Ls Wiring Harness

V8killR4U

Active Member
Joined
Jan 21, 2003
What are you guys using for a wiring harness and why? I have a stock truck wiring harness and need to know if its worth the hassle to modify it to work with the GN or simply get a custom harness to work with my setup.

Any info is appreciated. Thanks
 
I bought a Holley HP system and it came with the ls harness. What are you using for a ecu
 
I bought a Holley HP system and it came with the ls harness. What are you using for a ecu

I planned on using the stock ECU possibly and going with a FAST later down the line. I would prefer to do it right the 1st time around though and just be done with it but that all depends on cost...
 
We used the stock ECU/harness with HP Tuners. Dug through the harness removing all the crap I don't need to clean it up to fit the car and setup better (we remove MAF and do a SD setup, delete the secondary O2's and so on). If I remember it left me 5 or 6 wires to connect to the car, the rest plug straight into the PCM and each sensor. Def more painful then Holley setup for sure, that setup is a easy plug-n-play. There is a big price difference though. If you got the money to spend get the Holley. I know of 2 people using it and love it.
 
I used a Howell. Nice piece, not cheap. [AIRC, $700+.]
If I do another, I'll call PSI, or rework the stocker, if I have it. [I have access to all the correct wiring and connector parts]
http://psiconversion.com/
Ask for Jon. I've talked w/ him several times. Always willing to help. And, they have a good rep on LS1tech.
As for the stock harness, I'd do that, since you may switch to a FAST at some time...
The nice part about doing the stocker is, you can custom make all the lengths to fit exactly as you want. Not something you will get in an aftermkt piece...

Just like FOX News....We report, you decide!:D
 
I got a bit less than $1700 in the Holley HP system.
That includes:
Ecm
main power harness
Main ls1 24x harness
Holley coils
Holley coils wiring harness
Injector harness
5 bar map sensor
ntk wide band sensor
iat sensor

The harness plugs into all the rest of the factory sensors.

My friend has it on his Buick ta engine. It is the coolest thing since sliced bread. It took 3 passes before the ve table was at zero correction! The data logging is second to none...especially if you get the dominator. I've played with accel, fast and feast xfi, have seen motec, HP tuners, aem, etc.. The software on the Holley is the best laid out IMO. If you got a xfi, you could sell it and get the complete Holley system for what you sell it for.
They were having issues with the stock ls1 coils but that's supposed to be fixed. That's why I went with their coils. It would be even less if you used the stock coils.

I was quoted $2200 for a xfi. I believe that was minus a harness. The fast needs a separate xim box to control the coil packs.
 
We used the stock ECU/harness with HP Tuners. Dug through the harness removing all the crap I don't need to clean it up to fit the car and setup better (we remove MAF and do a SD setup, delete the secondary O2's and so on). If I remember it left me 5 or 6 wires to connect to the car, the rest plug straight into the PCM and each sensor. Def more painful then Holley setup for sure, that setup is a easy plug-n-play. There is a big price difference though. If you got the money to spend get the Holley. I know of 2 people using it and love it.

BMF / Kev

Why did you guys choose the Holley set up over the FAST or BS3? I dont know anything about the Holley that's why i'm asking so be great to hear from people who have it and why that over XFI or BS3
 
I got a bit less than $1700 in the Holley HP system.
That includes:
Ecm
main power harness
Main ls1 24x harness
Holley coils
Holley coils wiring harness
Injector harness
5 bar map sensor
ntk wide band sensor
iat sensor

The harness plugs into all the rest of the factory sensors.

My friend has it on his Buick ta engine. It is the coolest thing since sliced bread. It took 3 passes before the ve table was at zero correction! The data logging is second to none...especially if you get the dominator. I've played with accel, fast and feast xfi, have seen motec, HP tuners, aem, etc.. The software on the Holley is the best laid out IMO. If you got a xfi, you could sell it and get the complete Holley system for what you sell it for.
They were having issues with the stock ls1 coils but that's supposed to be fixed. That's why I went with their coils. It would be even less if you used the stock coils.

I was quoted $2200 for a xfi. I believe that was minus a harness. The fast needs a separate xim box to control the coil packs.

