Using the Chevy Vortec ignition module

A basic ignition module

While some MegaSquirt versions have ignition modules built in, many versions do not, including the MicroSquirt, wire-in MS3Pros, and many others. These have 5 volt logic level spark outputs instead. If you need to run a distributorless ignition where the coils need an external ignition module, our QuadSpark is a great option. If you need a high performance distributor to run a turbo motor or a high revving V8, there are many capacitive discharge ignition (CDI) systems to give a hot spark that won’t drop off at high RPM.

But what if you need just one spark output, and your main goal is to have a robust module that you can find a replacement for in any parts store in North America? In this case, if there wasn’t a suitable module on your car to begin with, a cost effective option is the ignition module that General Motors used on the ’96-’00 pickup trucks with the 350 Vortec. Here are some of the part numbers for the factory module and common service replacements.

  • AC Delco D579
  • Delphi DS10039
  • Airtex / Wells 6H1051
  • Standard Motor Products LX381

If you find one in a wrecking yard, these come with a heat sink in factory applications, and have a mounting bracket that allows you to use it with GM’s factory coil. You can, however, use it with other coils as well – this is a fairly basic module, not one that performs VR conditioning or active dwell control.

As is often the case with GM connectors, you can identify the pins by tiny letters cast into the matching connector (GM part number 12162189).

  • A: Switched 12 volt power
  • B: Ignition signal from MegaSquirt
  • C: Ground to cylinder head
  • D: Coil negative terminal

This module does not control dwell. If you have a good spec sheet for your coil, see the MegaManual dwell calculator and use 8.0 amps for the maximum current. (The actual maximum current may depend on the brand of module, but this is typically a safe number.) If you are using a stock type coil and cannot find these specs, 2.5 ms dwell time is usually a safe number.

MicroSquirt wiring and settings

For this ECU, you’ll run the wire from pin 12 (IGN1) to the B pin on the ignition module. Use these settings for MS2/Extra. These only include the settings specific to the module – other settings such as spark mode will depend on the trigger wheel used and the coil.

  • Spark output: Going high
  • Spark A output pin: IGN1
  • Dwell type: Standard dwell

Use these settings for Bowling & Grippo code.

  • Coil charging scheme: Standard coil charge
  • Spark output: Going high (inverted)

MS3X wiring and settings

For an MS3 V3.0 or V3.57 with MS3X, use the Spark A output on the MS3X board (pin 14). Use these settings in TunerStudio.


  • Spark output: Going high
  • Spark hardware in use:  MS3X spark
  • Dwell type: Standard dwell

MS3Pro wiring and settings

These apply to the first generation MS3Pro, MS3Pro Ultimate, and MS3Pro EVO. Connect the Spark A output wire, pin 27 on the gray AMPSEAL, to pin B of the ignition module. Use the following TunerStudio settings.

  • Spark output: Going high
  • Spark hardware in use:  Spark
  • Dwell type: Standard dwell

This does not apply to the MSPNP Pro units. Plug and play variants are designed for using the standard ignition module for their intended application, or have internal ignition modules if the application requires.