One of the most intimidating parts of doing an engine swap is the wiring... especially if it is a fuel injected engine. Because of this, there are serveral companies that specialize in making simple harnesses for fuel injection.

This post is just going to show you how easy it is to pull apart a stock wiring harness and make it ready for the swap. Pull all the extra wires out of the harness... and possibly reroute or remove systems from the harness.

I gleaned all my information from various shop manuals including factory manuals, Hayes manuals, Chilton Manuals, and a couple of online TBI circuit diagrams. One of the better diagrams I've found is the Hayes manual that had each circuit broken down. It made the approach I'm going to show much easy to understand.

If you wish to reproduce any/all of this, please give credit to me.

I'm going to have serveral posts covering each major circuit. A lot of the wiring of a TBI harness can be pulled out circuit by circuit... for example, you can pull the Idle Air Control circuit out of the harness completely. Some are somewhat tied together such as the MAP, water temp, and TPS sensors. In general, if all the wires in a circuit just goes straight to the ECM, all I will cover is the wire color and the ECM pin location. Otherwise, I'll give a little more info.

Before attempting to pull apart a harness, I would highly recommend get a copy of the schematic for your particular donor vehicle. There are some differences between various cars including smog circuits that I'm not going to cover and occasionally entirely different pin numbers.

When you pull a stock harness, you end up with something like this:
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224409&stc=1&d=1137205269

The first step in the process of cleaning up a stock harness is pulling all the wireloom and tape. You end up with something like:
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224410&stc=1&d=1137205269

Control is located on the side of the TBI unit.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224412&stc=1&d=1137205734
This circuit is composed of four wires:
Blue/black ECM pin C6
Blue/white ECM pin C5
green/black ECM pin C3
grean/white ECM pin C4

Injector circuit
Injectors are located on top of the TBI unit.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224415&stc=1&d=1137205825
This circuit is four wires:
Green ECM pin D14
blue ECM pin D16
red and white +12V in run

The red and white wires as you might notice in the picture above actually get tied together and turn into a pink/black wire. This wire runs to the ECM pin A6 as well as powers the ESC circuit and finally has a pig tail that you would wire to a fused +12V circuit that is hot when running and starting. *NOTE* One common mistake is to route this circuit to a hot in run wire that actually is dead when cranking the engine. Double check the wire you are picking for this.


ESC circuit
The controller itself is usually mounted in the engine bay upon the firewall. The knock sensor is located on the engine block.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224416&stc=1&d=1137205825
This circuit is four wires:
black plug pin C to ECM pin B7
blue plug pin E to knock sensor
brown plug pin D to ECM pin D1 and to a ground lug
pink/green plug pin B to +12V (see note above)

This is located at the back of the engine of Chevy engines.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224417&stc=1&d=1137206006
This circuit is four wires:
white ECM pin D4
black/red ECM pin B3
purple/white ECM pin B5
tan/black ECM pin D5

The last wire, the tan/black wire, has a plug on it. This is disconnected when you set the time of your engine. Make sure you put this in an easy to access location.

http://www.pirate4x4.com/forum/attachment.php?attachmentid=224418&stc=1&d=1137206178
Water temp circuit
This is located at the front of the engine.
This has two wires to it:
yellow ECM pin C10
black ECM pin A11 as well as the TPS circuit

TPS circuit
This is located on the side of the TBI unit
This has three wires to it:
black ECM pin A11 as well as water temp circuit
dk blue ECM pin C13
gray ECM pin C14 as well as map circuit

MAP circuit
I've seen the MAP sensor located in two places: on the firewall usually, on the air cleaner for older S10s.
This has three wires to it:
gray ECM pin C14 as well as TPS circuit
green/black ECM pin C11
black/red ECM pin D2

This is located near the distributor.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224419&stc=1&d=1137206253
This has two external wires:
pink this is a +12V hot in run and crank wire
white this is the tach led

It also has a two wire jumper that goes between the coil and distributor. See picture.

