Pocket

iTrader: (24)

Why wouldn't it?

InfernalVortex

iTrader: (4)

Im VERY confused here, but it's harder since i dont have any harnesses to look at.

My car was a 305 TBI, 700r4 car. But now it's got a carbed 350 and a T56 in it. To do the T56 I just got lazy on the wiring and jsut put the two big giant purple wires together. Always said I would do the rest of it later, but never did or felt like I really needed to.

So you keep saying to get a harness that matches the original transmission to the vehicle. Should I get a dash harness to match a T5? Or a T56? Or should I get a 4l60e donor harness since that matches the dash harness? Would I be better off getting a T5 dash harness?

I REALLY, REALLY hate wiring, so I avoid it like the plague. But Im thinking since I dont have any AC or cruise control and as ingle fan and so on that it SHOULD be pretty easy.... But Im not really sure what harness I need to start with.

Ugh...

scooter

iTrader: (11)

There never was a T56 3rd gen, i'd have to be the T5, but you can get by without. I extended the wires from the PND connector at the console over to the clutch pedal to hook up to a NSS when I did the T56 conversion back in 1999 or something

CatmanFS

I need to figure out 95 or so lt1 with a 4l60. i guess a early model lt1 ecm and setup would work. The upgrade to the pcm in 94-?? is pointless because the 4l60 aka 700r4 doesnt use it.

Pocket

iTrader: (24)

The dash harness dictates what you use because its the hardest to replace

So for your auto to T56 swap, you'd use an auto engine harness and still follow the standard auto to manual wiring changes for the dash. All of it comes from the old auto shifter connector
Top two are 12ga, these go to the clutch switch at the pedal. Splicing them together works, but the safety switch is bypassed
Middle two are back-up lights. Connect these to the back-up switch on the trans
Bottom two are P/Neutral. Ignore these

Thats it

LT1 PCMs come in 3 flavors
92-93 SD, similar to TPI SD
94-95 OBDI <-- most common for swaps
96-97 OBDII

Only the earliest can control the lock-up function of a 700R4/4L60. The latter two can control a fully electronic 4L60E, but not an older trans

If your 95 engine came with the trans, its a 4L60E, not a 4L60, so youd need a 94-95 PCM. 96-97 PCMs require additional parts that didnt come on the older engines such as a crank pos sensor mounted in the timing cover. 96-97 engines can still use the 94-95 PCM, even with the newer harness, but the reverse wont work

CatmanFS

This is part of the reason why I'm "downgrading" my lt1 so I can use the 92-93 setup with the 700. I know there are differences, like the timing cover, the maf and emissions setup, but are there any true differences in the block and heads as far as the 92-93 and 94-95 lt1s?

Pocket

iTrader: (24)

If you're going to dumb it down to keep the archaic trans, Id cut a hole in the intake for a distributor and run your TPI electronics

No, the block and heads are no better/worse for any year LT1. 92-93's had a slightly different intake/rail and the TB had a stud for a TV cable

CatmanFS

So you really suggest cutting a distributor hole in my intake? Aren't there any advantages to running the 92-93 ecm over the tpi ecm?

Pocket

iTrader: (24)

Not really. Its a sealed ECM where your TPI isnt. I cant see rebuilding a harness just for that

skirocz28

Pocket, are you getting caught up? I still need the C100 harness.

CatmanFS

I was just going to do the rewire myself. I don't have the money to have a harness professionally rewired. I barely have enough to get the parts I need in the first place. Just exploring different possibilities.

///DAN///

iTrader: (1)

Hi I'm putting a lt1 starter in my 84 z28 w/ carbed 355 vortec motor so I do not need to change any wiring except for the starter . I've read that you only need the batt and purple wire , what happens to the other starter wire? Thanks for your help.

WTR388

Which other wire? Big wire from battery to starter, purple wire from the C-100 to the starter and there are 2 more red wires from the C-100 that go to the same lug as the big + wire on the starter, they are your hots for your chassis side (lights etc).

Billy Decker

Can anyone help me. Is there anyone i could pay to make me a Carburated wiring harness for my 1988 camaro. The car used to have a 350 TBI and i did an engine swap to a 355 with 4bbl carb. I would like a harness that eliminated the ecu and keeps my accessories running like stock like ac and gauges. PM me if anyone interested. Thank You

1986chevycamaro

I'm trying to figure this out. if you use the sts fuse box you are making a stand alone harness for the engine right? so the main fuse box of the car will control inside and outside light radio and that's it right?

WTR388

I made a standalone harness.
From my C-100 (the larger half) I have the starter solenoid wire, my ign hot wire and two wires that are the (+) wires the power everything in the chassis, like your lights, ctsy stuff etc.
I had pocket make me a nice little relay/fuse block that I put in a fairly out of sight spot on the frame rail next to the battery.

