Need help merging together wirings of 1990 5.7/350 in cabin with 1998 5.7 vortec eng

**Aksl** · 08-29-2018

Hello Dave, thank you for feedback.
As you have noticed, i have repined the L31 vortec engine (underhood) wiring for 0411 PCM, that can control and the vortec injectors and the 4l60e.

You are absolutly right it is challanging, i am braking my brain for this setup, still thinking should i keep the underhood fusebox, i know folks choose to cut it out, to make the wiring more simple and neat. The L31 underhood with 0411, can work by it self, controling everything and the 4L60E, with out the incabin wiring, like most make a bench for L31.
But want to merge everything to work together. I wonder why there is still no rewiring schem or file out in the net yet for this setup, like Lextech has made for the 0411 repining file, it's realy a mistery..

**dave w** · 08-30-2018

Planning is a good thing when re-wiring.

The option to delete the '0411 fuse block is a solid plan.

The list of old TBI wiring that can be reused:
Fuel Pump Relay wiring.
Battery +
Battery -
Ignition On / Start
Old TBI fuel injector wiring
Old TBI coil power
ALDL Wiring (reconfigured)
Add HO2S wiring
Add MAF Wiring

dave w

**Aksl** · 08-30-2018

Originally Posted by dave w

Planning is a good thing when re-wiring.

The option to delete the '0411 fuse block is a solid plan.

The list of old TBI wiring that can be reused:
Fuel Pump Relay wiring.
Battery +
Battery -
Ignition On / Start
Old TBI fuel injector wiring
Old TBI coil power
ALDL Wiring (reconfigured)
Add HO2S wiring
Add MAF Wiring

dave w

Thank you Dave.

**Aksl** · 10-16-2018

Ok as i called the thread i have done some homework)), i have made some connector wiring pinout charts for two main connectors i have to merge: The C100 Bulkhead connector & C200 passenger side firewall connector (in 1990 k1500 its called C273 connector, in 1996-1999 C200).

I have obtained a new used untouched wiring of a 1998 Tahoe with fuse-box and everything uncut/untouched, and started looking on how to merge my in cabin wiring with new under-hood, i as well have my old under-hood wiring. And what confuses me is this, the old under-hood wiring was looped with the in cabin wiring, because everything was going from engine to cluster and modules behind cluster & behind the dash and then to the ECM with corrected by modules or cluster signals i guess, not direct. Where as in 1998 vortec the under-hood wiring is hooked up directly to the PCM. So for me to hook up my cluster and all the modules inside the cabin as well as under-hood modules that my old wiring goes to like ABS & Cruise control, how should i pair the wirings Sensors -> new PCM - > Incabin, and if one wire has to go to both, just split it? Or does it have to be sensors -> cluster and in cabin staff -> New PCM.
For example my VSS signal used to go from trans case to C100 Bulkhead -> Cluster -> C273 passenger side -> ECM. I can live that as it is and get the VSS signal to my New PCM from C273 connector, but that will bee a hell of a loop of wires around the cabin, or i can just have the VSS signal go directly to the PCM From the trans case, and then have separately signals go from pcm to speedo etc..

As well i`m a bit confused on how to merge these connectors C100 & C200/C273 together correctly, totally different wires in old vs new C100 & C200/C273 connectors, only a few are coming and going to from to same place in one-another...

Hope my tables will help someone and ease their job.

If someone could suggest me a way out with my headache, i would appreciate, a psychologist will do but only if he has experience in swapping L31 into 1990 L05 truck.

**dave w** · 10-17-2018

There are several ways to accomplish your wiring goals. A good first step would be to Identify and label the necessary wires. Be careful about wire colors, for example the fuel pump relay wire is usually green with a white stripe just like the AC wire is usually green with a white stripe. Skills reading schematics and skills using an OHM meter is a requirement, not optional.

dave w

**Aksl** · 10-18-2018

Hello Dave, thank you for warning me about colors, i assumed there isn't different color for every connection, all thaw they could have achieved it using shades and stripes like they do. Yes i am marking every wire, to see exactly what it is and where it's leading to, as well to see what i can throw away, like EGR for example, i have it closed with a plate, so no need wiring connection for it.
But still quite confused, on the best way to merge my engine compartment wiring old and new together via C100 & C200/C273 between each other, for best configuration achievement...