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Custom Harness ULTIMATE + GM Gen4 LS W/Bosch EV6 EV14 DIYAutoTune




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This product is for Racing Competition only and is not legal for use in highway or street vehicles or other non-racing competition off-road vehicles.

Purchasing this product requires you to sign our Vehicle Compliance Waiver here.

Durable, custom harness with factory coil, sensor, power, ground and starter terminations for a General Motors Gen 4 LS motor with 58x crank sensor. Integrated Fuse and Relay Control Module Fuel Injector Branchesequipped with Bosch EV6/EV14 style connectors.

Professionally engineered and easy to install, fire up your engine on day one! All wiring is composed of TechFlex woven, self-extinguishing wrapped hi-temp TXL and GXL automotive grade wire with OEM Delphi and TE connectors. Reach the battery under the hood or in the trunk with 4 gauge power and 10 gauge ground wires.

All relays and fusing live in a single, waterproof fusebox and the fuel pump wiring / relays / fusing is big enough for pumps that can handle 1000whp or more right out of the box (10ga wire, 30amp circuit).

Additionally, all of the available I/O of the MS3Pro are brought out in the harness to make expansion as easy as possible regardless of the featureset you're planning to use, allowing for killer features like traction control, bump box, table switching, flex fuel, and more. This harness was designed to add optional 4L60E or 4L80E automatic transmission control as a plug and play extension (add PN: MS3PH-TRANS_4L60-PKG or MS3PH-TRANS_4L80-PKG)
MS3Pro ULTIMATE GM LS 58x Plug and Play includes

  • TunerStudio software suite (installed/ copy on included 8GB flash drive)
  • USB and Serial communication cables
  • GM Gen 4 LS base tune(s)
  • Durable, custom harness with factory coil, sensor, power, ground and starter terminations for a General Motors Gen 4 LS motor with 58x crank sensor
  • Integrated Fuse and Relay Control Module
  • Fuel Injector Branches equipped with Bosch EV6/EV14 style connectors.

Required connections:

  • Constant Power
  • Constant Ground
  • Switched Power
  • Starter
  • Alternator light
  • Suggested extra connections:
  • Fuel Pump Power
  • Tachometer Signal

The custom MS3Pro 58x GM LS Plug and Play Harness is configured for a cable operated throttle body. The included connectors are set up for an LS1 style throttle position sensor and IAC valve. Four barrel style or independent throttle body setups may require modifications to the harness.

Note that the alternator connection is designed for high mount alternators such as Corvette and truck setups. Low mount alternator setups, as well as other aftermarket accessory drives that do not have the alternator high on the driver's side, require our alternator extension cable (MS3Ph-LSAlt).

Proposition 65

/!\ warningWARNING: Cancer and Reproductive Harm

Who is DIY AutoTune?

DIYAutoTune is a company that Jerry Hoffmann founded in 2004. What started as a hobby became a booming business. The company specializes in producing the latest tuning products and kits. Today, they have become one of the leading companies in their market segment.

EMS Expert

They have everything you need to install a fully programmable Engine Management System on any vehicle, whether a truck, car, motorcycle, utility vehicle or even boat. The company offers various tuning products from the MegaSquirt line of DIY Programmable Electronic Fuel Injection systems, MegaSquirt wiring harness, Innovate Motorsports LC-1, and LM-1 Wideband O2 Sensor systems and gauges, and ignition components. 

Wide Range of Products

When it comes to Engine Management systems, DIY AutoTune is the brand to go to. They also have ready-to-install kits for enthusiasts who want a plug-and-play product. Whatever route you choose, they guarantee to provide total control and tunability of your engine, allowing you to extract maximum power every time.

Purchase DIY AutoTune At Vivid Racing

Today’s modern engine requires special equipment for you to tune it base on your liking. If you are in the market for a product that would allow you to be in control, then look no further as DIY AutoTune is the brand for you. All their electronics are labeled clearly and have everything you need for the install. 

To know more about DIY AutoTune and what they can offer, visit Vivid Racing and check out their list of products that fit your specific requirement.

Warranty Information - DIYAutoTune Un-Assembled Kits

Products purchased in kit form we will guarantee have all parts needed to complete the kit, and the parts will be in new and working condition when we ship them to you. If you find a discrepancy please notify us. We're pretty easy to work with and we'll do our best to take care of you quickly. Obviously we cannot warranty your assembly work of a kit. If you get stuck we suggest posting a thread at or and emailing us the link so we can attempt to chime in and working together with others we can usually help you get to the root of your problem. That being said most people don't have any problems assembling our kits, they are clearly labeled and go together just about as easy as any kit could.

Warranty Information - DIYAutoTune Assembled MegaSquirt ECUs and Accessories

This section applies to any product that is available as a kit, but that we also offer as an assembled product. Examples would be standard MegaSquirt I and II ECUs, Stimulators, and the like. Standard off-the-shelf MegaSquirt ECU Assembled units are covered by a one year limited warranty against manufacturers defects. Contact us if you believe you have an issue that should be covered under warranty. We will discuss the issue with you and provide an RMA number and an address to ship your unit to. Our tech will evaluate the unit and if a problem due to manufacturer defect is found we will repair it free of charge. We will cover the cost of shipping from our shop to you up to $25; we will need for you to cover any cost of shipping beyond $25 and the cost of shipping the unit from your location to our shop. If we determine that the problem was due to mis-use, mis-installation or improper modification, our shop rate will be $75/hr plus materials to repair your unit (one hour minimum).

We do not mind the modification of the unit as that's the spirit of the MegaSquirt project, just understand that if your mod appears to be the likely culprit of damage to the unit that we cannot support the unit under warranty. Note that extensive modification may complicate the troubleshooting process, and in some cases it may be neccesary to reverse modifications in order to return the unit to working order. Charges will apply for the time required, and in these case we cannot be responsible for putting custom modifications back in place after having to remove them to resolve a problem.

Warranty Information - Manufactured Products

General Indemnity
Race parts are inherently dangerous in general and may cause injury or damage if improperly modified or altered before use. Hoffmann Innovations will not be held liable for and will not pay you for any injuries or damage caused by misuse, modification, redesign, or alternation of any of our products. Hoffmann Innovations will not be held in any way responsible for any incidental or consequential damages including direct or indirect labor, towing, lodging, garage, repair, medical, or legal expense in any way attributable to the use of any item in our catalog or to the delay or inconvenience caused by the necessity of replacing or repairing any such item.

Manufacturers warranties are standard with some of our products. For example:
All Innovate Motorsports wideband products are covered by a 1-year limited manufacturer's warranty covering parts and labor for repairs of any manufacturer defect. They are good people to work with and will take good care of you and we will help ensure you are taken care of.

AMP EFI, MS3Pro, MS3Pro Plug & Play and MSPNP2 EMS Systems are covered by a 1-year limited manufacturer's warranty covering parts and labor for repairs of any manufacturer defect for the original purchaser. Furthermore, original purchasers of AMP EFI models MS3Pro ULTIMATE & EVO may upgrade, by way of online product registration, to a Limited Lifetime Warranty within 30 days of purchase. Please visit for details & product registration.

Other manufactured products (fuel pumps, etc) have warranty information included in the product listing.

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