Upgrade Your Nissan S14 240sx with a High-Performance RB25DET NEO OBDII Wiring Harness

For enthusiasts looking to maximize the potential of their USDM S14 240sx with an RB25DET NEO engine swap, the Rb25det Neo Obdii wiring harness is a critical component. Electrical gremlins and unreliable connections can plague engine swaps, but with the right harness, you can achieve a clean, dependable, and high-performing setup. This Pro Series harness is engineered to completely replace your old OEM harness, delivering superior aesthetics, significant weight savings, and unmatched reliability for your project.

Why Choose the Pro Series RB25DET NEO OBDII Harness?

This Wiring Specialties Pro Series harness is meticulously designed to not only meet but exceed OEM standards. From wire quality to power and ground routing, every aspect is optimized for peak performance and longevity. The ‘tucked’ and streamlined design results in a visually appealing engine bay and, more importantly, a worry-free installation that ensures your RB25DET NEO engine starts reliably every time.

Specifically tailored for the USDM S14 240sx chassis and the RB25DET NEO engine, this harness is the plug-and-play solution you’ve been searching for. Developed in-house on a real RB25DET NEO engine, it guarantees a perfect fit for all engine connections, eliminating guesswork and potential headaches during your swap. Whether your S14 is an OBDI or OBDII model, this harness is designed for seamless integration.

RB25DET NEO OBDII Engine and S14 240sx Chassis Compatibility

This harness is designed for direct compatibility with the following engine and chassis combinations:

ENGINE: RB25DET NEO

• All RB25DET NEO variants from R34 Skyline GTS/GTST models manufactured between 1998 and 2002.
• All RB25DET NEO variants from WGNC34 Nissan Stagea models.

CHASSIS: LHD USDM S14 240sx

• Compatible with all USDM LHD S14 240SX models from 1995 to 1998, including both OBDI and OBDII equipped vehicles.
• For factory tachometer functionality when changing cylinder counts, manual tach adjustment via potentiometer is required.
• Maintaining factory speedometer functionality necessitates the use of the original factory speed sensor in your new transmission setup.
• Essential functionalities like reverse lights, wipers, alternator warning light, and oil pressure warning light are preserved with this harness.

Pro-Series Harness Technical Specifications for RB25DET NEO OBDII

This harness is built with high-quality components and rigorous testing to ensure optimal performance and reliability:

• Plug and Play Design: Simple and efficient installation with no cutting or splicing required.
• No Core Harness Required: Eliminates the need for sending in your old harness or dealing with core charges.
• OEM Wire Colors: Utilizes OEM wire colors where applicable for easy identification and maintenance.
• EM Shielded Sensor Wires: All sensor signal connections are made with EM shielded wires to minimize interference and ensure accurate readings.
• Fireproof Fiberglass Sleeving: High-temperature areas near the manifold and turbo are protected with fireproof fiberglass sleeving, capable of withstanding temperatures from -40°C/-40°F to +450°C/+845°F.
• Point-to-Point Continuity Tested: Every wire is individually tested for continuity to guarantee electrical integrity.
• OEM Connectors and Seals: Constructed using exact OEM connectors and seals for a secure and weather-tight fit.
• High Temp TXL Wire: Made with high temp TXL wire and adhesive shrink tubing, operating reliably from -40°C/-40°F to +125°C/+257°F.
• Lightweight Nylon Loom: Wrapped in lightweight nylon loom, offering protection from -94°C/-137°F to +125°C/+257°F.
• Improved Grounds and Charge Harness: Includes a charge harness and enhanced grounding for optimal electrical performance.
• Fully Tested Production: Each harness is thoroughly tested after production to ensure an easy plug-and-play installation and guaranteed engine start.

What’s Included in the Pro-Series RB25DET NEO OBDII Harness Kit?