I ran my chassis (+) wires to their own dedicated in line mega fuses off the battery to get rid of the fuse-links.

On your STS fuse block you'll have the main power in and then it distributes out from there, I only needed 3 relays (ign, fuel pump and fan).

I enjoyed the wiring honestly, and will possibly end up doing a harness for a friend's 91 BMW to LS swap if he gets the parts together.

1986chevycamaro

so the connector c207 plugs into the third Gen computer right? so if I don't habe one can I just got to a salvage yard and pick one up?

Lurbie

iTrader: (3)

C207 connects the passenger side of the engine harness with the IP harness. The ECM connectors have some wiring connected in there as well, but C207 does not connect to the ECM directly.

Yes, you could go to a salvage yard and cut this connector out if you're missing yours from a previous modification.

1986chevycamaro

I don't have a computer I do have the harness. I wanted to know if I can just. pick up any computer? sorry for the miss understanding

CharcoalBird

iTrader: (4)

Why isn't this a sticky?

Pocket

iTrader: (24)

Billy, PM me. I can put the AC in it too like your other thread asked

Some cars need to add a fuseblock for the conversion such as 82-87 carb cars. 85-92 EFI cars have sufficient fuses in the stock block under the dash

The Caddy fuseblock is a compact option for those that need the fuseblock

You're mostly correct, but there are a few direct connections from the ECM/PCM that hit the C207 such as the ECU fuse, speedo, MIL, P/Neutral

Depends what you're doing. Carb conversions dont require a computer at all. TPIs can use an box with the right number, but the PROM/MEMCAL have to be correct for the engine. LT1s are pretty flexible, LSx also meet a certain range but also several V6 boxes can be used with a reflash

Its linked in the LS1 swap sticky

Juan_Garza

iTrader: (1)

So the other connectors are just cancelled on the ecm I only keep the c207 connector right?

Pocket

iTrader: (24)

With a carb conversion or alternate EFI swap, then yes, all the old ECM connectors are removed. The C207 is needed for all EFI conversions and most carb conversions

Crashbandit63

Hey does anyone have contact info for Pocket?I'm interested in getting a harness made.
I sent a pm no answer yet

drunck1

Im more of a visual person when it comes to DIY's sometimes as the wiring gets me confused. Anyone have a picture of the C207 and VSS buffer box bypass you talked about? Just need to get my gauges working, I found the buffer box but got confused on how I am suppose to wire this. LT1 PCM > C100? bridge connectors on VSS buffer box only? Thank you for any help you can provide. its the last thing I need as i need to bleed air out of the LT1 but without the gauge working I am not sure what temp its running at.

R13_Braz

Send him an email. That's usually the best way to get in touch if he's out and about. You can email him directly from this site.

Crashbandit63

Cool thx

Pocket

iTrader: (24)

Email works best when Im out of town. If I havent been active for 2 days, its a good bet Im traveling

drunck1

Hey Pocket I sent you an email as well if you can get back to me whenever possible that would be great.

JCS94

iTrader: (1)

Hey Pocket, if I am keeping my lights and all of those related plugs, I can just leave those on the C100 and just call that part good right? Finished my LS harness and starting on my third gen harness and going to use this guide to clean it up and just wondered about all of the lighting wires and all that. Thanks in advance dude!

andersonracing

thanks for the great info, but I have a few questions. im doing a lq4 swap in my 87 T/A and I want to use the stock fan and fuel pump relays, how do I wire these up , what wires do I keep out of the factory T/A engine harness? I also am going to use a t56 and the motor harness had a auto trans, how to wire up from the speed sensor to the ECM. thanks guys for the help, Im trying to get this car done before LS Fest 2016.

grngryoutmyway

iTrader: (1)

All but reverse lights I believe.




Fan and Fuel diagrams are in this thread.

https://www.thirdgen.org/forums/ltx-...formation.html

Cable driven speedo you need a converter box. I'm sure this is covered somewhere, but I can't find the thread.

I'm just reposting Pockets info from other threads btw

68-87Chevy

Hey guys,

I had a guy wire me the harness. I guess it's just a standalone harness. He's listed all the connectors I need to get the engine going. Stuck on what to do with the C207. I can't find an exact match of wiring pinouts theres a couple of colours wrong, but I'm mainly not sure of what I'm supposed to connect these wires to. All the wires the harness builder lists for me to connect are elsewhere, mainly off the C100. Ecm fuses, fuel pump fan relays are all on a fuse block he wired into the harness, and aside from speedo input (not much help to me anyways being an 1987 V6 cable driven)/I don't see anything I need to connect... Or am I wrong? Any help is Appreciated

QwkTrip

iTrader: (22)

For the most part, people use C207 as a place to pick up switched B+ power, and feed in the speed signal for speedometer. If you already took care of those things then you are done.

