Honda K-Series / Mazda Miata 31-Way ECU Connector Plug Kit

OEM-Style 31-Pin ECU Connector for K-Series & NB Miata Applications

The 31-Way ECU Plug Connector Kit is an OEM-style replacement connector used in Honda K-Series ECU systems and select NB Mazda Miata ECU applications. This 31-pin connector is commonly required for ECU repairs, standalone conversions, and professional custom harness fabrication.

Designed for serious wiring projects, this connector provides correct pin alignment, secure terminal retention, and long-term electrical reliability for high-performance and motorsport environments.

Ideal for Standalone ECU Builds & Harness Fabrication

ECU connector damage from corrosion, broken locks, or previous wiring modifications can lead to intermittent faults and unreliable communication. Replacing the ECU plug with a proper OEM-style housing restores signal integrity and ensures a secure interface between the harness and ECU.

This connector kit is commonly used for:

• Honda K-Series ECU harness repair

• NB Mazda Miata ECU connector replacement

• Standalone ECU adapter harness builds

• Custom jumper or extension harness fabrication

• Motorsport and race vehicle wiring projects

OEM-Style Construction with Proper Terminal Retention

The 31-pin housing is manufactured to OEM-style specifications, ensuring proper fitment and terminal engagement when correctly crimped and installed. When paired with professional open-barrel crimping tools, this connector delivers consistent electrical contact suitable for engine management systems.

This connector is equivalent to:

• Toyota 90980-11421

• Toyota 90980-11935

Cross-referencing expands compatibility across multiple OEM and custom applications.

Cross-Platform Compatibility

Common applications include:

• Honda K20 / K24 ECU configurations

• NB Mazda Miata ECU setups

• Toyota-based connector cross-reference applications using 90980-11421 or 90980-11935

Always confirm connector keying and cavity layout before installation, as ECU variants may differ by year and model.

What’s Included

• 1× 31-Way ECU Connector Housing

• Matching Terminals

• Seals (where applicable)

This kit includes the necessary terminals and components to integrate directly into custom or replacement wiring applications.

Installation Notes

Professional wiring knowledge is recommended. Proper depinning and crimping tools are required to ensure secure terminal installation and long-term reliability.

Fitment may vary depending on ECU version and harness configuration. Minor adaptation may be required in certain standalone or conversion builds.