This is located under the driverside dash.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224420&stc=1&d=1137206296
orange/black pin E ECM pin A8 serial data
white/black pin B ECM pin A9 Diagnotistic test
black/white pin A ECM pin A12 and ground system ground
tan/black pin F ECM pin A7 700R4 ground
brown pin C ECM pin C2 EAC solinoid
brown/white (unknown wire at this time)

This is basically all the left over wires from pulling the wire harness apart.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224421&stc=1&d=1137206395
ECM pin A1 green/white fuel pump relay drive... plug pin D
ECM pin A5 brown/white service engine soon light +12V on other side of light
ECM pin A7 tan/black ALDL pin F
ECM pin A8 orange/black ALDL pin E
ECM pin A9 white/black ALDL pin B
ECM pin A10 brown Vehicle speed sensor input from buffer or aftermarket unit
ECM pin A12 black/white ground
ECM pin B1 orange +12V always hot.... tied into ECM pin C16
ECM pin B2 gray fuel pump signal +12V when fuel pump is going
ECM pin B8 green AC signal +12V when AC is on
ECM pin B10 orange/black park/neutral switch

Wires from pins A5, A8, A9, A10, and B10 actually integrate into the dash harness inside the cab. I cut these at the secondary wiring trunk while removing the TBI harness.

http://www.pirate4x4.com/forum/attachment.php?attachmentid=224422&stc=1&d=1137206464
ECM pin C7 light blue high gear switch (part of the 700R4 stuff I won't cover)
ECM pin C9 purple starter signal... usually attatched to the starter lug
ECM pin C16 orange +12V always hot... tied into ECM pin B1
ECM pin D7 purple oxygen sensor
ECM pin D6 brown ground

http://www.pirate4x4.com/forum/attachment.php?attachmentid=224423&stc=1&d=1137206525

This is what the semi finished harness looks like. If I were taking this to completion, I would have been doing the wiring on the rig and cutting some of the wires back to ensure a proper length finish. It would also be fully taped at all junctions and have wireloom the full length.

At the time of this writing, I am not ready to install the harness so this will be the finished harness picture for now. Also, this harness displayed is not going to be the harness I will be using. It was done while waiting to ship it off for someone else to finish up for their rig:D

Things to note:
Not all TBI systems have the ESC/knock sensor circuit. Most notable of these is some of the 454 TBIs.

I did not show the 700R4 related wiring that is included in many wiring harnesses. This is because not everybody uses the 700R4 as well as the fact that some harnesses are for manual trannies and like the above mentioned 454 TBI, some were wired for the TH400.

I spent several hours pulling this harness, stripping it, and reassembling it:
2 hours to pull it from the donor rig(an Astro van) which I'd never done before
30 minutes or so to pull all the loom/tape and extra wires that fell out(ie main starter wire, alternator related wires, etc)
3-4 hours to trace wires and pull them from the ECM plug
A lot of the above 3-4 hours was the result of taking pictures and writing some notes for this article. Realistically, a harness could be pulled apart in half the time if not closer to one hour.

Still doesn't look finished to me. Personally, I won't spend 5+ hours working on an old dirty, greasy harness. I prefer to purchase a harness that is already complete. All wiring and connectors, tape and looming are brand new.
I know a lot of people cannot afford to buy one, but like I said, my opinion. Good info though.

Still doesn't look finished to me.
As I said... it is mostly finished... there are a few odds and ends left to it that I will not do on the pictured harness because it isn't going into my rig.:D The odds and ends are things like the ALDL wiring, putting a lug on the starter wire, power wires(3 of them), and fuel pump relay wiring. I also did not wrap some of the circuits together because not everyone is going to place their ESC, MAP, etc in the same location.