QwkTrip

iTrader: (22)

You can also use C207 to operate the "Service Engine Soon" light as a substitute for the MIL lamp that would have been in a 4th gen. Connect pin R46 of the LS1 PCM to the correct wire at C207 and the PCM will run the SES light. In my case (1989 Firebird) that is C207 pin C.

If you are unsure which is the correct wire then use a multi-meter to do a continuity check from the ground side of the SES light bulb in the gauge pod to the connections at C207. The one that has continuity is your winner.

68-87Chevy

Thanks. I found out my fuel pump wire runs through there as well, so the Mil, Fuel Pump and keyed power for my OBD II port should be it. MY speedo is not needed at the moment so Ill leave that out. Thanks for the continuity idea for finding wires, never thought pf that.

Another point, would I be correct to say the PNK/BLK wire out of c100 is a keyed power too?

rsrmoore

Subscribe

scooter

iTrader: (11)

Why?

Why? WHY WHY WHY?

WHY?

WHY do people do this? Just subscribe to the thread, don't show yourself to be an ID10T

Lurbie

iTrader: (3)

OK, I admit I didn't know this either. Thanks for sharing.

mwfrels

After years as a member of e-mail list server type sharing it took me a while to get the hang of forums. Old habits can take some time to die off...

M

Chris Luinstra

I have a question about this.. What if you swapped in an LS but kept the 700r4 and the PCM was reprogrammed to accept 8k PPM? How could you retain the usage of your original speedometer? My trans am was a '87 TPI electric speedo.

Bossman519

anyone still do these harnesses? Its gona take me 8 years to do it myself.

KnightPhoenix

I felt the same way going into my swap. Rainbow Spaghetti can be terrifying, but It's really not as bad as it seems. Just download all the wiring diagrams for your car, and the LT1. . . Print them Out. Go through wires one by one removing what you don't need, and separating/labeling what needs to be married between the two harnesses.

Once you start removing the unnecessary wires it starts looking much less scary. I tackled mine in like 30 min bites, focusing on just a couple wires each time. . . Kept me from getting overwhelmed and frustrated.

If you're trying do the swap on a budget then it's worth it to do yourself.

Stephen Ray

I am a new member to group and have a few questions. I have a 91 z28 original TPI car i am putting an LS in to.The guy i sold the motor to wanted the engine harness also . So i unplugged the C100 connector from firewall and from computer . Now of course i have no power on anything . What pins are needed on the connector on firewall to power lights and interior? I separated the headlight harness from the engine harness so it is still plugged in.Thanks

Stephen Ray

Ok how bout it you have already removed engine harness and left headlight harness plugged in. How do i get power on everything ?

Billgluckman

This photobucket thing is killing me. Anyone know another place that has this info or is someone working to straighten this out. I'm about to start an ls swap and all the help I can get.

IROCDOWNUNDER

The C100 plug has the main power from the battery going through it into the car , you have given it away with the motor , you should be able to pick it up with a wire diagram as I did . its pretty straight forward

indebt

iTrader: (1)

I've searched and read but still a little confused. On my 86 Camaro C100, do my 2 red wires and purple go to the starter, or just purple. Red wires to a distribution block maybe, but is that needed? Also read where pink wire isn't used on some swaps, so am I using it? Lastly my C221 has fuses for Inj1 and Inj2, so that's what I tie into my pinks from injectors correct. My battery is in the back. Thanks.

JCS94

iTrader: (1)

only your purple goes to the small post on your starter out of the C100 wires. Both reds go to the distribution block, they are inputs to your car from the battery. If those are not hooked to a distribution block, dash and everything else does not get power. Pink is a B+ OUTPUT as an ignition 12V source. So anything in a swap that says "ignition voltage" or "keyed hot" will be tied into that. In my swap I used the large pink wire as my main ignition hot for my main relay to power my O2S, coils, injectors, and MAF/trans if app.) for your battery from the back, you should have one thick wire going to a distribution block and have your C100 wires tie into that, and you can run another wire from the battery to your large post on the starter, or jumper off of the distribution block and have a short thick wire run from the dist. Block to your starter. You can use C221 pink wires as some ign. Hot wires. Remember if you use the thick pink wire, it is NOT fused so anything that is fed from my thick pink wire from the C100 I have fused at a home-made fuse block as a safety precaution.

indebt

iTrader: (1)

Thanks man, I appreciate it. I haven't drove my car in about 3 years almost and I'm over it. Trying to get this thing done and enjoy it!!!