Need help with LS wiring

[lts70]

Trying to help my boy get his LS swap up and going. Hoping you guys may be able to point us in the right direction on some wiring. We bought the engine and re-pinned wiring harness already done. It was easy to find where all of the plugs tied into the motor but there are some wires without plugs that we are trying to figure out. Whoever reworked the wiring harness did a good job and even labeled these wires with numbers. Problem is there is no key that tells us what each number means. Must have been lost in the shuffle as the motor and wiring harness moved from owner to owner until it found its home with us. Each wire or bundle of wires is labeled 1 to 25 with a few that are just labeled with a name. Hoping someone may be able to give us some good advice. The 5.3l motor came out of 2007 1500 Silverado Classic. It is a drive by wire. I will attach a list that shows the number associated with each wire or wire bundle. I will put the numbers labeling the wires in parentheses ().

(1) - two red wires out of relays (power into harness)

(1) - two red/white stripe

(1) - two orange ( pins 20 & 57 on blue plug) PCM Power Supply

(3) - white out of relay (trigger wire from ignition or power to fuel pump?)

(4) - yellow out of relay (trigger wire from ignition or power to fuel pump?)

(5) - green (pin 42 blue plug) Low speed fan control & blue (pin 33 green plug) Engine cooling fan control

(6) - orange/black stripe & blue

(16) - green/white stripe (pin 50 green plug) vehicle speed output 4k

(18) - gray, gray/black stripe, dark blue, light blue bundle (cruise control wires) Three to the column switch and the light blue to the brake switch

(22) - green (Pin 58) communication wire

(23) - purple (Pin 33 blue plug) TCC Brake Switch

(24) - brown/white stripe (Pin 34 blue plug) malfunction indicator light MIL cont

(25) - white single (Pin 10 on green plug) Tach output signal

(Park switch) - white (Pin 34 blue plug) PRND A Input

(Starter) - large purple

(Battery cable plug)- multiple (Generator Battery Charging Module) voltage sensor on neg cable, from what I can tell part number 15857953 or 19432142, cant find one available to buy anywhere


Any help identifying what to do with any of these wires would be greatly appreciated.

[ls1nova71]

With the harness already modified and the plugs cut off, its going to be tough to figure out what someone else has done. You will likely need to get a voltmeter and start checking to see where the wires go. Shouldn't be that hard to do as there aren't that many wires that are needed to make it run. But some wires, like the green with white stripe can be for different things, such as the fuel pump relay signal and the speedometer output both use that color. I would go to LT1swap.com, pull up the pin outs and start checking wires.

[lts70]

Updated info in red for what I could figure out with the voltmeter as far as pin out.

In blue is what I think the function is as far as I can tell from online information.

If you have any insight on the remaining wires or see something that seems off help is always welcomed

[ls1nova71]

18 is going to be cruise control wires. Three of them go to the switch and the light blue one goes to the brake switch.

[Pitpig]

Didn’t use the purple starter wire from the LS harness. Used the purple wire from the ignition switch, through the neutral safety switch to the starter

[lts70]

Thanks! Getting closer to having things nailed down. I highlighted the items in green that I still haven’t identified.

[lts70]

Would this be a good fuse and relay set up or should we be looking at something different. I would like to error on the side of having plenty of expansion room for AC and any other systems we may want to add.


http://www.currentperformance.com/sh...erelay-module/

[lts70]

We had a little more time today to play with the voltmeter. Got the rest of the wires figured out.

Figured out that the the pair labeled (1) two red/white stripe wires are power to the generator battery control module.

Figured out the first relay puts power to the injectors, coils, transmission pin E, and 02 sensors. Seems like a lot for one relay to handle but that’s how they did it. Is it common to run all this off of one relay?

The second relay is for the fuel pump.

The pair labeled (6) Orange/black stripe and blue also goes to the generator battery control module.

Still cannot find a battery control module for sale anywhere so I’m not quite sure what to do with all of that system.

Also confused at whether to run everything off the two relays or try to split the systems out and put them on their own circuits.

Seems like it’s taking me forever to figure this stuff out wish I had more time to dive into it.

[bigmoe]

When I had my harness modified the guy finished mine off with 3 relays and 4 fuses (maf, Fuel inj, O2 and pcm). Not sure what each relay does. See the picture.