Features
- Manufactured100% from scratch, in-house, in the USA.
- Modular system is extremely flexible and adaptable for different configurations of coils, throttle body and intake manifold.
- Completely covered in high-quality woven nylon loom with heat shrink breakouts.
- Every connector lead labeled with permanent white-on-black heat shrink labels for a guess-free installation and professional look.
Harness Length
This harness is offered in two main trunk lengths. The long lead length is approximately 6in longer than a standard Holley harness, and is plenty of length for comfortably mounting the ecu under the passenger seat of most vehicles. The short length is intended for mounting the ecu on the dash bar of a caged car or in the glove box, without wadding up a bunch of excess length.
Starter
This harness features a starter solenoid lead built-in, fully loomed and labeled. This lead is terminated with a #10 eyelet standard. This lead can be terminated with a spade terminal as for some aftermarket starters, or the molded connector used on OEM-style LS3 starters upon request.
Oil Pressure
The oil pressure lead lands at the factory port, behind the intake manifold by default. Extending the lead to drop down by the block-off plate above the oil filter is available upon request.Â
I/O Stub & Power Tap
This harness system features I/O stub and power tap connections terminated with the same Metripack connectors as a standard Holley harness, but with a lead off the main trunk of the harness that's actually workable.
Depending on selections for oil pump and VVT, auxiliary outputs will be required to be used.
CAN Bus
This harness features two male CAN bus connectors, the same style as Holley standard.. One connector includes power and ground, the other is CAN data only. These are compatible for use with any Holley CAN-based device or accessory.
Front Accessory Stub
One nice feature included in this harness is a built-in accessory stub, terminated with a Deutsch style connector near the front of the engine. This prevents the installer from having to run additional wires with the engine harness, saving installation time and making a cleaner result. This connector stub features -
- Ignition power through a 470-ohm resistor, to use for alternator exciter.
- Accessory power that can be used for either an electric water pump or a/c compressor. This circuit feeds through the harness back to the power distribution stub.
- Ground terminal feeding through harness to back of cylinder head.
Sensor Tap
This harness features a terminated stub for splitting key sensor signals, if needed for piggybacking with factory controls or other external controllers.Â
- Crank position
- Cam position
- TPS - Cable drive (If running DBW throttle, the DBW throttle harness features signal split as well)
Ordering Information - Please Read!
ECU
This harness is compatible with HP, Dominator, Terminator X and Terminator X Max ecu's. Your ecu selection is for our information only.
Wideband O2 Sensor Connector Type
If running a Terminator X or X Max ecu, you're prompted with an additional question for o2 sensor connector type. If the vehicle is built for racing, and upgrading to an HP or Dominator ecu is a foreseeable possibility, select the HP / Dominator option. This specs your harness to be terminated with the standard Holley 8-pin wideband o2 sensor connector. A wideband adapter (comparable to Holley part no. 558-463) is included, but when switching to an HP or Dominator ecu, the adapter can be discarded, and the proper sensor for these ecu's can be connected directly to the harness.
If the vehicle is more of a street-driven / daily driver, and it is not ever anticipated to run this harness with an HP or Dominator ecu, you can opt to have the harness terminated directly with the 6-pin connector for the Bosch LSU4.9 sensor. This eliminates the need for the adapter, which can make for a cleaner installation, with one less potential failure point in the system. Should plans change, the harness can still be modified for use with the appropriate o2 sensor for HP and Dominator ecu's, but will require cutting and re-crimping.
Injector Style
This harness features an injector harness stub, compatible with injector harnesses from Holley. Harness kit includes our Holley EFI-compatible injector harness specific for the LS, based on your choice. If you already have an injector harness from Holley, it can be used with this engine harness, but our injector harness routes much nicer.
Ignition Coil Style
The ignition leads are broken out with extra length, allowing flexibility to cleanly install the coils either on the valve covers or remote-mount. Your selection automatically adds the proper coil sub-harness kit to your cart, to make connections directly to all eight coils.
Throttle Body
This harness is highly adaptable and compatible with both cable drive and electronic drive-by-wire throttle bodies, without leaving unused connectors dangling in plain sight in the engine bay.
For cable drive throttle bodies, we provide an adapter harness to extend out to the throttle body and idle control valve. If running drive-by-wire, the cable drive stub tucks out of sight and out of the way under the intake manifold.
MAP Sensor
This harness is offered with the MAP sensor lead terminated for the specific type of MAP sensor that you're running, depending on your induction or intake manifold setup.
The SSI transducer style is known best as the 1/8npt cylinder style sensor available from Holley, LowDoller Motorsports or RIFE.
Many aftermarket intake manifolds, including the BTR equalizer, Trinity and Holley hi ram feature a mounting boss for the Bosch 1BAR and 2.5BAR sensor, commonly found on factory LS3 and LSA applications.
Additionally, we offer the option to terminate the harness with a Bosch TMAP sensor connector, which is both manifold air temp and MAP merged in one sensor. These sensors fit the same boss as a LS3 / LSA-style Bosch MAP sensor, and are common with aftermarket supercharger setups.
Knock Sensors
The harness can be terminated for gen 3 style knock sensors (in the valley cover), gen 4 style (on the sides of the block) or none. High compression, heavy nitrous, and high-boost applications intended primarily for drag race with Holley efi typically choose to forego knock sensors, due to either susceptibility to false knock, or the slowness for the sensors to react in a useful way, or both.
Fuse / Relay Center
The inline fuse and relay on an off-the-shelf Holley engine harness always seem to get wadded up way up into the dash, leaving them inaccessible for troubleshooting and diagnosis unless you stand on your head in the passenger's seat and cut 173 zip ties. For this reason, we designed the harness with an external power lead, where injector power, coil power, ecu power, starter solenoid power, fuel pump output and more are terminated with a Deutsch connector for easy hookup in a centralized location to your choice of relay center, or even a PDM like the RacePak SmartWire, HardWire PDM or ecuMaster PMU.
For a true standalone installation, we offer a basic yet inclusive relay block that includes:
- 40A relay for injector power, plug-and-play
- 40A relay for ignition coil power, plug-and-play
- 40A relay for aux / fan
- 40A relay for fuel pump
- 35A relay for A/C compressor or electric water pump, plug-and-play (See Front Accessory Stub above)
- Starter relay, plug-and-play
- Isolated clean ecu power relay, plug-and-play
- 10ft unterminated flying lead wires for fuel pump, fan and switch activators.
Power distribution stub lead is same length as I/O stub, for easily using outputs to activate additional relays.
ECU Main Power Harness
Holley ecu's require an external power harness that must be connected directly to battery positive and negative terminals. We provide a high-quality alternative to the standard Holley harness in various lengths, eliminating waste and putting the main power fuse in the proper spot on the harness. For reference, Holley's main power harness (p/n 558-308) is approximately 13ft long.