I am trying to identify all of the connectors for my 1992 z28 305 TPI harness for an LT1 swap and wiring work.

I have the helminc manual but every picture that shows connectors gets cut off before it shows you where the connectors are on the harness itself. Its almost impossible to identify everything just by going by these pictures unless everything was marked when it was taken out of the car which it is not in my case.

Right now I have the the cars complete wiring separated into the engine compartment portion, the interior portion, tailights portion, front lighting portion.

ANyone know of a good way to do this that will not take forever such as checking each and every wire and connector individually by counting the number of wires in each connector and colors of each wire and then comparing to the connectors in the diagrams? This will def. take forever.

 

ok so i am going to try and work backwards and just eliminate wires and eventually connectors that I dont need.

Has anyone purchased a new harness for an LT1 and then reused their existing harness and mate the two together? I am wondering if it is best to do as I suggested or start somewhere else. I guess i wont hurt anything being going wire by wire from the C100 and see where it leads me. but i'd hate to hack it all up and then regret it ...

 

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

https://www.thirdgen.org/forums/post...009-post4.html

Post a pic of any connectors you're not sure of

I hope you havent started cutting up the 92 TPI harness, its worth a good bit. Find a 90-92 V6 or TBI harness to work with. It wont change anything in the end

 

Thanks Pocket. That helps a lot. How much would my harness be worth? I dont really care for making an extra buck or two at the cost of days of waiting for shipping and finding another harness and such. With all the money I spent on my build this harness will probably be one of the cheapest things i do lol...

Anyways I'll probably just use the harness I have because I dont want to waste anymore time. All of the wiring writeups I see are for people reusing existing harnesses. I bought a new wiring harness for the LTx swap (Photos attached) to only include connectors for stuff I am using - no ac, no emissions, and includes T-56 connectors for the auto to manual conversion.

One of the photos show the end of the harness that connects to the PCM, has the fan and fuel pump relays and individual wires for the ign, battery +, tach, speedo, etc...

I imagine I can just connect the autometer guages to these here right? and the power for the guages would go to IGN on or would it be constant 12v battery line? I think my job is so easy that im just not seeing it right lol
I am troubled on what I need to keep from my 3rd gen. I am using all new autometer guages. Any pointers?

 

Thats a full stand alone harness. See those wires with a butt connector on the end? Connect those and she runs

As for your stock harness, in your pic the big one laying in the middle is from your dash. Put it back intact. The engine half gets cut down. Read the 3rd gen prep thread for step by step instructions. You need the C100 and C207, all your splices will go to those two connectors

Anyways, a good 90-92 TPI harness goes for $180-250. Add $100-150 if it comes with the ECM. A 90-92 V6/TBI harness should set you back $0-80

 

I can see what you mean about the butt connectors/wires - those seem to just connect to all of my gauges. But what do you mean by the engine half gets cut down? - why would I need the engine half with the harness I bought new for the LT1?

The old engine harness connects to the C100 and C207. So can I just take out each wire of the C100 and C207 that I dont need? I dont see why I need to tear down the 305 engine harness.

The helm inc manual breaks all the harnesses down into 6 parts:

1 - front lights
2 - engine
3 - air conditioning
4 - instrument panel
5 - cross car
6 - rear lights

1 connects into the C100
2 connects into C100, C105, C207
3 connects into C100, C202, and harness 2 i think
4 connects C100, C208 (to harness 6), C207 and C202

3 I can get rid of, just hard as hell to identify
I think 1, 5 ,and 6 stay the same.
Cant I just scrap 2?
I modify 4 to accept the stand alone LTx harness correct?

