ICT Billet 96in Resistor Pigtail for LS Gen III 4‑pin Alternator — 105A, OEM‑grade TXL 8ft lead

ICT Billet's 96-inch resistor pigtail converts a 12V feed into the correct alternator "on" signal for 4-pin LS Gen III alternators, enabling a 105A alternator to work without an ECM reference.

If you've swapped an LS Gen III engine or fitted a standalone charging system, the alternator's "on" terminal often expects a lower signal voltage than an unmodified 12V source. This assembled-in-USA pigtail contains an inline resistor and high-quality TXL wire to condition the feed so the 4-pin flat connector on GM-style alternators recognizes the turn-on signal. Built by ICT Billet in Wichita, Kansas, the product is intended for 1999-and-newer GM LS series engines and specifically supports the 105 amp WPALT31 alternator when an ECM reference is absent.

How does this resistor pigtail make an alternator work without the ECM?

The pigtail contains an inline resistor that reduces the raw 12V input to the alternator's required "on" signal voltage. By matching the expected voltage and current characteristics, the alternator's internal control sees a proper start command even when the engine control module is not present or not providing the 5V reference.

• Includes a built-in resistor sized for LS Gen III 4-pin flat alternator inputs
• Pre-assembled 96" (8 ft) lead for flexible routing in engine bays
• Compatible with alternators that expect a lower-than-battery-voltage signal

Which engines and alternators are compatible with this pigtail?

This wiring pigtail is designed for GM's LS-series (1999 and newer) Gen III engines that use the 4-terminal flat alternator connector. It allows the use of a 105 amp WPALT31 alternator when the vehicle lacks the ECM's 5V reference or when using custom engine management.

• Works with 4-pin flat connectors found on many GM LS alternators
• Validated for the 105A WPALT31 alternator model
• Suitable for swaps, hot-rods, or vehicles running standalone controllers

What materials and build quality does ICT Billet use?

Each pigtail is assembled in Wichita, Kansas using OEM-grade TXL wire manufactured in the United States. The construction focuses on durable insulation and reliable crimps to withstand under-hood temperatures and vibration typical of performance and street builds.

• Assembled in the USA for quality control and traceability
• OEM-grade TXL wiring for heat and abrasion resistance
• Factory-style connector fit for a secure alternator plug-in

How long is the pigtail and how does that affect installation?

The product ships with a 96" total length that includes a 72" usable lead from the connector, giving ample slack to route around headers, fuse blocks, or firewall bulkheads. The extended length simplifies placement in engine swaps and custom installations where original harness routing is not available.

• 96" overall length with 72" of wire lead for flexible routing
• Reduces need for additional splices or extensions
• Saves installation time in tight or custom engine bays

Who is this for: This pigtail is aimed at technicians, hot-rod builders, engine swap hobbyists, and anyone installing GM LS Gen III engines or a 105A WPALT31 alternator without relying on the OEM ECM signal. If you need a plug-and-play style resistor solution built from quality TXL wire and assembled in the USA, this ICT Billet pigtail provides a practical, OEM-compatible way to get your alternator to recognize the "on" command.