lt1b4c

I had a question about what wiring I would need to do if I have a complete 97 LT1 with harness and computer going into a 1988 z28? Is it just a ignition wire hookup to the computer?


Thanks J.R.

Pocket

iTrader: (24)

Bare minimum swaps still require repinning the body connectors on the LT1 harness. The end result looks ugly and often brings tons of problems if you make a mistake (hard to troubleshoot)

This is what i recommend. It involves removing everything and running each wire individually so any issues with year pinout changes, component addition/deletion/relocation, repairs etc will be handled in one step
https://www.thirdgen.org/forums/ltx-...rt-finish.html

lt1b4c

Sorry for my ignorance but I guess I just dont understand the need to redue the harness, the LT1 harness wires already plug into were they go on the engine.

Could someone help explain this to me, the car doesnt have any gauges or anything and im just looking at getting the car running. The car was in a fire and the factory harness was burnt by were the break booster is so the guy before me just converted it to carb.

Thanks, J.R.

Pocket

iTrader: (24)

The harness plugs into the engine, but in stock form it wont plug into your 3rd gen. Fuse wires, gauge wires, power wires, ground wires etc have nowhere to go

lt1b4c

So I would have to match the wires coming from the computer to the fuse block and power wires to match the wires going into the computer? I dont care for the guages at this point since I have all new autometer guages to go in.

I dont think I have the wires going to the fuse block and stuff.

lt1b4c

what if the harness i got also came with the fuse block and wires?

Ill post pics of the harness I have maybe someone can tell me something

lt1b4c

So this is how you do it, take all the wires out of the old harness, and wires out of the new lt1 harness and move all the new lt1 wires to the old coupler that plugs into the fire wall by following were the old wire schmatic for the new lt1 wires?

Pocket

iTrader: (24)

Not exactly

You strip both the 3rd gen and LT1 harnesses, then rebuild the LT1 harness to best fit your option load out. Last you splice the 3rd gen body connectors (C100 is pictured, C207 near the old ECM) onto the new harness so it's plug and play

lt1b4c

so you follow the schmatic for the third gen pinouts on the c100 as pictured to know where to place the lt1 harness wires in the third gen body connector so it is plug and play, then second you do the same for the c207 for the computer as well? by doing this it will still use all the factory third gen wires that are on the other side of the firewall of the c100 that goes to the fuse block?

Pocket

iTrader: (24)

Pretty much

The C100/207 contain your fuse/gauge wires so the biggest job is identifying and grouping them from the LT1 side

lt1b4c

So you depin the wires from both harness's and you take the wires from the lt1 harness which is picture 2 and repin them to the old third gen harness which is picture 1 and then plug them into picture posted above which has them going to the fuse box and your all set?

Pocket

iTrader: (24)

No, read the threads about it. The only thing you depin are the PCM connectors and thats only to speed resizing the wires and deleting non-critical circuits. The LT1 body connectors get cut off, the 3rd gen body connectors are left alone and the proper wire leads are spliced into the swap harness built from the old LT1

lt1b4c

here are some pictures of the progress

lt1b4c

Engine bay is complete and ready for the swap.

Pocket, do you have any info on the c207, what is it and where do I find it? What does it contain? Do both lt1 and original tpi harness have them?. I have everything figured out except for the c207. Whats the process at this point?

Pocket

iTrader: (24)

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

Its a 3rd gen body connection near the old ECM. It contains a few gauge functions and several fuse wires

lt1b4c

I recently found out that I have the Impala SS harness for my LT1 swap. I was told since it has its own fuse box integrated into the wiring harness, the only wires i need to worry about are matching up the gauge wires and ignition wires in the c100. Also the fuel pump relay wire that goes to the c207. Is this correct?

lt1b4c

Anyone'? no-one has ever used an impala harness???

chevyowner02

iTrader: (3)

I used one from a caprice same thing but I used the thirdgen fuse block no need to have to box's.

Pocket

iTrader: (24)

Its not that big of a deal

Find the body pinout and assign them to the 3rd gen wiring accordingly. I will warn you, B-body LT1 harnesses look terrible

lt1b4c

Yes I agree haha, right now im just trying to get it running so I can enjoy it this summer. I added some more pics of some connectors I cant figure where they go.

Thanks, John

lt1b4c

One more

rdog30

http://www.lt1swap.com/pictures/1995_caprice_C205.jpg
http://www.lt1swap.com/pictures/1995_caprice_C204.jpg

the top link is the little white 10 pin connector. The bottom link is the 37 pin black connector on the impala harness.

rdog30

some of the connectors your holding need to go the maf sensor, IAT sensor, and others that I'm forgetting. maf sensor has one yellow wire in it.

rdog30

1st pic one of those goes to the alt. the other 2 are not used. went to the ac i think.

lt1b4c

Thanks rdog30 I will go and try and match some of them up

rdog30

37 wire connector





cavity connector/color


B1 Dk Blu Theft deterrent Module A3 "fuel enable
signal"


B4 Dk Grn/Wh Vehicle speed signal from PCM, makes your elec. speedo work



B6 Tan Goes to DLC (Data Link Connector) 9
C1 Pink Goes to splice, then IGN switch, fuses-
11,12,13,14,15
C2 Gray Goes thru grommet to fuel pump
G1 Orn Goes to splice, then, IGN "Run", Circuit
breaker 2, fuses-16,17,18,20
H1 Wh This tach signal (Impala only)
H5 Orn/Blk Goes to splice, Orn/Blk wire of Trunk
release relay, and Brake/Trans interlock
solenoid. It is "floating Grd, allows these
to operate IF in Park or Neutral
H6 Wh/Blk Grounds the following to an under hood
grd:Theft deterrent module B5, Cruise
Module E, Park/Neutral switch A,
J6 Ppl Goes to DLC 2