I will update that picture with a fully completed and loomed harness that I'll be using on my rig. Unfortunately(or fortunately), my own wire harness will be a bit different due to the physical location of stuff on a Cady 472 as well as different equipment(coil integrated distributor) along with more things removed(no ESC):D

Personally, I won't spend 5+ hours working on an old dirty, greasy harness.
As mentioned in my final post there, most of that time was so I could take pictures for this article as well as my first attempt at pulling a harness from an Astro van. The astro van was a bigger pain in the ass than I thought. If it was a Camaro, I would have had it out in 30 minutes. An astro van would probably take me closer to an hour. And usually, I can whip a harness into shape in around an hour.

I prefer to purchase a harness that is already complete. All wiring and connectors, tape and looming are brand new.

As the saying says, time or money :P But I hear you on the new harness.

However, the last new harness I played with was a Painless and it was anything but... and it also didn't have any new loom to it. Plus the "minor" issue of about 2 feet extra of wire at the ECM :) Add to that the "forced" location of stuff(I got fucked at the ref because he couldn't get to the distrib disconnect easily because of where painless put it) as well as "forced" purchase of their plug version of stuff(TPS for example), I dropped it and went to a reworked harness.

If I had the money/desire, I'd actually wire my own harness with new parts so I could ensure that things end up where I want them rather than where a company thinks they shoud go. But I'm picky like that.

I'm right in the middle of putting a 4.3 from a 90 Astro in my toyota based truggy. This comes in real handy for me. I'm going to use a th350 instead of the 700r4 (already have both) so I won't be using any of the 700 stuff. What about the smog stuff, like the EGR, do you just leave that stuff completely out all the way to the computer plug ? I plan on getting a chip with that turned off.

What about the smog stuff, like the EGR, do you just leave that stuff completely out all the way to the computer plug ? I plan on getting a chip with that turned off.

Yeah... basically, any circuit I'm not using, I pull completely out. Including the pin at the ECM.

The EGR circuit consists of two wires a pink/black power wire and a gray wire that goes to A4 at the ECM.

Basically, when I am wiring my truck with fuel injection, I try to keep the EFI harness completely seperate from the body harness. To that effort, I will run wires in the same loom but not taped together.

Wow, thanks for all the time and effort! This will help out so much... So the wiring you have showed above, are the wires that will alow the TBI to run without problems? Is there a bunch of others usless wires that are on this harness stock? Thanks again!

very nice write up, got one for a tpi ?

nice writeup

What method have you been using to pull the pin from the connector at the ECM? I like this idea, but haven't spent enough time in seeing what's involved in doing so.

Twistedmods,
Depending upon the ECM, that is all that is needed to get a TBI to run.

The things I didn't show are: EGR circuit, 700R4 circuit, and smog pump related circuits.

echos,
Nothing for a TPI... I've never done a swap for one. But the process would be the same and many of the circuits are the same. The big difference would be in the injectors.

BlueJeep,
There is actually a tool for doing this. However, I have been using one of the micro screwdrivers to pull them. If you put the screwdriver through the top hole of each pin(ie the side the plugs into the ECM), you end up unlocking them. While looking at the ECM side, you should notice the pin at the top of the hole is biased one side.

Awsome write up Lil'John. I finished my TBI swap using a camaro harness last year and can fully respect the actual work in the pics.

My harness used an IAT (Intake Air Temp) sensor that simply plugs into the air filter housing.

As other who have done it them selves I learned alot about it. I chose to integrate factory relays for my fuel pump and fan. I ran wires for the factory guage sending units for future use. I also reused the fuse block to upgrade the old CJ dash harness.

Just to mention to others reading this..GROUNDS !!!! make sure you have adiquate grounds, if your tearing into a factory harness you can see there are alot. You can't have too many grounds.

Personally im glad i didnt waste the money on a nice and clean boughten harness...

:beer:

Hey lil'john. I found this tbi site. It shows the year and ecm's models with different wireing harness prints. I now some guys have a hard time finding them. Wheres a link to it.

http://www.chevythunder.com/gm_throttle_body_injection_pg_1.htm

Ah... the FSM grid sheet. Trying to trace wires on the FSM is a bit problematic. I've been partial to Chilton or Hayes since they tend to break down the whole car's circuits into a little more directly related items.

