ClusterTruck; because that’s what it is

[clay68c10]

Now time to start the wiring. I'm wanting to keep this easy to service, so the harness and fuse box needs to be a unit. I want it easy to remove when pulling the engine, like stock. Lay it over the top of the intake and go.

My previous EFI swaps have been TBI. Those were easy to disconnect on the engine side. The LS setup is not.

For me, that means that any circuits not run thru the fuse/relay box need to have a connector so they can be unplugged.

The fuse/relay box has the switched ignition relays and fuses (pink wires) for the PCM, injectors, coils, and sensors. It has the fuel pump relay/fuse and the AC clutch relay/fuse. And last, the constant power (orange wires) for the PCM.

I'm using the factory C100 connector. That one has the cruise switches, serial data to OBD connector, Check Engine light, RPM, and a couple others that may be useful.

That leaves me to make some connectors:

1-pin
To the fuel pump

2-pin
Hi/Lo fan relay triggers

3-pin at the 68 harness
Temp sender
Starter solenoid
Coil power, now used to turn on the pink wire circuits

4-pin for PCM signals, to go to the interior
Brake switch to TAC
Brake switch to PCM
Clutch switch
Shift light. **It's in the manual trans diagrams, maybe it'll work, maybe not. I've used it in TBI so it's worth a shot**

[clay68c10]

Originally Posted by SCOTI

I've been doing similar work on a g-body w/the battery tray repurposing theme. Funny how parts change over the years but somehow can still work well if things are thought through.

Will you be running the a/c compressor in the OE LS location?

It is fun to use these newer parts. Part of it is the challenge to make vs buy. It's nice when it actually works.

Yes, I'm definitely going to run the compressor down low. That's one upside to the Hooker frame stands. Plus the cost is so reasonable I don't mind buying vs fabricating.

[clay68c10]

Here's some mock up pics of the wiring layout. I tried a couple of different locations but this seemed to make the most sense.
***Don't forget to stick a hood hinge in there*** I almost put my fuse box in a bad spot.

[clay68c10]

Here's my solution to mounting the PCM:
Trim bracket, and add fasteners.

[clay68c10]

Now, the TAC module.
I figured it was easier to lengthen the TAC to pedal harness than anything else, so the module gets mounted to the core support. I added some threaded inserts to it for simplicity.

[clay68c10]

I used the split woven loom to cover it, It's a pretty slick item, I like that you can just open it back up if you need to add anything later. I tape the ends just to keep it from fraying.
I kept the big grommet on the pedal end. I'll just enlarge an existing firewall hole near the pedal for the pass-thru.

[clay68c10]

On to the exciting part of wiring the fuse/relay box. I try to do most of this work before I have to run anything connected to the LS harness. Power (ckt30), relay grounds or powers (85/86), and live side (87) of relay powered fuses. This is much easier to do sitting down inside with good lighting, heat, and frosty Wyoming beverages.

[clay68c10]

So, 5 relays and 6 fuses. I just did it this way because it fits into this box well and serves my purposes.
Relays and fuses 1-3 are the pink wires
Relay and fuse 4 is fuel pump
Relay and fuse 5 is AC compressor
Fuse 6 is the orange constant power circuit

Relay 6 is an extra and I pinned it for 30 and 87 but no 85/86. I may or may not end up using it someday.

Yes, those are Benz relays. Leftovers from my dealership days...

[clay68c10]

A shot with the buss bar. These are in TBI trucks, on the passenger firewall. A good grab at the junkyard.
I'm also running a one stud central ground. It's a nice way to make sure all these added circuits have an adequate ground.
The power and ground are both using the stock battery cables. Nice to have those, so may as well use them. The power lug will get some shrink tube or a different end, that's a lot of exposed metal there.
I'll make 3 mounting legs for the fuse/relay box. Now it's just held on one corner, at the convenient little flat spot on the wheel well.

[clay68c10]

Here's the 2-pin for the fan relays, I'll mount the relays to the core support by the TAC module. Also need a fuse box for the fans. This one takes the square fuses. It'll work for headlight fuses and anything else I may add later.

[SCOTI]

Damn. This def isn't your first LS swap rodeo.