The Pro-Series Harness kit provides everything needed for a complete and professional installation:

• One-piece tucked harness for the main engine and transmission.
• Alternator charge cable for improved power routing.
• 6x Coilpack connections specifically designed for NEO engines.
• 6x Injector connections for precise fuel delivery.
• 2x Knock sensor connectors for engine protection.
• MAFS connectors (Note: S2/NEO OEM MAFS compatible).
• TPS (Throttle Position Sensor) connector.
• Boost solenoid wiring with OEM connector for boost control.
• Boost sensor connector for accurate boost readings.
• VTC (Variable Valve Timing Control) connector.
• Cam sensor connector for camshaft position sensing.
• Crank sensor connector for crankshaft position sensing.
• Idle air and fast idle connections for proper idle control.
• OEM Oxygen sensor connectors (wideband wiring is not included in the EFI harness, except for AEM Infinity 6/8 systems).
• 2x Ground ring terminals for secure grounding points.
• Air regulator connector (located under the intake manifold).
• ECT (Engine Coolant Temperature) sensor connector and cluster coolant temp switch connector.
• Reverse lights sensor connector for functional reverse lights.
• Speed sensor connector for speedometer operation.
• Alternator connector for alternator integration.
• Starter signal connector for starter engagement.
• OEM oil pressure 2-pin connector (only 2-pin version supplied).
• Nissan ECU Diagnostics mode connector for easy diagnostics.
• Dash and fuse box connections via the Interface harness.
• Printable install instructions with detailed pictures for easy setup.
• Turn Key ENGINE START Guarantee for peace of mind.
• 7 days a week tech support for customer assistance.

Aftermarket ECU Compatibility with your RB25DET NEO OBDII Harness

For those seeking even greater control and performance, this Pro Series harness can be customized to work seamlessly with aftermarket ECUs.

• Customization Options: Wiring Specialties offers customization to ensure your PRO harness fits your exact build requirements with aftermarket ECUs. A downloadable ECU/Build details form is available for submission with your order to specify your needs.
• Wideband O2 Sensor Support: AEM Infinity, Link, and ECU Masters products (among others) can process wideband signal input directly. For these systems, the LSU 4.2 version of the WB O2 Sensor is recommended. Options for Oval or Rectangular connectors are available to match your WB O2 sensor.
• ECUs without Direct Wideband Processing: For ECUs that cannot directly process wideband signals, the harness is wired for a FACTORY O2 sensor, and a labeled flying lead is provided for connecting the ECU to a Wideband controller (like AEM UEGO Gauge Kit or Haltech CAN wideband unit).
• Pre-wired Sensors for Advanced ECUs: Harnesses for AEM Infinity, Motec, Link, and ECU Masters are pre-wired for direct Oil Pressure, Fuel pressure, Oil Temp, IAT, and MAP sensor wiring to the ECU. Flex Fuel support and ECU control of a Boost Control Solenoid are also available on most harnesses.
• Apex’i PFC Considerations: Apex’i PFC conversions include the IAT sensor in the main harness, while the MAP sensor is wired separately. The MAP sensor harness should be purchased with the PFC.

FAQ & Other Important Details for RB25DET NEO OBDII Harness Users

• Alternator Charge Cable: Improves power routing by directly connecting the starter/battery to the alternator output, eliminating the traditional wire run to the fusebox or battery.
• ECU Patch Harness (Optional): Avoid cutting into your engine harness for accessories. This optional item provides a length of wire between the harness plug and ECU for easy installation of air-fuel meters, boost controllers, and more.
• Grounding Kit (Optional): Ensures optimal grounding by connecting engine components to the car body, eliminating potential ground-related issues. Utilizes ultra-high temp fiberglass sleeving for installation near exhaust components.
• Speedo / Tach Signal Conditioning (Optional): Dakota Digital SGI-5 (Speed) and SGI-8 (Tach) units can be added to compensate for cross-platform swaps or changes in cylinder counts, ensuring accurate gauge readings.
• Plug-n-Play vs Universal: This Pro-Series harness is Plug-n-Play, connecting to your car’s underhood fuse box and under-dash connectors for gauges. Universal harnesses have ‘flying leads’ for gauges and warning lights and do not require fuse box connections.
• Right Hand Drive (RHD) Conversions: Harness selection depends on the chassis connectors used during your RHD swap. Contact us for modifications if a mix of LHD and RHD connectors were used.
• Don’t See Your Option? Contact us for custom options regarding injectors, throttle bodies, coilpacks, or other components.
• Battery Cables / Battery Relocation: Ensure proper battery cable connection from the positive terminal to the starter main power lug, as this cable also powers the under-hood fuse box.
• LS2/LQ9 GM V8 Coil Pack Conversions (Optional): Upgrade to high-performance and readily available LS2/LQ9 Smart Coils. Eliminates the ignitor chip and uses mounting kits (MOJO Performance) for easy installation on JZ or RB engines.

Upgrade your RB25DET NEO OBDII engine swap in your S14 240sx with the Wiring Specialties Pro Series harness and experience the difference in quality, reliability, and performance.