 

The C100 is part of the TPI engine harness. I suggested selling it and finding a V6/TBI harness because the part you keep is universal between them. The C100 powers the entire dash harness, stock fuseblock and houses numerous gauge/fuse wires along with the fuel pump wire and a few bits for the airbag system

It also acts as a clamp holding the light harness side of the C100 into the socket

Nearly all of the old wires from the C100/C207 get reused, but yes you can delete some since you already have a fuseblock. The C100 is a major pain to repin so leave 12" or so of length, wrap the end and tuck it back in the loom when deleting a wire

The engine bay should have 4 separate harnesses, excluding small removable sections like the IAT/Dist mini-harnesses

1) Light harness
2) Main engine harness with ECM connectors starting at the C100, ending at the C207 taking up the bulk of the engine bay
3) HVAC, wraps around the box
4) cruise harness, drivers frame rail inside the sheath

The dash harness is the most complex part of the car, but info is sparse. Do not modify it unless you absolutely have to

After it, there are a few bleed off harnesses for interior options like dome light, power seats, power doors, tail lights etc

None of that stuff gets modified

http://www.fbodyrescue.com/forum/vie....php?f=34&t=78

Here are the pins worth noting, all of them located in the engine harness. They should encompass all of your butt connector splices

 

Thanks Pocket you rule. I am first going to outline the entire process on what to remove and what to splice and so on before I do anything and hopefully someone can shed light on that to see if it makes sense.

I'll keep you posted on where I stand after this weekend. I hope to make a guide while I am doing this for others to use who purchase stand along harnesses to add to the community of information.

 

Pocket - i took the online C100 and C207 pin diagrams and marked up what I think I can remove. Would you mind taking a look?

For the C100 I just crossed out the ones I probably dont need

For the C207 I circled the ones I would keep and crossed out the ones I can get rid of.

Can I just remove all of the unnecessary wires that I show crossed out? I will have no air bags or any such system, no wipers or washer fluid and no emissions stuff either.

 

I started to draw things out on paper first so I do things right. my stand along LTx harness that I purchased has the following:

General engine sensors and T-56 hook ups (this i will have to deal with later)

One grey wire goes to Fan #1
One Black wire goes to Fan #2

Set of wires go to fuse block from which two wires come out
One Red to positive for harness power
One Pink to IGN in run and "crank" - as labeled on the tag

Set of wires go to the 4 PCM connectors

Then there are two Fan relays and One fuel pump relay. I am running two fans but that kit came with its own relays and wiring. Where and how do i deal with this?

three wires go to ALDL connector - this just stay by itself correct? no splicing or connecting to anything?

then six individual wires for:
Gray - Fuel Pump Feed ++
White - to tach
Brown/Gray stripe - SES Light
Green/White stripe - Electric speedo 4000 PPM
Green - AC clutch on signal
Tan/White stripe - Oil pressure gauge breakout

do some of these go to C207 and some to C100 or all in one place?

 

If I understand this correctly - i strip down the 3rd gen engine side harness to basically nothing since I am not using any one of the old engine sensors because the new harness has all that. so I should be left with a couple wires from the C207 and C100 that should tie into the loose wires that I have with the new harness?

I leave the entire interior harness in tact and just connect the C207 and C100 back together? I would like to strip down the interior harness of as much useless crap as I can but i cannot find pin outs of how to identify each of the connectors and where they go to. Also what do I do with the 3rd gen fuse block?

i obviously need lots of help and none of this info is really clearly shown anywhere so i am really lost

 

This is what you strip the C100 down to



No splicing for the ALDL unless the stand alone harness doesnt have one. OBDI LT1 swaps can reuse the stock 3rd gen ALDL be connecting 2 wires at the C207

Fan 1/2 connections can be switched around, dont worry about color matching, all it gets down to is left or right turning on first

Red positive battery power goes to the ORN wire feeding the fuel pump relay AFTER the fuse

IGN goes to any of the old pink wires. The big coil wire is the most common, but you can use anything from emissions common to INJ fuse wires C100 F4 PNK

Fuel pump 12v feed means its already got a built in relay so you wont reuse your stocker. C100 G4 GRY

Tach is in the C100 D6 WHT

SES is more often known as MIL in the wiring diagrams. C207 C BRN/WHT

Speedo C207 D GRY V6/TPI, K BRN TBI

AC HVAC connector green wire. C105 IIRC, its black and funny shaped compared to the rest of the engine connectors

Oil C100 E5 TAN. Strange it includes the oil gauge wire because its not part of the engine control harness

This should help with the fans



You are correct. Fastest way is to cut the fender grommet free on both sides, cut the C207 off where it meets back with the ECM harness, and pull each wire back individually from the C100. Next, pull the HVAC connector free (3 wires) and the rest of the harness gets junked

