chassis through the Other/Custom/Race-Style adapter, the Rywire Race Fuse/Relay Box V3 or the Rywire PDM chassis harness

Features

• Full replacement harness, not a factory-harness adapter
• All-black Tefzel wire in high-heat expandable loom
• White tag labels for easy installation and service
• Runs through the firewall on the passenger side; Rywire recommends mounting the computer in the cabin near the passenger feet
• Engine computer and fuse box moved out of the engine bay, away from heat
• Prewired for the Rywire Drive By Wire Pedal Kit

Connector List

• Engine computer plugs A and B
• Drive-by-wire throttle body
• Drive-by-wire pedal (Rywire DBW pedal kit)
• Crankshaft sensor
• Intake and exhaust cam sensors
• Intake and exhaust VTC solenoids
• MAF/temperature sensor
• Coolant temperature
• Intake air temperature and IAT 2
• A/C
• Coil packs 1-4
• Direct injection pump
• Four direct injectors
• Reverse lockout
• Knock sensor
• Alternator
• Reverse lamps
• Starter motor
• Narrowband and wideband oxygen sensors
• Oil
• Wastegate
• Battery current sensor
• Grounds for head and computer
• Fuse box for computer and injector power
• Additional factory circuits labeled NC, IPV, PF, ABV, NTRL and Trans

Choosing Options

• Vehicle: your chassis, which sets the chassis adapter Rywire builds. Choose Other/Custom/Race-Style, Race Fuse/Relay Box V3 (with or without Switch Panel) or Rywire PDM System for race cars and unlisted chassis, or Mating Connector Only to integrate it yourself. The 1999-2006 Insight adapter requires a core.

What's Included

• L15B7 swap engine harness, all sensors prewired for OEM components
• Chassis adapter (or race fuse/relay box option) for the vehicle you select
• Fuse box for computer and injector power

Frequently Asked Questions

Which engine computer does it use?

The factory Civic Si computer with FlashPro. Computers 37820-5AM-A03 through 37820-5AM-A05 should be usable.

My chassis is not listed. Can I still use it?

Yes. Choose Other/Custom/Race-Style, the Rywire Race Fuse/Relay Box V3 or the Rywire PDM chassis harness, or email us and we will check with Rywire.

Does it work with a drive-by-wire pedal?

Yes. It is prewired for the Rywire Drive By Wire Pedal Kit (DBW-PEDAL-KIT-EG). Email service@tunedbyshawn.com with your engine, chassis and ECU before ordering if you are unsure which configuration you need.

Should I adapt the factory Civic Si harness or buy a Rywire L15B7 swap harness?

The Rywire L15B7-Base replaces the factory harness entirely, keeps the factory Civic Si computer with FlashPro, and moves the computer and fuse box to the passenger footwell. It connects to your car through a Rywire chassis adapter, so no factory body plugs need splicing.

For off-road and competition use only. Not legal for use on pollution-controlled motor vehicles.