Haltech Nexus S2 pinout and specs

Checked against the maker's documents 27 September 2026

Haltech Nexus S2 is a 60-pin wire-in Haltech ECU on 2 connectors: A (26 pins) and C (34 pins).

It has 4 injector outputs and 4 ignition outputs. The injector drivers are peak-and-hold, so low-impedance injectors run without a resistor pack. The ignition outputs are logic-level. Smart coils plug straight in; dumb coils need an igniter in between.

There are 2 dedicated trigger inputs, each happy with a VR or a Hall sensor. Two knock inputs cover both banks of a V engine. It has an onboard wideband controller, so a sensor wires straight in. The MAP sensor is built in.

Drive-by-wire is native: 2 throttles from its own H-bridge outputs. Two CAN buses handle dashes, PDMs and expansion. Four outputs can switch 12V as well as ground. The maker rates the 5V sensor supply at 200 mA in total.

Spec sheet

Which builds it suits

Of the 58 swap presets in the planner, 6 fit as they are and 8 fit with add-ons; 44 do not fit at all. The add-on it asks for most often is the Haltech WB1 (single-channel CAN wideband). Where it falls short, it is usually not enough injector output (low-side). The planner fills anything a preset leaves open with its ordinary defaults, so your own build may land differently.

It runs the Honda K20 (i-VTEC 2.0 NA), Mazda Rotary 13B-REW (FD RX-7) and Mazda Rotary 13B-MSP Renesis (RX-8 auto, 4-injector) presets with nothing added. The Nissan SR20DET (S14) needs Haltech HPI8 High Power Igniter (8-channel). The Subaru EJ/FA EJ25 turbo dual-AVCS (EJ257 2008+) needs Haltech WB1 (single-channel CAN wideband). It can't run the GM LS LQ4/LQ9 (Gen3 6.0 iron): not enough injector output (low-side). It can't run the Ford Modular 5.4 4V Ford GT (S/C, cable): not enough injector output (low-side). It can't run the Nissan VQ35HR (High-Rev, 2007+): not enough injector output (low-side).

Plan a build around the Haltech Nexus S2

Pin table

By connector: A carries 4 injector outputs, 4 ignition outputs and 6 digital inputs; C carries 2 trigger inputs, 2 knock inputs and 11 analog inputs.

Other Haltech ECUs

The closest Haltech unit is the Haltech Elite 1500. Against it, this one has 2 knock inputs (the Elite 1500 has 1), 1 wideband controller (the Elite 1500 has 0), 60 pins (the Elite 1500 has 53) and 2 drive-by-wire channels (the Elite 1500 has 1).

• Haltech Elite 1500
• Haltech Nexus S3
• Haltech Nexus T1
• Haltech Elite 2500

Source: Haltech documentation for the Nexus S2

Always verify against the manufacturer's manual and your tuner before wiring.