94PCM ... pins B28 and 29 are 5V ref. Is this 5V output from PCM, generated by pcm or do I have to put 5V on this?

 

Leave it alone, I never had to touch it. basically you need the 2 ignition and two power to the pcm, VSS output to your speedo, and relays. Oh and serial and ground if your doing any tuning.

I think the only wires i had to splice from the c100 were:

Ignition from c100 (PINK wire) to the pink wire on the coil

Reverse lights to reverse lights on tranny (T-56)

Oil pressure to the oil pressure sending unit (behind the intake)

Coolant temperature gauge to the engine coolant sensor (I
believe its between the #1 & #3 cylinders).

All power lines to power distribution

Engine ground to ground

Relays of course to PCM

Tachometer to Pink/Black wire on the coil

Starter to the starter wire on the LT1 C100 or C105, its a thick purple wire on the lt1 harness.

Miscelaneous splices:

2 Fuel injector wires, one from c100 one from c105 (Both pink) on the lt1 harness to Hot when key is on for the injectors.

2 Ignition wires from the PCM (I forgot which they are, just check out a diagram, believe thier both pink also) To hot when key is on.

2 Power wires from PCM to power distribution (Check the diagrams, believe its B15 and B31).

VSS from PCM to vss wire inside the car

Serial data from PCM to ALDL port.

PCM ground from PCM to ALDL port.

Believe thats all of it, if I missed one let me know.

 

That about sums up what I have thought.. but I'm a little confused on

"Tachometer to Pink/Black wire on the coil "

I have a white tach wire I believe is from the pcm.. I'll have to check.. and I had a white wire which was tach on 89. originally came from coil of 89 and went to gauge I believe.. Is this wrong? I don't recall pnk/bk then again.. I'm not too sure on anything right now.. When I sleep I count wire colors not sheep..

 

oh btw pasky :hail:

u too TexasLT1 :hail:

 

Im not sure if you can get the reading from the PCM. I know what your talking about. But I know for sure you can get the tach reading for the pink/black wire next to the solid pink on the coil. Oh I also forgot one more splice. The alternator plug. I believe its brown (At least on my vehicle) from the thirdgen c100 and hooks up to the alternator plug.

 

will check it out.. See half my problem is that the connectors which go into the firewall on the 4th gen were cut off at the firewall.. so I'm left to guess, well a little more educated than that with the diagrams I've found in various places on this board..

 

http://shbox.com/1/1995_Z28_engine_harness_A4.jpg

Only thing that goes inside the car are the C220, C230, C210 and maybe the c100 and c105 in that picture, that should give you a rough idea of where those wires you got loose are coming from. You dont even need to take any from them except from the c105 and c100 on that picture for the 2 pink wires for the injectors and the thick purple wire from the starter. I just have mine all taped up in my engine bay dangling. As far as vats, I have a cable and just programmed it out.

 

I got the car to start.. 1.2 sec mind you since i don't have any rad hoses.. I somehow hotwired the vats unless the 94pcm i have doesn't have it.. What did you do for the AC? or are you using it? There are alot of wires for things my 89 AC doesn't have.. mind you I am using a 96 AC Comp.. but the 89 doesn't have an AC Evap Temp sensor for example..

 

I got my compressor there but havnt done anything as far as wiring it, im gonna wait ti'll I get the car painted and rolling. All I think you need is just to wire the relay, dont see what else you would need anything for.

 

I was just looking through all the diagrams and I see what you are talking about, if its the same thing. On the LT1 PCM diagram, A13 is a white wire to the instrument panel labeled Tach Output. I have to assume we could use this to drive the tach instead of coming straight off the coil. The 3rd gens pick the tach up straight off the coil, but 4th gens use the PCM to drive it. Unless our tachs have a different driver than the 4th gens, it should work by using the PCM output.

 

yeah.. that's the 1 i used.. don't know if I had any tach.. engine ran for only about 1 sec till I shut it down.. never though to look..