I really suggest staying out of the dash harness unless you really have to go in there. Its not being difficult or anything. Its that info is scarce compared to engine wiring and the harness itself is rather particular to whatever option loadout the car had when it was built. Individual circuit diagrams exist, but they arent as helpful as youd like. Use this site to help, but know you're venturing into uncharted waters

http://www.austinthirdgen.org/index.php?pid=19

Original fuseblock stays put and doesnt get modified. It will still house the unused fuses, but several more non engine fuses will remain live. You can depin individual fuses, but under dash wiring isnt something that really needs to be trimmed down. Also be aware that several fuses have wierd dependents not even remotely related to the main function drawing from it. Removing the main function because it's not used any longer many have adverse effects that you wouldnt ever expect. EX: Courtesy lights also feed your speedo

Id recommend sticking to C100/C207 mods. Most people get sick of wiring even going that far

 

Thanks Pocket. Im probably getting annoying but i still dont get why I need to tear down the original 3rd gen engine side harness... I have the new stand alone which has everything I need so why do I bother with the engine side harness?

The interior harness connects to the engine side harness via the C100 and C207 so why not just hook up the wires from the new stand alone harness that are loose to the appropriate wires on the interior C100 and C207 connects? This will leave out any modifications to the C100 whatsoever. Make sense?

I know what you mean about scarce information for the interior harness. The service manual doesnt even identify what the pin outs for all the connectors are. No way to do this unless I start looking at electrical diagrams for various systems of the car... basically I just want to remove all of the air bag, radio, AC and any other heating vent wiring.

My car will have no heat, no ac, no vent, nothing. Radio will be aftermarket wired on its own and no safety restraint stuff.

I started to take apart the 3rd gen engine harness but it just didnt make sense to me as to why i needed to do it. Let me know if i am making sense here or do i have no hope lol...

 

Try to start the car, have working gauges/headlights/fuelpump/etc. without connecting to C100 and C207.

Try to connect to C100 and C207 without the engine side of the connectors.

Then you will understand why you need to harvest those two connectors from your old harness (or a junkyard V6 one).

 

Check out the C100 diagram above. Thats what you salvage from the original engine harness. Not a whole lot of that deals with engine functions or control. You're saving the power and gauges part of the harness which happens to be universal to all similar year harnesses regardless of engine type. In particular, the power wires A4 and G5 supply battery 12v to ALL of the cars electrical system. Absolutely nothing will work without these two wires connected to the battery

Sure you could located those wires in the dash harness and run them external, but whatever you did would be hardwired so you'd never be able to remove the engine harness from the car again. Plus theres the issue of tracking down those wires in the dash harness. Look for yourself, the main bundle is about 3x the size of the ECM bundle and 2/3 of the wires are red, pink or orange. Not something Id want to wade through again

 

Ok, i think I am getting it now. And the idea with all new aftermarket gauges is to hook them up to the C100 on the interior side so that the engine harness is still removable if need be? I know some of the guages hook directly to their sensors but I guess I could use empty ports in the C100 to run those through too.

I am going to strip the harness down today as you mentioned and see what I end up with and post it up here. I really appreciate all your time and effort in helping me. I should just have you come by one time for all answers and pay you but you are too far away

 

Ok, just got the 3rd gen engine harness torn down. See pics below. Pockets instructions are easy as hell to follow and was just scary at first but its really easy to see things come apart once you get started.

I am unsure of what the connectors on the bottom row of the second pic are for. I dont think I need these but if you know what they are and think I need to use them please let me know.

The third pic shows the fuel and fan relays and the C100 and the wiring I have left.