Unfortunately, trying to highlight circuits on a grid for this post would be a bit of a losing prospect for me for several reasons:
1) The minimum to run a TBI system varies based upon the TBI computer as well as if it is programmed. One can remove a LOT of the circuits from a TBI system once it is programmed.
2) As mentioned in 1, there are serveral different versions of TBI computers beyond the famous 7747. For example, the 5.0L TBI from a Camaro has three circuits that I didn't find on the Astro Van 4.3L TBI: air temp sensor, and two smog pump related switches.
3) There are also lots of variations within the 7747 class of TBIs. For example, there are three trannies possible that have different wiring requirements: manual, 700R4, and TH400.
4) Even more so, there are variations within 7747s of the same engine type. For example, the 454 TBI is found with and without the ESC/knock circuit.

What I have covered above is generally what a TBI system requires to run. However, if you want smog legal running in CA, you need all the circuits that were originally on the engine; smog pump, EGR, and all.

Man i just want to say AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA! My brain hurts. #hrs into pulling mine apart. Im lost. :confused:



WELL GOT IT ALL WORKED OUT. It took me a well but its cut down.

One thing im kinda iffy on is the AB plug circuit. Do all of them get used like the fuel relay. Do i need it. Im going to run my yota fuel setup on my tbi.

ECM pin A1 green/white fuel pump relay drive... plug pin D
DO I NEED IT. iM USING THE FATORY FUEL SETUP.

ECM pin A5 brown/white service engine soon light +12V on other side of light

WHAT DO ALL OF THESE PLUG INTO.
ECM pin A7 tan/black ALDL pin F
ECM pin A8 orange/black ALDL pin E
ECM pin A9 white/black ALDL pin B

ECM pin A10 brown Vehicle speed sensor input from buffer or aftermarket unit
ECM pin A12 black/white ground
ECM pin B1 orange +12V always hot.... tied into ECM pin C16

ECM pin B2 gray fuel pump signal +12V when fuel pump is going
DOES THIS ONE GO TO THE PUMP OR DOES IT SEND A SIGNAIL TO THE ECM

ECM pin B8 green AC signal +12V when AC is on
ECM pin B10 orange/black park/neutral switch
I HAVE NO NEED FOR THESE

Wires from pins A5, A8, A9, A10, and B10 actually integrate into the dash harness inside the cab. I cut these at the secondary wiring trunk while removing the TBI harness.

I dont know what to do with the 700r4 stuff. Im going to run it but im think about a manual value body in mine. It"s a trail rig only so fuck it.


LiL'John thanks for the write up. It helped me out alot. If i had to go by a harness grid sheet. Id problem bought one instead of working my way through it. Thank"S again.Kerry

The AB and CD plugs are the ones into the ECM.

The one row you found with an A1 is pins A1-12... the other row of the same plug is B1-12.

The one row you found with a C1 is pins C1-16... the other row of the same plug is D1-16.

Hopefuly this is the last ? about the harness.
First one:
I think you got the tps cicuit labaled wrong. The dk blue wire sould be pin C13 not A13.

Second one:
What the different in the A1 pin and the B2 pin. There both for the fuel pump. A1 says relay drive pin D whats this mean. And B2 says +12v when fuel is going.

Third one:
Is I have one plug not plugged in on the motor i dont know what it is. But on mine its bolt to the map cicuit. One grid im looking at for refrences it says ivrv. Any idea on this. The wires run to pin A4/A6 and a bl/white ground wires. It has alto of vacum hoses run to it.

1) you are right... fixed it in the post. Not enough coffee ;)

2) This is a "simple" one to explain ;) The dark green wire at ECM pin A1 is what goes to the fuel pump relay and turn it on. When I say pin D, that is the pin location on the fuel pump relay.

The tan/white wire at ECM pin B2 is what tells the ECM that the fuel pump is actually going. This wire also goes to the oil pressure switch, the fuel pump, and the fuel pump relay at pin E.