 

Guys need your help. Started my wiring and all i got done is the is the purple (A) wire from c210. tan (B), dk grn (K) c220 white conn.
white (D) c230 blue conn. I've been working from the c100 bulk head. i have the 91 service manual for my car but i don't under stand the wiring diagrams to save my life. I've been going by what you guys have done. I've also been taking pic's of every thing i've done. but i'm stuck now. you guys where talking about Serial data from PCM to ALDL port. PCM ground from PCM to ALDL port. where are these at? also Relays to PCM. which pink wires are you talking about (Ignition wires from the PCM To hot when key is on). 2 Power wires from PCM to power distribution the wire inside the car. where are B15 and B31 located? sorry for the long story but need help. i do have the c100 diagram in my book but all i could hook up was the four.

 

ALDL is the (12 or 16 pin?) connector under the driver side dash.

Ignition was a pink wire off my thirdgen c100 on my 91 v6.

LT1 PCM diagrams (scroll up a little for the pin outs to find b15 and b31, you'll also find which wires to splice into the relays) : http://shbox.com/1/4th_gen_tech2.html#1995_pcm_wiring

 

The way I wired mine up was to get the diagrams on he above link. Plus in the lt1 wiring for dummines sticky there is another with the pinouts for all 4 connectors to the pcm.. each set of diagrams have circuit #'s on em. use them for ref. I also used the equivilent set for my 89.. I took these to work, put them under my pillow at night, talked to them, for 2wks while I made myself understand them.. I picked out the wires that I didn't need.. like Traction control and automatic tranny stuff. and cut them out. When I was done I had some sensor wires, some AC stuff, and some power wires.. pink was usually 12V with key on. and Orange was usually Bat.. 12V all time. All I did was find these in the old harness.

On your 91, you will have unplugged 3 connectors under the dash in order to remove your old harness, 2 are the computer and are ref as A,B,C,D connectors... the other is a connector for some of the inside wiring that has to go outside.. some sensors, vats etc... I don't have a diagram of that connector so I am having fun there..

 

Sounds like you had a pretty good plan to go about it. What you are doing is pretty much what we did for mine. We isolated the wires in each group that we knew we didn't need or that we knew wouldn't get connected to the new harness. From there we just compared diagrams and connected wires that had the same function. We didn't have the underdash connector diagram either, I believe, so it was just kind of pick and choose till we found the right ones.

 

pasky on that B15 and B31 i checked out the connectors on that diagram and the org wire that comes out at c210 plug is this the same wire? if so can't i use it instead of splicing from pcm? the reason i ask is i've been to alot of different post and none have mention of splicing into pcm. i just want to get the main wires hooked up. all i got is the coolant,tach,oil pressure and starter solenoid. thanks

 

yup, the orange wire on the c210 is the two power lines from the PCM.

 

Yall are lucky then. Whe I got my engine, the harness had apparently been cut anywhere it connected to the chassis or went throught the firewall. I didn't have any of the C100, C210 etc. connectors on my harness anywhere. I guess I didn't realize everyone else was getting those on their harnesses. Makes it a little easier to wire everything in.

 

I too had my connectors cut. Luckily I guess I had purchased a harness which was supposed to be 94 but was 93, and it had all the conenctors and the wires were the same color.. so I could ref my 96 harness to that..

 

Wow, that's not very far off from the LS1 harness I just got done reworking. Same connector #s and everything. The LS1 had an extra connector C101 up near C100 and C105, some other minor differences, but not off by much.

Swapping an LS1 doesn't look much harder than an LT1.

 

After doing an lt1 swap, i really dont think it is other than making room for the coil packs. I think i'll do an ls1 next soon as I pick up a junker thirdgen to rebuild. But that will be later down the road, for now my lt1 will have more than enough power for me. Also, LS1 is obd II (ewwwe).

 

pasky got another question c105 (B) pnk power feed from engine sensor fuse 10 is this the one your talking about that goes with c100 (a) power feed from injectors fuse 9? because you have 2 pnk injector wires on the post one on c105 and one on c100. i only show one on c100 for injectors. the other that i show on c100 is (G) pnk power feed from ignition fuse 11 OBD11. and if it is connect them all to ignition?

 

z91, which diagram are you looking at? nevermind, I think I just found it. From what I see we've got two different diagrams.

This one shows the injectors getting power through the C100 connector, while this one shows one through C100 and the other through C105. It doesn't really matter though, because they should all connect to Ignition. Everything you asked about you only want on when the key is on.