G1 and C2 are the ones you need to get it started.
G1 needs to be a switched ign. source.(power with the key on) from your cars original harness
C2 should run down to your c207

lt1b4c

awesome rdog30, this is what i needed to know. thank you so much

lt1b4c

when using the impala wiring harness for the lt1 swap, i'm trying to sort out the wires i will need from the original tpi harness. Does anyone know which wires i will need to save from the original harness? I know A4 and F4 go to power distribution and I have located the wiper and starter motor wires.. Just wondering if I need anything else?

lt1b4c

I need a little help on mounting the 6 speed master cylinder at. The car was originally a auto. I need help trying to figure out where to mount it and how.. the threads on here now don't really say in regards to the location of drilling holes on the firewall. There are no holes from the factory either.

supr_fly03

iTrader: (2)

Are you using third gen pedals or 4th gen pedals?

I cut the firewall out of a V6 5spd third gen and used it as a template.

You could use the 4th gen clutch master cylinder support to locate and drill the holes in the firewall. Just make sure you bolt the pedals up good and connect the front support to the cowl area.

lt1b4c

that must be how you guys do it, see i'm using the 3rd gen pedals.. whats the best way to go about doing this now. I don't think i have access to a firewall like you did.

supr_fly03

iTrader: (2)

-Your clutch pedals should have two bars hanging down for the clutch support. Loosen the bolt that those bars go to (the pivot bolt for the pedals).

-Bolt the third gen pedals up to the firewall.

-Swing the clutch support bars towards the firewall. Make sure the carpet and insulation is out of the way!

-Use the "U" bolt from the clutch master cylinder to align the bars on the firewall and mark the holes to be drilled.

-Drill the holes out. Make sure the U-bolt fits through the holes.

-Find a piece of cardboard or thick construction paper and make a firewall template using the clutch master cylinder.

-Place the template on the firewall and match up the mounting holes and then mark the large oblong hole for the clutch master cylinder and push rod to go through.

-I used a hole saw that was the diameter I needed and made two holes. Then I connected the holes together with my air-saw (sawzall will work too) and made sure everything fit.

-Use a file to clean up the cuts and remove the burrs. Slap some touchup paint or rattle can it to keep rust away.

-Get some foam weatherstripping to seal the master cylinder to the firewall and botl it up and go!

lt1b4c

I have some more wiring questions. I hope you guys can help me figure some of this out. I have figured out that I have a OBD1 harness from a caprice or impala. I am in the process of de-pinning some of the wires and have questions.

The first picture I have wires that i need to delete. It looks like the body connection that the wires pass through. My question is, is there anyway to remove this block so I can remove the wires I don't need?

Second picture- What are these connection?

Third- This picture has 6 or so thick red wires that go straight to the fuse box, does anyone know what this connector is?

89rs454

Looking good man your on your way to new found power lol. I did this last summer and it took me 2 months to really get it done engine tranny and all wiring just me and my dad, and my cousins 4th gen 97 lt1 all stock just like mine except 3 inch catback is scared to race me lol it just pull harder seat of our pants and he don't want to race.

I will help you as much as i can man I did all the wiring myself don't think you have to spend 400 to get the job done with someone else doing your harness, do it you self and it will make you twice as proud when your cooking them backs. lol if you need any help let me know.

lt1b4c

Thanks man! So you said yours is bone stock? Have you ever ran it at the track? I'm curious as to see what she will do!

Right now I'm at the point where I just de-pinned all of the wires out of the computer connectors and I'm just tracing the wires to the connectors that I know I'll need. Basically all the connectors i took pictures of.... I cut out. Now I'm fighting the battle of all the common splices everywhere. What year LT1 engine was your swap out of? OBD1 or OBD2?

lt1b4c

Working on the ignition circuit. I have all the wires traced following the wire diagram but out of the coil I have a pink wire, according to the diagram the wire goes to a 10 AMP fuse then to ignition run. The wires I have the pink wires go into a splice and I have two pink wires coming out of the same splice that are PCM pins that the diagram does not show where they go. Does anyone know where these two pins go? picture shown.

89rs454

95 Formula OBD1.

89rs454

Run your pink ignition wires to any switched 12v fused source, should do the trick.

lt1b4c

I ran them to PCM B30, and D3. I'm guessing that is where they go? and then coming out of the splice I have them going to a 10 AMP fuse then to ignition run.I got most of the harness mocked up today!

89rs454

Looking good! Your talking the pink wires coming off the pcm? hmm let me look into that to verify and i will get back to you on that. I have a few websites that will help you get the pinout's

http://www.norotors.com/index.php?topic=3163.0
http://http://shbox.com/1/4th_gen_tech2.html#1995_pcm_wiring

lt1b4c

Basically Going off of shbox website of the pcm diagram for ignition, I came up with this. The part I have circled is a factory splice with two computer leads "both pink wires" coming out of of the splice and i'm guessing this is where they go on the pcm?

B30?
D3?

89rs454

Correct, That looks good.

89rs454

Here is a little jewl that helped me step by step, you have an 88 Camaro so does he http://www.camaroz28.com/forums/3rd-...ite-up-474185/

This has to be said this was made back in 06 lol these boys was getting it done 6 years ago. I had a few beers tonight just thought that was impressive. Cheers.

lt1b4c

Thanks man! really appreciate the help so far! Going to get back to working on it again this Thursday!

lt1b4c

Some before and after. Got the intake finally installed!

lt1b4c

Horrible night pictures but I got the fuel lines ran, along with my wiring harness installed.

89rs454

It looks great wow very clean, and tight. Keep us posted.