Holley ECU Harness

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This particular engine harness has been in the making for over a year!  CASPER’S has been adapting and developing engine control harnesses for just about every aftermarket ECU for many, many years!  As quality, repeatability, and producibility are always our focus, we wanted to make sure this harness is 100% complete and tested before we release it to the public.  While we have many prototypes in the field for testing, the outline below is what ultimately has become our production harnesses.  


  • Built on the same assembly lines, using the same equipment and personnel as our OEM products.  

  • ALL terminals are put on by press - depending on size between 3 ton and 30 ton presses are used with appropriate tooling

  • All wire is cut by machine to specified lengths

  • All seals are applied by machine.

  • All connectors are original, new OEM brand name. 

  • All wire is rated at 125*C per automotive standard and is automotive spec TXL, GXL, and SXL crosslinked wire. 

  • Splices inside harnesses are made using Ultrasonic Wire Bonding technique, required by OEM’s for production harnesses.

  • Sealed 40A and 70A relays are included.

  • High temperature race spec harness wrap included. 

  • Prior to shipping, the harness is 100% electronically inspected, point to point for continuity as well as resistance, and serial numbered to ensure it will work as soon as you drop it in!  

  • A/C is included without using up an input or output from the Holley.

  • Powermaster is included - If you don’t use a powermaster, harnesses are available to utilize these connectors as high-power feeds for items like alky, accessories, etc.  


  • This harness is expandable!   We provide an accessory connector underhood which has your 4 input, 3 output, +5V feed, sensor ground, chassis ground, constant +12V, and dedicated relay driven 30A switched +12V feed. You can add just about ANYTHING to this harness without having to modify wiring in any way.  

  • This harness is adaptable! With pre-populated hybrid connectors, you can easily plug-n-play your ignition system from the stock Buick CCCI, to smart coils, and everything in between.  Provisions are included for custom plug and play cam or crank sensors as well.

  • This harness is upgradable! By default, this harness will run the factory fuel pump through the factory wiring.  With a simple plug-n-play upgrade, you can run 8 gauge wire - power AND ground - to your fuel pump, capable of 70 Amps!   Even the biggest pumps can easily be controlled. 

  • Battery positive  and negative cables (stock location) are included!  This also includes junction boxes to add any additional positive or ground wiring.  

  • We open the door to new injector options!  With a plug and play harness, you can use Multec, EV1, EV6, EV14, Denso, or just about any other injector connection imaginable!  

  • CAN distribution inside passenger compartment AND underhood.  This will give you the ability to add a Holley Dash, or EGT logger, or ANY number of CAN controlled devices, like gauges, controllers and more  to the Holley network.  

  • While this harness will be available direct, many “Value Added Vendors” will be able to provide additional components and programming along side this harness.  Watch for information shortly!