I checked the pinouts and labeled each wire. Please tell me if I am wrong about the following and I also have a few questions regarding a few of the wires:

I forget what the tan/white brake pressure sensor connector is for? Is it for the booster pump? I am having manual brake setup with no booster pump so if this is what its for I can get rid of it right?

the pink/blk for emissions A7 is going to be scrapped

the blk/white for supplemental inflatable rest. F8 can get scrapped to

the blk/white for engine C7 - what does this go to?

gry engine G4 fuel control goes to... ?

the prple E7 torque converter can be tossed cause i am running T-56

then tan oil pressure sensor gets cut out but the wire hooks up to the new oil pressure sensor i have with the stand alone harness

green F5 instrument coolant temp - the connector is really small on this. this is a secondary sensor for temp right? there is another coolant temp sensor in my pile of connectors

the two red wires for IGN and Fuse BLock power get wired directly to the battery? or to the starter or something else? Stupid question but do I have a power distribution block with the stock harness or is this just where I connect all the wires requiring power then connect them to battery or starter?

Pink F4 goes to ignition and the white D6 is the engine tach but stock setup has both these wires going to the IGN coil. how does this work exactly? I guess i cut the white from the sensor and hook it to the tach connector on the new stand alone harness and then the pink goes to the pink IGN connector on the stand alone harness.

My new fan setup came with its own relays and wiring so I need to look at that and the Aeromotive fuel system has its own relay and wiring as well. I'll have to take these out to see how to tie all this in but I can get rid of the factor relays for these correct?

Done for today, girlfriends gotta get some time now...

Thanks again for your help Pocket and anyone else who may be following along/helping

 

Glad the thread helped

Bottom row, left to right

Knock
IAC
IAT inline connector (TPI only)
O2
EGR
Secondary fan pressure override switch
Fan thermal switch (shouldnt be on a SD TPI)
Underhood light

Brake sensor is a warning for the dash dummy light. If your reservoir goes dry sucking air, the pressure will drop at the sensor and you get a light before you crash and explode. Helpful, I know. Delete it with a non stock master, you may have to pull the cluster and remove the dummy light

Emissions can go. I find it convenient to power my HO2s with this wire, but since your stand alone harness already has a fuseblock it serves no purpose

SIR ground can go, but be aware GM liked to tag non related things onto power/ground wires so scrapping it may kill other functions you didnt think of. Id keep the ground and delete the SIR system directly. Unplug the module on the pass side of the dash, IIRC only two fuse wires connect the dash harness to the SIR harness. There are 3 inertia sensors, one under the hood latch, one behind the radio, one behind the shifter. Rule of thumb, anything with yellow connectors, yellow tape or yellow loom is SIR/SRS related. This applies to all cars, GM or not and was mandated by the SAE

C7 is cluster ground. Your gauges use a redundant ground to the engine in addition to the questionable ground to the dash frame

G4 is the 12v wire feeding your fuel pump directly. Your stand alone harness already has the fuel relay built in, so connected the pump 12v wire to this directly. You can scrap the 3rd gen relay

Brake switch on E7 can go

Yes, cut the old oil sender wire and splice it with the stand alone harness connection

The small connector runs your gauge directly, just like the same sender has ran the analog gauges for the last 30 years. The 2 wire connector is for the CTS that goes to the ECM. It doesnt have anything to do with your gauge. Connect the small end to the sender in the cyl head of your LT1. IIRC its on the pass side between #6/#8 primaries

The two big red wires need to get connected directly to the battery some how. From the factory, they ganged on the starter lug. I absolutely despise this and move them to a more accessible location. A power dist block is anywhere multiple wires gang together to distribute whatever current/signal/ground across each equally. I prefer to use the late 90's S10 5 pole block with its fancy cover located on the pass outer frame rail near the battery. A v6/TBI battery cable fits the swap perfectly and easily reaches the block. Dont forget to run the alt output wire to this dist block as well

IGN and tach are correct, cut and splice

Use the stock fan relays or the aftermarkets, it makes no difference. A relay is a relay. Your stand alone harness will have 2 fan relay splices that are rather small gauge wiring. I refer to these as "call wires" because they call for the relay function when the specified conditions are met in the PCM. This should help

 

Thanks Pocket. I am running a wilwood master cylinder so then the brake pressure sensor will get tossed. My interior is completely stripped already and i am not using the stock gauges or anything so i'll either locate and remove the brake light wire or dunno, just let it hang out?

C7 is only needed if I reuse the stock gauge cluster. I am using all new autometer gauges so I dont really need it but I guess I might as well just ground it just in case the interior needs it else where.

