Re: Restoring Rusty
 

LOL, thanks I had Ray Charles weld that for me with his feet, thank you I appreciate that but you are not running the Manual Lever Position Sensor (MLPS) block box which gets in the way, that's the whole dilemma, it just doesn't work with that important box, even Lokar Tech Support say they only had it setup with it removed

Re: Restoring Rusty
 

True, I'm not using the trans. switch. The Lokar has the NSS, and the only purpose I could think of for the trans switch would be for reverse lighting. Our LS PCM's don't really need the switch

Re: Restoring Rusty
 

A Z-bend right where the weldment is placed would do the job. They look purdy too.

Re: Restoring Rusty
 

Wiring Part Deux (... Progress) - a lot of folks find wiretization intimidating that's why I would like to share the steps I am going through to re route the harness in my beloved '74 GMC, rather than just sharing before and after pics

Findings: in this driver side inner fender PCM layout your reach will be dictated by the following sensor wires:

Alternator
Throttle Position Sensor
Idle Air Control Do Hickey

basically all the sensors on the nose of the engine, but the good news is that we will have enough reach!

MAF just shown for completion, a coin toss will determine actual placement, ha ha

I do plan on shortening and repining the longer wires to clean up the last foot of the harness aka the birds nest

Re: Restoring Rusty
 

Grounds Demystified

having liberated all of my ground wires from my 2001 GMC Sierra 4.8L 4L60E engine wiring harness, I learned that only the following four components use what I call external/dedicated wire grounds:

1. Coils

2. Oxygen Sensors (some don't use a separate ground wire, but ground by housing contacting the down pipe)

3. MAF

4. MLPS (Transmission Neutral Switch / Range Sensor)

In addition the PCM itself consumes four grounds:

1. Blue Connector PIN # 1

2. Blue Connector PIN # 40

3. Red Connector PIN # 1

4. Red Connector PIN # 40

To roll our own Fuse/Relay block we borrow one of the extra grounds from something that got deleted, and we do the same for the little OBDII port, it too needs a dedicated ground

The following sensors get their grounds from the PCM I call these internal grounds:

1. Blue Connector Crank Shaft Position Sensor PIN #21

2. Blue Connector PRND Trans PIN #32

3. Blue Connector Transmission #41

4. Blue Connector Throttle Position Sensor PIN #54

5. Blue Connector Camshaft Position Sensor PIN #61

6. Blue Connector Coolant Temp Sensor PIN #63

7. Red Connector IAT Sensor PIN #57

Re: Restoring Rusty
 

just wanted to share some progress pics of my engine wiring harness re routing, really like how it is turning out although it does not happen over night, but a little each night, best part is that no lengthening of wires required to reach the PCM on the driver side inner fender = Win!

Although I unpinned all the wires and re routed them I opted for the lay it over method rather than cutting and recrimping new terminals on the extra long ones, I just didn't feel I had the skills to match the factory crimps, mea culpa! I still might could cut and solder the really long wires, we'll see.

The following PINs / Wires were left in on the BLUE CONNECTOR to roll your own fuse/realy block, gauges, etc.

19 Pink - Key on power

20 Orange - Allways hot power

33 Purple - TCC Brake Switch

57 Orange - Allways hot power

58 Dark Green - OBDII port

57 Orange - Allways hot power

75 Pink - Key on power

The following PINs / Wires were left in on the RED CONNECTOR to roll your own fuse/realy block, gauges, etc.

9 Dark Green/White - Fuel Pump Relay

10 White - Tach

46 Check Engine Light

50 Dark Green/White - Speedo

Re: Restoring Rusty
 

Wired up my LS starter (it's an iddy bitty thang) last night and got the engine to turn over by turning the key in the ignition switch. I like taking baby steps and not taking on everything at once, so I will share what I did to make this happen, I know this is super easy, but here it goes if for nothing else to hear myself say it, but it may help someone out:

(battery stays in the OEM location on the passenger side)

1) Main thick black battery cable goes from the negative battery terminal to the front of the passenger side cylinder head. (hole in OEM battery cable terminal had to be enlarged slightly to accommodate the metric head bolt)

[just for completion in addition a skinny black wire runs from the battery negative terminal to the radiator core support, to ground the chassis - that's unchanged]

2) Main thick red battery cable goes from the positive battery terminal to the thick stud on the new LS starter.

