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Discussion Starter · #1 ·
Hi everyone.

I am actually building a roadster but I think this forum is the best place to seek help for my question. You see, I am putting (have put) a LS3 into my car. Going well so far, all installed, exhausts on, looks good.

I am also a fair way down the path of installing the GMPP ECU and engine harness as well. I have the loom run, the connectors all mostly connected, so is OK so far.

But now I am putting the Ron Francis loom into the car. I do believe this loom is very similar between 33 and Mk4.

And where I start to get confused is where these looms start to overlap. I mean they both have fuel pump outlets. The kit comes with a starter motoer solenoid, but LSx engines have their own solenoid. How do I connect to the alternator? The LS3 loom already connects to the alternator, so is that enough?

So does anyone have any info or guidance on high to integrate the LS series engines? Does F5R publish anything for you 33 guys?

Please help as I am a little stuck just now.

Many thanks
 

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when i put my ls1 in my roadster 10 years ago ,i sent the engine harness to speartech to have the unnecessary stuff removed and it came back with all the necessary connections labeled and a fuel pump rely, i believe he sells harnesses ready to go now. if you search the web you can find out how to get in touch with him,he use to be a gm fuel injection engineer and is quite familiar with their systems. if your good at reading schematics you could figure it out yourself but it is time consuming. someday i will have time and money to finish mine , good luck with yours.
 

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I'm useing a Ford harness fron a 06 Mustang .Same thing what you are doing.I wired the Ford harness in and remove the fuel pump and alt from the R.F. harness.I connect the RF wires to the Mustang fuse box where the battery cable connect to.
 

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Discussion Starter · #4 · (Edited)
Hi guys,

so I have been studying the wiring diagrams and I think I need to do the following:

1. The LS3 has its own connections for alternator, so I only need run a cable from the alternator across to the battery positive or to the LS3 starter solenoid. And I guess I can delete the Ron Francis alternator cables completely.

2. And given that the LS3 starter has its own solenoid, I shall delete the F5 solenoid and run the starter cables to the LS3 solenoid. Actually I wonder if I could just go to the back of the alternator with the red power cables and just extend the blue start signal to the solenoid? For me this is a shorter route.

3. I am unclear on the COIL/EFI wire and the EFI CRANK wire. I guess the COIL/EFI would provide power to the ECU when the key is on, not sure on the crank wire.

4. Relocate the fuel pump wires to ECU harness.

What say you all. Sound right?

Thanks
 
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