sprayed99

iTrader: (15)

This isn't my first harness to mess with, but it is my first harness with a limited amount of ignition fuses.

Below is the wires i have in the harness to connect to ignition power.

8-Injector wires
2-Coil wires
2-O2 sensor wires
1-Transmission wire (from case connector)
2-PCM wires

So given you only have 3 ignition power slots....all 30amp fused. How would you pair them up?

Please do not respond if you havent done work on an engine wiring harness.

Thanks Guys!

rotor vs. piston

iTrader: (3)

Injector/coils
o2 sensor (assuming you're talking about the heater circuit)
Tranny/PCM

bczee

iTrader: (12)

To do it correctly, I would want to isolate the circuits to more than just 3 fused circuits... Why is it that you have only 3 IGN Hot Circuits? Can you not add some more? IMHO... I would recommend you add the extra circuits.

But I guess technically, you could run them all from one Fused Circuits.. Not saying it would be a good idea... But I guess you could make sure that each of the three circuits add up to, but do not exceed the 30am fused rates.
Most likely, if all goes ok and you don't run into a problem, you'd be ok.. but if you did, it would be harder to isolate the problem circuit and possibility of frying something that is hanging off of the same fused circuit.

Good luck.. I myself would not like to make this suggestion..

BC

sprayed99

iTrader: (15)

I appreciate your concern, but several harness makers run the 4 fused gang box (1constant and 3 ign) without issue.... In fact every speartech harness I have installed is done this way. With all due respect I will follow those that do this for a living.

And to answer your question on expansion. Its a 32 ford with barely enough room for the american auto wire highway 22 wiring system that I have in it. That is also why I only have 3 slots


Keep the replies coming guys.

the_merv

iTrader: (88)

Here's the FACTORY LS1 Setup.

IGN Bank1 and Bank2 is actually two wires, powering both Coils and Fuses on that Bank. Each a 15A Fuse.

MAF/O2's/TRANS/EGR is powered by one 12v with-key-on (Ignition) source, 20A Fuse.

Then you have a PCM Constant Power 12v, and a PCM Ignition 12v, these are two different circuits.

I would install a 4th.

sprayed99

iTrader: (15)

I understand the pcm having the constant 12v and the ign 12v. The constant has its own port on the fuse block. I guess I need to just cram a 4 gang box above the hwy22 and separate the 2 banks... gonna be a tight bitch but oh well.

Thanks for the advice

the_merv

iTrader: (88)

No prob..what I listed there are the 5 that power an LS1. I tell people all the time it is that simple.

sprayed99

iTrader: (15)

I know what whats on the harness. Just thought maybe Icould get away with 3 ign fuses. I would solve a space issue for sure... sucks having a chopped and channeled 32 truck with AC, Power windows and the rest of the wiring.... that and im OCD about the way things lay out.

BP Automotive

iTrader: (3)

It can be done with just three fuses, but that makes for a pain when troubleshooting. You would also have to upgrade the wire that would supply the coils and injectors.

Most who only use three circuits will put all of the coils and injectors on one circuit.

With that being said, that is not how I do it. I use 4 ign power fuses

With the LT1 GM had the Transmission, O2, TCC Supply, MAF all on the same circuit. When the LS1 came out GM put the Transmission on its own circuit(in the engine harness).

On the trucks GM ties the Transmission into the PCM OFF/RUN/CRANK Voltage.

I wire the Transmission solenoids into the engine sensor circuit as I like to have the PCM on its own dedicated Circuit.

1989GTA

"I like to have the PCM on its own dedicated Circuit."

That is the way I did mine and for the same reason.