[that's nice, but nothing happens at this point, yet]

3) In keeping with tradition, we run a medium thick red wire (yes that is a technical gauge description in my book, ha ha) from that same thick stud on the starter in #2 above to the bulk head black little square box on your firewall by the brake booster. This supplies main power to the cockpit.

[at this point if we was to turn the key, our gauge cluster should light up, but that's about it... oh and our annoying always on fan will start to blow... Joy!]

4) at this point power goes from the battery to the starter (logically that is not necessarily how the electrons flow, but don't tell my Biology teacher, hee hee) and then daisy chains from the starter to the bulk head, and more specifically to the ignition switch on the steering column (no not where you insert the key... but below) ok but still no clicky click on the starter, unitl ... [wait for it] ... until we run the purple wire from the bulk head black little box on the firewall by the brake booster back to the starter's skinny winnie stud. This purple wire is the "signal" wire it tell the solenoid (aka electronic switch) on the starter when to turn ON the starter.

... and that's it folk's aside from the battery cables, it's just a two wire hookup, the red and the purple wires. I know I made this silly but I hope it helps out the OverThinkers(TM)

I blew up my bulk head / fuse block to show you that the red and purple wires are just pass through and do not feed the fuse block directly, I actually like to divorce them from that box and run em through a different hole in the firewall and not the bulkhead.

Re: Restoring Rusty
 

If you're re-pinning a lot of connections you'll want a decent set of crimp tools...

The most versatile pair of crimp tools in my terminal box are the five cavity two operation Delphi 12085270 & 12085271. They are priced around $100 each but they will properly crimp most of the automotive and powersport connector terminals I've run into... From Packard 56/59 and Weatherpak or Metripak 150/280/480/630 to Molex GT150 and Mate-n-locks on ATVs and Mowers.
The single crimp operation tools are connector specific and just as much money as these tools that crimp the insulation and the conductor in separate operations.
12085270 with three insulation seal crimp cavities and two conductor cavities.
Attachment 1923356
12085271 with three conductor cavities and two insulation wing cavities.
Attachment 1923357

The odd stuff like the old Delphi double width Packard 56 & 59 two-wire and Pak Con two-wire terminals and there's another tool for the Packard 56/59 & Metripak 630 10-12ga terminals but I'd only buy em if you need em. Mine are infrequently used but I needed them for a couple jobs. The customers got to pay extra for the odd tooling I needed and now I have em.

For the Deutsch DTP, DT, & DTM and Amphenol CPC machined pin connectors I use the Daniels Military Aircraft tools AF8 & AFM8. You can get open wing terminals for the Deutsch DT & DTM, Canon, and AMP CPC families that will crimp in the Delphi tools but the eight indent Mil crimp on machined barrel terminals produces a fast zero defect field repair and I don't have to worry about the quality of the terminals. I use the snot out of these tools. I bought them used. Daniels will re-calibrate and repair them for a pretty reasonable fee should I ever need that service.

Re: Restoring Rusty
 

For a high current connection like the 12ga Red Circuit 2 wire I'd bite the bullet and extract the old terminal so I could crimp on a new Delphi terminal to insert in the bulkhead plug. It's a PITA to pull the male Packard terminals out of a connector but this connection is a wee bit more than slightly critical. Butt splices tend to heat up and get loose over time. Brass Delphi terminals, crimped with the proper tool, do not.

GM didn't put a lot of circuits in the 1973/74 bulkhead plug. The 79 & later trucks had a lot more realestate in that plug along with ATC/ATO fuses rather than glass cartriges... It does take a little body work to fit the larger bulkhead plug tho.

Re: Restoring Rusty
 

You are reading my mind again...