Kevin,

Great info man, I know other folks are asking the same question and wondering which way to go, the Holley set up sounds likes it make $cents over the XFI and BS3... I'm sure finding someone to tune it comes into play too.
 
I think anyone that has the will to learn can use the Holley system. Just keep the tune conservative while learning and you'll be fine. When I get mine fired up I will share the tune with anyone that wants it.
 
yeah I've got it already. I've been using it to try to datalog my other LS1 car. I understand how to load a tune in, but I don't know how to adjust the fuel tables at all.

You don't happen to have a tune for a stock LS1 on 8 psi (procharger) with 42# injectors, do ya? ;)
 
just qurious i'm doing a turbo ls swap myself and i too plan on using the holley hp system, what are you guys doing for the rest of the electrical in the car,like the starting system ignition switch, headlights, power windows ect ..................any help would be greatly appreciated thankyou....
 
just qurious i'm doing a turbo ls swap myself and i too plan on using the holley hp system, what are you guys doing for the rest of the electrical in the car,like the starting system ignition switch, headlights, power windows ect ..................any help would be greatly appreciated thankyou....

I'm doing an 86 T.. I am leaving the body wiring alone, except for the dash. [Will be an Autometer array that I make myself.]
The engine and body harnesses are separate plugs at the firewall. I left the body side untouched, and unplugged, & opened the engine harness, to get at the input power wires, [3 red on fuseable links], the purple start wire, and the coil power wire. This allows the stock column, fuse panel, etc, to retain power, ground, and starter w/ the stock key. I used a donor harness for this, [85 El Camino], as the orig harness is uncut, and all stock, including the hard looms. [FOR SALE, BTW!]:D
I have a stabilized voltage supply, and I've tested this several times. So far, so good.

An ACCURATE wiring schematic is a good thing to have.;)
 
yeah I've got it already. I've been using it to try to datalog my other LS1 car. I understand how to load a tune in, but I don't know how to adjust the fuel tables at all.

You don't happen to have a tune for a stock LS1 on 8 psi (procharger) with 42# injectors, do ya? ;)

No tune specifically for that combo. Have you been on the EFILIVE forum? Someone there may help. They don't usually just send tunes, but rather will help you write 1..[Improves the learning curve slope!]:D
Are you using a custom op system, [COS]?
Is the car up and driving?
Have you done any data logging?
What PCM are you using?
Who did you buy the system from? Did they provide a base tune?

Send me the tune file, and I'll see what I can find. Add in any data logs you may have, too. codymspt@bellsouth.net
 
I'm doing an 86 T.. I am leaving the body wiring alone, except for the dash. [Will be an Autometer array that I make myself.]
The engine and body harnesses are separate plugs at the firewall. I left the body side untouched, and unplugged, & opened the engine harness, to get at the input power wires, [3 red on fuseable links], the purple start wire, and the coil power wire. This allows the stock column, fuse panel, etc, to retain power, ground, and starter w/ the stock key. I used a donor harness for this, [85 El Camino], as the orig harness is uncut, and all stock, including the hard looms. [FOR SALE, BTW!]:D
I have a stabilized voltage supply, and I've tested this several times. So far, so good.

An ACCURATE wiring schematic is a good thing to have.;)
yes i have the stock body harness still in tack but i sold the engine harness and computer...so im just trying to figure out how to get power to the ignition switch lights ect
 
yes i have the stock body harness still in tack but i sold the engine harness and computer...so im just trying to figure out how to get power to the ignition switch lights ect
i guess im trying to figure out where to add 12volts ....on engine side plug at the firewall...thanks
 
No tune specifically for that combo. Have you been on the EFILIVE forum? Someone there may help. They don't usually just send tunes, but rather will help you write 1..[Improves the learning curve slope!]:D
Are you using a custom op system, [COS]? Don't think so
Is the car up and driving? Yes
Have you done any data logging? Not recently
What PCM are you using? Stock 1999 PCM it came with
Who did you buy the system from? Did they provide a base tune? a member here, but the car is from another guy. It came tuned but doesn't run well.

Send me the tune file, and I'll see what I can find. Add in any data logs you may have, too. codymspt@bellsouth.net

It'll be a few days, but I'll get it out once the snow clears off and I'll datalog it some, then I'll email it your way.

Thanks.
 
Top