Haltech Nexus S3 pinout and specs

Checked against the maker's documents 27 September 2026

Haltech Nexus S3 is a 68-pin wire-in Haltech ECU on 2 connectors: A (34 pins) and C (34 pins).

It has 8 injector outputs and 8 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, 10 fit as they are and 47 fit with add-ons; 1 does 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 knock inputs. The planner fills anything a preset leaves open with its ordinary defaults, so your own build may land differently.

It runs the Nissan RB26DETT (R34, smart coils), Honda K24 (i-VTEC 2.4 NA) and Mazda Rotary 13B-MSP Renesis (RX-8 auto, 4-injector) presets with nothing added. The GM LS L92 (Gen4 6.2 alum) needs Haltech WB1 (single-channel CAN wideband). The Nissan VQ35DE Rev-Up (2005-06) needs Haltech WB1 (single-channel CAN wideband). It can't run the BMW S54 (3.2 NA I6, E46 M3): not enough knock inputs.

Plan a build around the Haltech Nexus S3

Pin table

By connector: A carries 8 injector outputs, 8 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 Nexus R3 VCU. Against it, this one has 68 pins (the Nexus R3 VCU has 72).

• Haltech Nexus R3 VCU
• Haltech Elite 2500
• Haltech Nexus S2
• Haltech Elite 2000

Source: Haltech documentation for the Nexus S3

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