Ok, so I got the power distribution block. Basically what you use when installing a stereo system too with subs and amps and such. I had used power distribution blocks for that. I can find something that looks nice.

I am really picky about making everything look clean and what not. I realllllly want to get into the interior harness. Tell me if I am wrong here... all the pins at the C100 and C207 from the engine side translate to the interior side so whichever wires from the engine side that go into the C100 and C207 come out on the interior side the same wire correct? So everything I delete on the engine side can get deleted on the interior side right? The interior harness is enormous and I want to toss all the emissions stuff and basically follow the same procedure for the 3rd gen harness prep but dont cut out any commons if there are and first get through all the air bag stuff. I think that will take out a good chunk of the wiring, then take out one by one the wiring not necessary as deteremined from what is removed from the C100 and the C207.

I know this is a scary procedure but there is a lot of stuff I do not care for or need. things like the door switch for dome lighting and such... dont care if the light comes on when the door is open. things like that I just want to get rid of all together and not have tons of useless wiring rolled up and tucked under the dash.

I am going to check out the fan and fuel system wiring I have and see how it all hooks up with what I have now.

What do I do with the C207 now?

 

Yes, the C100/C207 pins correlate to the same pinout front/rear, but be aware the dash side often has double wires going to most pins. This gets tricky to remove what you're not using

Id recommend identifying what you want to remove and leave the rest alone. You REALLY dont want to make a mistake and be troubleshooting a missing power wire in the dash harness

Id still keep the C207, maybe replace it with a different smaller inline connector, but leave some for of connector there so the harness can be removed at that end

 

Got it. Before I start cutting anything I think I will just take the large section of the plastic wire loom off and then try to look at how this can be done then I'll post it up here to see if it makes sense or if anyone has experience with some of these.

Also, both sides of my C100 at gooped up with a ton of some black sealant or something so its nearly impossible to trace which wires go where

 

It's connection grease to keep water out. Good info about it in here
https://www.thirdgen.org/forums/elec...ctor-info.html

 

finally got around to working on the harness again. everything is setup to be connected but have a few left that i dont know what to do with.

The brown wire from the C100 for coolant fan relay goes where? the stand along harness has two fan relays. So the coolant temp sensor will tell the PCM the temp then the PCM signals the fan relays to turn the fans on correct? So how the does brown C100 wire come into play?

my fans came with relays as well with 4 wires coming out of the relays to splice into somewhere but i dont need these because i already have 2 relays in the stand along harness. Fan wiring also comes with a connector to the fans from which one is for ground and the other is for fan positive which the diagrams it comes with says to splice to the fan relay. So the ground is easy and the red for each fan goes to each relay somehow. which wire on the relays do these go into? one relay has 4 wires - blue, black, pink, and red (fan #2). the fan #1 relay has 4 wires - grey (tagged as fan relay), green, red, pink.

The thicker purple wire on the C100 for the starter/charging system just goes to the starter correct?

Once this brown coolant fan wire is hooked up the C100 is taken care of.

I am still not sure what you mean with the directions you gave me for the C207. From one of your other posts which you posted a link for above you say the necessary pins for the C207 are:

Necessary pins
B Pnk/Blk INJ 12 fuse - where does this go?
C Brn/Wht MIL - this is SES light i believe you said before which i just connect to the stand along harness splice for SES
D Gry Speedo V6/TPI - what do i do with this?
E Wht/Blk ALDL B OBDI LTx swaps only - i have the ALDL in my stand along harness to this gets scrapped?
F Pnk/Blk PCM fuse - where does this go?
G Pnk/Blk INJ 2 fuse - where does this go?
H Tan/Blk ALDL M OBDI LTx swaps only - remove?
K Brn Speedo TBI only - remove?
N Orn/Blk P/Neutral switch - where does this go?

SOrry for all the bombarding questions but i would be grateful for more help Pocket, and anyone else as well

 

pocket i followed your instruction for the C207 on the other thread but posting back here to keep myself and other organized if this info is needed later... so i am left with only two connections to the C207 - SES and VSS. these need to be connected so you can use the factory gauge cluster correct?

because my stand alone harness has two wires for ses and vss - cant i just connect my autometer gauge to the vss and the ses light in the new cluster to the ses wire? i dont get why the entire C207 needs to be left if only these two wires need to be connected only.