3) Hmmm... I've got two sources I'm looking at. My Camaro specific system lists pin A4 as the EGR solenoid(5.0L TBI). The other one lists it as EGR(4.3L and 5.0L TBIs) or as a EVRV solenoid. From a google search(http://www.megspace.com/cars/16147060/egr_sys.html), EVRV is just a type of EGR system (Electronic Vacuum Regulator Valve)

Thanks that help out alot. ill sya some of the yota guys how i sould huck up the fuel pump wires.
On the last question/ It's a EVRV. Mines hard to read. Think i need it pluged in. THis motor does have a different cam in it.

Thanks for the write up. It help alot.

Lil John, I'm almost ready to fire up my truck after 1 month of converting to TBI. I used a stock harness from an '89 sub. 1977 blazer, 350/350.

I have two wires I cannot find a purpose for: 1 a tan/black that feeds from the engine harness to the firewall bulkhead connector at the fuse block. I don't think this is part of the "set timing" circuit - everything I see for it shows that circuit as a direct link from dizzy to the ECM. I'm hoping its one from the circuit to control the 700R4.

2. The brown wire that goes to the ALDL - I think it connects in by the ECM in the glove box.

Any ideas?

Ramrock,
The EVRV is simply a fancy computer controlled EGR valve. If it isn't hooked up, I'm sure you will get an EGR code... unless you have a chip burned that doesn't have the EGR functions in it.

mouse,
1) What type of transmission was in the Suburban? If it was a manual tranny, that is the shift light ;) Which given your description, makes sense. If it was a TH400, it would actually head toward a relay... and it would be part of the downshift circuit. If it was a 700R4, it would be going down toward the tranny as well as going toward the ALDL.

I have that brown wire listed above as "brown pin C ECM pin C2 EAC solinoid" It is a smog related item near the smog pump if I recall right.

It had a 700r4. The blazer roared to life with the TBI for the first time tonight. The timing set as it should when I disconnected the tan/black wire. The computer then regained control when hooked back up.

excellent data ~ thanks

Still doesn't look finished to me. Personally, I won't spend 5+ hours working on an old dirty, greasy harness. I prefer to purchase a harness that is already complete. All wiring and connectors, tape and looming are brand new.
I know a lot of people cannot afford to buy one, but like I said, my opinion. Good info though.

Basically, what you are saying is you will pay money for something that does not function as good as the factory stuff? Those companies that make wiring "Painless" tend to remove and ground things they think are not needed.

It really does not take long to separate the wiring as he's shown. Actually, I have done this several times and now all I do is remove the Alternator wiring, oil pressure sending unit (not to confuse with oil pressure switch) and temp sending unit (again, not to be confused with temp switch) and you now have a "simplified" harness. I do not take mine completely apart like shown, In fact, once I remove the factory harness cover and tape, I tape over the harness every so often to keep the wiring in the same loom routing - then remove the wiring not needed.

By doing what the original poster has said, you are making this harness a "stand alone" system, thus "Painless" to deal with troubleshooting later.

I haven't messed with a TBI harness before, but am planning on here this week. If I remove a harness from a 4.3 TBI motor, including the injectors, with these flow enough fuel to be used on a non TBI 350 ?

If I recall right, the TBI units physically are the same between the 4.3L, 5.0L, and 5.7L engines... however, the injectors themselves are different between all three.

So while it might fire up, it would most certainly run lean. You can get a 5.7L TBI unit off ebay for around $50 any day of the week. From there, you can get a 5.7L ECM or get a chip burned for the 4.3L ECM... the harness I worked above was from an astro van and the ECM was one of the 7747s.

sweet thread...
I'm going the same route but installing it on a 300 inline ford - there is a guide here on how to retain the 7 or 8 pin GM module with an electronic pickup distributor (duraspark or the 4 pin HEI or the chrysler crap) I think it would be pretty neat to have the ECM control ignition timing and advances at the different RPM ranges and detect knocks and retard etc..
There is a sweet forum over at http://www.binderbulletin.org/forums/forumdisplay.php?f=75 that has a TON of information

How did you go about wiring the starter? I traced my starter wire back to the ECU which it ran into it. Is there a way to just run it out of the ignition where the key is? I hate wiring ahhh

does anyone know where the crank input wire goes to when it comes out of the ECM???

youngguns4x4,
You can wire the starter crank input to anywhere along the wire going from the ignition to the starter.