Re: Restoring Rusty
 

Weatherpak Connectors are not rated for the current a 12ga wire can carry. Even tho Delphi provides terminals sized for 12ga wire the connector itself can only safely carry 15-20A max.
https://www.whiteproducts.com/faqs.shtml

Metripak 150 are rated at 14A
Metripak 280 are rated at 30A
Metripak 480 are rated at 42A
Metripak 630 are rated at 46A
Metripak 800 are rated at 60A
https://www.whiteproducts.com/metripack-faqs.shtml

If you're going to the trouble of crimping on a new terminal just crimp on a Male Packard 56 or 59 and eliminate the extra connection... IIRC the 12ga power wire is a 59 terminal but don't quote me on it.
The bulkhead studs are a great place to connect with common ring terminals and a fusible link.

Re: Restoring Rusty
 

ha ha, you are using the page I was going to use against me, so how much current does the purple starter wire carry I thought it was only like 10A? (I doubt GM would send any more juice through the ignition switch under the dash, risking a fire) and a proper Weather Pack connector with 20A rated innards should be more than plenty for it, am I wrong? again not saying what is the max a 12 gauge wire is rated for I am talking about our specific application in our trucks, where I think the 12 gauge purple wire is already overkill

Re: Restoring Rusty
 

Less than that on the purple wire. Probably more like 1 Amp. It's energizing an electromagnet coil in the starter solenoid... basically a big ole high current relay.

If you're using the PCM controlled starter wiring from the LS donor it's probably of the order of 5-10 ma to the starter enable on the PCM and 150 ma to the relay in the fuse-relay centre. It may really only be slightly more than that for the Delco MT starter solenoid S terminal but I tend to pad stuff out the nearest amp for safety.
The only reason to use 18ga wire for the starter solenoid S terminal is vibration resistance. You could likely send the energize current over 24ga wire and not worry about it if you didn't have to worry about vibration and such.

Re: Restoring Rusty
 

Quick question for you.

Is there any problem with running these milliamp loads through the old square body switches? For example, using the stock ignition switch to trigger only relays instead of actual loads?

Reason I ask, it seems that a very small electrical load might not "spark" the gap on a crude switch. But then, if a multimeter can sense the switch, I guess a relay or the pcm should sense it as well.

Re: Restoring Rusty
 

The old starter wiring is on the hot side.
The Delco MT starter solenoid is a contactor... essentially a big hairy relay to switch a couple hundred amps from the 4ga battery cable through the series wound starter motor.
As long as the PCM is expecting Hot and not Ground it should work just fine. You can use a relay with the coil hot lead off the ignition switch CRANK wire to switch a ground and essentially reverse the output polarity if needed.

Re: Restoring Rusty
 

I wouldn't the LS donor engine comes with complete stand alone wiring harness that easily runs on it's own simple fuse box you can make like this:

http://www.lt1swap.com/fuseblock_obd2port.html

just take all the pink wires and two orange wires and off you go, I will be posting my fuse block hybrid design on here shortly

Re: Restoring Rusty
 

Is your wife on vacation or something? I happen to know that you don't have oak flooring in your garage... Thank you for the explanations and demystification of the LS wiring process. I'm enjoying following along. I will refer back to this one it's my turn. In about 14 years, give or take.

Re: Restoring Rusty
 

Is this something you would need to get from one of the "neighborhood, outdoor, drive-up retailers"? Or is it available if you get the right prescription?


Good work hatzie, again thanks for putting the information out here for us to use. I'm a big fan of having the right tool to do the job well.

Re: Restoring Rusty
 

They're 1/4 and 1/2 turn-to-lock HDPE plastic body round connectors similar to some Cannon plugs but not made of metal. I believe CPC is and acronym for Circular Plastic Connectors. The J1939 diagnostic connectors on Transit coaches and over the road coaches are Amphenol CPC.
https://www.te.com/commerce/Document...ish&s_cid=1046

I work on electronic systems on Public Transit vehicles... both rubber and iron tire. I've encountered both the Amphenol and Canon plugs at work. Can't say I love either one but I can deal with them.
The right tooling makes things so much easier. Keeping the actual tool count down when I fly with them is a must. There's still a 3 bag and 70lb per bag limit at check in for Diamond Four Million Milers.