 

Thanks TexasLT1 just wanted to make sure my lt1 is a 96. The posting i'v seen so far have been for 93,94 and 95. Don't know how much difference there is between them. The pink coming out of my car (c100) goes to the coil.

 

OBD II could be different, i had a pink wire on each.

 

What is OBDII any way?

 

Was basically a new PCM software that uses encryption for the PCM Data and added a lot of new features, im not too familiar with it, so if someone else would like to step in here....

 

i used a 96 harness and a 94 pcm,and a set of 95 diagrams.. I'm doing ok.. so colors aren't a problem.. In fact I don't think I ran into any that were different. If I did, it wasn't a big issue.

 

Ok got another one dk green/white wire off my ecm going to fuel pump relay. dk green/white from white plug c220 goes connected striaght to fuel pump relay correct. also red (D) from c210 plug to fuel pump relay where?

 

Its looks to me like the dk green/white comes off the lt1 PCM, to the C220 and to the fuel pump. Just splice that with the corresponding wire on your fuel pump. You don't have to bother with the rest of them because your thirdgen harness already takes care of that. All that wire is for, is for the ecm to ground it and then the relay jumps and gives power to whatever it is relaying.

 

dk gr/wh off the fuel pump relay is the wire which the pcm uses to enable the pump.. I believe it grounds that wire. you will use that wire to connect to the pcm

 

Thanks How are both your swaps going?

 

85% done. need to do a little wiring.. hook up rad, and AC and throttle cable.. nothing too hard.

 

Thirim, you didn't happen to take any photos along the way did you? I could still use a lot of photos for the swap guide. Got anything I could use?

 

Engine is 100% complete here, idles smooth, temperature stays at a constanty 211 degrees with a single fan and no problems whatsoever anymore. Now its my t-56 im pissing about with. Just pulled it and installing new hydraulics and a spec III clutch.

 

no pics no camara.

on my list though... lol

 

Im too embarrassed to take pictures of my wiring lol, I need to tidy it up a bit, its pretty bad, .

 

mines not running.. but nice wiring.. and no camara. lol

 

texas lt1 i took picks of just about everything i'v done so far. took pics in today to get developed half of them anyway. i will let you know when i get them out. also i want to edit them. if my car doesn't start no pics lol

 

lol, awesome man, send me anything you've got

 

I got two wires off of the blue lt1 plug (c100) both going to fan relay. dk blue (h) and dk grn (j). My relay has brown to ign, orn to battery this is what my manual is showing. so where do these two wires go or do i leave them alone? also c220 white plug off of lt1 red wire (a) generator feed to instrument cluster no ifo on that.

 

Mine looks real messy too but Ill clean it up when i'm done. where did you guys put the pcm. It seems like theres no where to put it.

 

1. fan relays. of the 2 wires u mentioned, 1 is the trigger for primary the other for secondary. I don't have prints in front of me..

2. I mounted my computer in the pass side where the evap can was. I will have to lengthen the harness by about 6-8 inches to do this.. but there is not where to mount it.
3. generator feed.. im lost on that 1 as well.

 

this is the wire i'm talking about A red
http://shbox.com/1/C220_1996.jpg
this the one is for the cooling fan http://shbox.com/1/C100_1996.jpg

 

As far as I know thats going to supply one source of power to the guage cluster as well as probably the Voltage guage.

 

Dk Blue is A10 Secondary Fan
Dk Green is A11 Primary Fan.

I didn't hook up the wire from the alt yet.. and I doubt if I need it. Because I have power on my gauges and the volt gauge works.

 

http://www.thirdgenfbodies.com/forum...?showtopic=436

Thank You TransAM#5 :hail:

these are the diagrams I used, as well as some of the diagrams from the lt1 wiring sticky they seem to work 99% time for me.

search my name.. you'll find lots of my questions..

 

Are you talking about the small single wire going into the plug in the alternator? Yes, you have to connect that, it tells the alternator to turn on. In the thirdgens, a brown wire goes from the alternator to G8 in the C100 plug. On the 4th gens, its a red wire that goes into the same place, but there is a 470 ohm resistance on the wire.

Does anyone know for sure if the resistor is necessary or not? I know some people have had problems with overcharging but I don't remember how it was solved.

 

Mines working fine, no resistor and charging 13.9 volts.

 

pasky did you wire the brown from 3rd gen to red of 4th?