[clay68c10]

That’s funny Scotti, it actually is my first LS swap. I’m just trying to think of everything with an eye toward how the factory did it and serviceability. I’ve overlooked the service aspect before and didn’t want to do that this time. Basically, pulling the engine shouldn’t require cutting any wires or removing any big items.
I do a fair amount of install wiring on emergency vehicles at work, so that helps with being able to plan and lay things out.

[SCOTI]

Originally Posted by clay68c10

That’s funny Scotti, it actually is my first LS swap. I’m just trying to think of everything with an eye toward how the factory did it and serviceability. I’ve overlooked the service aspect before and didn’t want to do that this time.
I do a fair amount of install wiring on emergency vehicles at work, so that helps with being able to plan and lay things out.

All the more impressive then. The electrical work (re-work) does look like OE quality.

[clay68c10]

Thanks man, that’s my goal.
Fingers crossed that it all works as designed.

[BigBird05]

Clay68c10, here is a tip on extending wires. Stager your splices, don't put them next to each other. If there are a lot of them you end up with a bulge inside your loom.

[clay68c10]

Haha yeah, I thought of that after I made the big cut on the TAC harness with my cable cutter.
I did stagger them on the area where I put all the pinks together to come into the fuse box.

[russellmarling]

Clay, where did you source that fuse block with the J-case fuses? That would be perfect for my project. I'm loving the OE quality wiring you're doing- so many people overlook this on their builds.

[clay68c10]

russellmarling; I’m not sure about the source of the 10 fuse box. It was in the surplus pile at work. I’d like to know so I can get a blank lid for it. The current one has designations on it for the fuses that I don’t need. Thanks for the compliment, I appreciate it. Just trying to do clean work.

[clay68c10]

I've done some more incremental work over the past month, there's light at the end of the wiring tunnel.
I extended the C100 harness to go into the cab and built a 6-pin for the other circuits to run with it.
For now it's going thru the 71 e-brake square hole. I'll be running the 68 style, so I'll decide where to do the firewall pass thru later.

[clay68c10]

I'm moving down the list now, finally.
It's time to get the hydroboost and clutch master figured out.
The Capt Fab setup is really handy and well thought out, definitely a good purchase VS trying to fab something myself.

[clay68c10]

I'm using the hydro out of a 79ish G30 van. It has the flare style fittings, which just required me to swap out the pressure fitting on my LS pump. Thanks GM for using the same basic pump for so many years.
The van pressure hose to the booster fits sorta-ok. Maybe a square body hose set would fit better. I'll worry about that later, I can also do some tube shaping if needed.
The 79 push rod for the booster is way too short, the 71 manual brake rod is about an inch too long. I did a quick chop and shape, and that was good to go.
You can just see it in this pic. I intentionally cut it a little short, since I mocked it up with the adjustment bottomed out. It should be in the range after everything is assembled "for real" at a later time. Right now, it's turned out a just a bit and there's a little pedal freeplay.

[clay68c10]

Here's some shots of the Capt Fab linkage. It's very adjustable. I set it up so the master push rod is close to horizontal. It seems to cycle well. It bottoms out the master just shy of the floor. I'll probably build a pedal stop on the R side, where the clutch rod used to attach.

[clay68c10]

It's been a long time since I've updated here. The usual reasons; family, life, other house and Jeep projects.
I have gotten some things done, and am working my way back into getting more done.

I had a chance to get some newer Tahoe buckets and I think I'll try to use them. The newer GM seats mount weirdly, but I think I can make it work.

[clay68c10]

I also got my fans mounted and finished up the relay wiring. Ground one pin for low speed and both for high. That was a happy day.

[SCOTI]

I've seen those seats pop up on a couple of builds now (Squarebodys). I also was curious on the mounting arrangement.

My buddy is a GM Tech that does alot of Interior/Trim related work so I hear about many nuances of the newer stuff (ex: windshield has to come out to pull the dash to access the heater core on a 5/6 GEN f-body ). We were talking about those seats & wondering how well they might adapt to earlier iron.

How is the seating position as the sit in the pic/s vs an OE seat?