Re: Restoring Rusty
 

Great write up, although after reading through, I'm now terrified of wiring again!

Re: Restoring Rusty
 

Looking at a whole vehicle harness is overwhelming. The key is to break it down in bite size sections that you can wrap your head around.
For example... The forward lighting harness is just a few wires... A modern LS engine contains a handful of sub functions. Break em up as individual separate systems so it makes sense to you... Sensors, Fuel, Ignition, Charging, etc. The functions may interleave inside the PCM but the wiring is separate.

Re: Restoring Rusty
 

So started looming my engine wiring harness. The point of this thread is to show you that if you take your time wiring doesn't have to be that bad, you don't have to do it all in one shot.

I decided to do it on the truck cause I was too lazy to take it off yet again and I convinced myself this way I can ensure every sensor has the proper slack or lack there of.

I will upload more pics as I do more branches. Found that a little Stevie Ray Vaughan on the good ol' hi fidelity stereo pairs really well with a 12 oz refreshment of your choice and makes the split loom slide on a bit easier, ha ha.

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So I pretty much bought every size of black high heat automotive split loom from 1/8" to 1 1/2" I could find in The Amazon

Re: Restoring Rusty
 

using the high heat Tesa brand tape that Brandon of LT1Swap.com recommended, again from Amazonia

Re: Restoring Rusty
 

yeah that's pretty much all I did tonight (still recovering from my surgery so hold your judgement, ha ha, and don't tell my doctor) so just the passenger side four injectors, coil, and not fully in view the MAF sensor wire [good enough for the girls we go with]

hey do any of you know if they make a throttle bracket minus the cruise control hole on it, I aint got cruise control and would prefer a cleaner look, and don't feel like taking the death wheel to it just yet

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if any of you kind souls could let me know how to remove these pesky GM gray wire harness connectors off the metal bracket that would be great, I am missing one and I tried to remove some at the junkyard and almost went postal, for the life of me I could not get them off without carnage

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those silly white bar codes on the fuel rail will keep me up at night, must peel them off

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yup, inch by inch, she will get done

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... and on to the other side, twice as many sensors/components on this side

Re: Restoring Rusty
 

had to use a bit bigger loom on this side as there are twice as many wires, including the TPS, IAC, Alternator, Temp, Knock Sensor, etc. plus the Injectors and the Coils

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and here is how it all turned out

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I did build my own fuse block following LT1Swap.com and a hybrid of the stock, and I think it turned out great

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also to keep things simple, I mounted the PCM on the driver side inner fender, I thought about running the harness through the firewall and mounting the PCM on the inside of the cab, but I was surprised to find a lack of space for it there, and this way all engine stuff is in the engine compartment, so there's that

Re: Restoring Rusty
 

You don't have salt and much in the way of water to contend with in Sacramento.
I'd still spray the open relay and Pak Con fuse terminals with WURTH HHS-K or WURTH HHS-2000 creeping lube or something similar.
The thing I like about WURTH HHS is it doesn't seem to attract dirt like spray greases and it keeps the water and other corrosive stuff away from open electrical contacts like fuse panels in the engine bay.
You can probably get it from your Mercedes, BMW, Porsche, or Audi dealers for an exorbitant extravagant price or just buy a can from an online vendor.

Nice clean wiring job.

Re: Restoring Rusty
 

Nice clean job, sir. Barring any unforeseen programming glitches, you're gonna love the swap. A word to the wise, though. Hang on tight to the steering wheel when you say to yourself "Lets see what this baby will do"

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thank you, ha ha, and message received!

Re: Restoring Rusty
 

Looking good. Your clean and simple explanation of the wiring is pretty fantastic. I just might have copied and pasted all of that into a folder for future reference.

https://drive.google.com/uc?id=1VA65...lOPDVkxPrT0Gp_

Re: Restoring Rusty
 

hillarium 👊🏼

Re: Restoring Rusty
 

Thank you very much, did you get a chance to see my series called: HP Tuners Tutorials it is guaranteed to cure your insomnia.

Re: Restoring Rusty
 

Looks really good Greg..!!