Also, i need help identifying the following interior connectors. the helm inc manual doesnt help too much. i found a couple but still need a few more. i numbered them to make it easier to list:

(first photo)
1 - 3 pin rectangular connector behind the fuse block - what is this for?
2 - brown wire is for?
3 - black connector with two white wires going into an orange wire for?
4 - black connector with purple/white wire is for?

then moving to the rear of the car (second photo)
5 - ?
6 - ?
7 - ?
8 - ?
9 - ?
10 - ?

(third photo)
11 - looks like some kind of vacuum connection?

 

( first photo ) I disconnected this section of wiring from right behind where the radio/heat controls go in the console. looks like all speaker connections right? i am just tossing the entire section, if i shouldnt for some reason please let me know - using all aftermarket stereo stuff

(second photo)
12 - what is this light for?
13- ?
14 - ?
15 - two blue wires and blue connector?
16 - ?

(third Photo)
clarifies some of the connectors in the second photo
17 - ?
18 - ?

 

last photo

19 - 27?

thanks everyone for the help!

 

Gosh, the dash wiring gets confusing. Best bet for the unknowns is to look for similar shaped mating plugs. Remember that GM often wired the harness to support ALL options and simply didnt plug them in when the option wasnt ordered, so you may very well have a bunch of loose connectors

3-VATS key resistor from key
4-VATS resistor value to VATS module

Looks like the under seat/console wiring
5-LR speaker
6-Guessing some sort of console/shifter bulb
10-E-brake
Yellow tape/connector body means airbag related. Rest of the stuff should be under the console
11- Rear defroster
Cut wires fed the old fuel pump/sender
GRY pump 12v
BLK sender/pump GRD
PPL Sender to gauge

Cant say Ive ever seen that whole section of harness before. Keep it until the build is done and if no functions are unaccounted for then dump it

15-RR speaker
16-HVAC head unit
17-HVAC head unit
18-Auto shifter connector. Disassembled this for your auto to T56 conversion

Dont see 19-27

 

thanks pocket! you rule. forgot the last pic for 19-27... here it is..

 

19-25 are HVAC miniharness. These go back in the engine bay through a small hole behind the pass cyl head. Id suggest installing this before putting the motor in because its really tight

19-Blower fan
20-Heater core bypass valve
21-AC pressure cycling switch
22-Inline HVAC to engine harness connector
23-Blower fan hi speed relay
25-Manifold vacuum port feeding the HVAC ducting

24-Pass door open/close switch for dome light
27-Cruise control inline connector-Signal stalk to cruise module

Not sure for 26, looks like speaker stuff though

 

Thanks pocket. i am not using HVAC - no heat, not AC, nothing so all this can probably just get tucked away. i would cut it all out but like you said who knows what affect it may have on the rest of the wiring...

 

pocket did you see my post #24 regarding the C207. from readings your other posts it sounds like i only need the two wires for the C207. this is ONLY for reusing the stock guage cluster right? with new Autometer gauges wired up why do I need the C207 again? I cannot find a good explanation for this other than a couple people saying you need it period. but WHY?

also, any idea which kind of fuse to use from the alternator to the pwoer dist. (red wire?) i had the cut the factory one out.

thanks again for everything!

 

How has interior wire cleanup been going. I too hate a bunch of crap in car that I don't use or need. I just am not brave enough nor fully understand wiring yet to tackle it

 

I honestly havent had any time to touch the car in the past two months... very busy at work and just need the weekends to relax and redo bathrooms in the house. stuff never ends.

anyways, my plan was to lay the harness out and take off all the tape and plastic wrap and what not and just be down to bare wires then start tracing and picking useless stuff out and verifying it wont mess anything else up but right now i just want to the to run so last time i worked on it i just ended up labeling connectors i didnt need then taping them back and covering it up. all my wiring will be hidden behind the dash or under the console. Maybe one day if i have to tear out the interior again i will go through the process but now i want to finish the car. its been two years of working on it and just am loosing patience.

 

I hear you there