It is usually easier to just put a lug and wire it to the starter.

I haven't looked at the ignition side to see how it is wired there. I might look into it on my current project.

cobra56889,
Do you mean the starter crank signal? If so, see above. If not, what wire?

http://www.efitune.com/manuals/ I have most of the diagrams here

Thanks man!
I haven't even got to my engine rebuild or wiring yet for my K5, but I know you just helped my ass out LOTS!
Great post!:cool2:

What kind of problems will I have if I dont have a vss hooked up? I will eventually be running one when I swap trannies, but I just want to get it running right now. Also, do I need the vss buffer or can I just hook one side of the vss to the computer and the other to ground or power?

have a question. I ripped into a 89 stock wiring harness this weekend. And well I can't figure out a purple with white tracer wire in the harness. It says in the Haynes manual that it goes to the tach...however there are 2 of these wires in the harness,but only one showed in the manual. One does go to the tach and the other went to the firewall/dash wires. Does this get used?

Another is the starter crank sensor wire for the computer. You said it was purple. I did not hook any wire to the starter other than the key start circuit and the injection runs fine. Is it tied in somewhare else in the harness?

Wires I kooked up are

Orange 12v hot all time

Pink/black tracer 12v key start and run

Tan/blk tracer to fuel pump

I removed the egr circuit and the oil pressure circuit

I did not entirelly dissassemble the harness. Just removed the wire loom and started removing the circuits I knew I did not need. I did not even pull the pins from the computer plugs.

nice wriete up, ill hav eto read this a few more tiems befor i start to wire up my tbi/v8 swap going into my fj!......

The tach wire is the 14g white wire that comes from the coil plug. The other 14g wire is a pink that is hot in run and while cranking.

I've seen the crank wire (purple) hooked up higher near the steering column. But it is just as easy to put a lug on the wire and do it to the starter. I believe the crank sensor gives the engine a bit of extra gas while starting.

As for pulling the pins from the ECM plug, that isn't something I normally do... but for this article, I did it to demonstrate that the circuits of a harness can be broken down very easily.

thanks!

Just a quick update to give props to Lil John. My truck has run flawlessly since converting to TBI. It even tolerates the 85.5 octane fuel around here - but prefers the better stuff. Converting a stock harness isn't for everyone, but those who can, will save a ton of $$. Plus, GM engineered the wiring with quality wire and connectors. If someone hasn't cut it up, it is a nice quality product to use.

Did this late this winter with help from this thread,others on here, and an s10 manual.
Just wanted to say thanks and bump this back up.
4.3 swapped into my CJ using all the stock s10 harness culled down like Lil John did worked out really well.

:Cheers:

So what wires, besides the one going from the ECM to the ALDL, VSS, TCC lockup, etc. were kept from the interior harness. How many wires were kept from the firewall plug? I`m wanting to make this a "standalone harness" as you did, and fuse whats necessary on an aftermart wiring harness/fuse block.

I got my harness from an 89 Suburban if it matters, and it`s going onto a 82 350, with the sensors and TB from a 90 350, onto a truck with an 82 cab.

I have pretty much everything for the harness, motor/ecm related, and the junction block/fuseblock, and all the underdash wiring.

Any help is appreciated, and thanks in advance!

TTT! So what evers left from the AB and CD plugs on the ECM is all that shoulf be left when making this a "stand alone" system?

What`s the reason for removing the alternator wires, water temp and oil pressure circuits?

Do you have a list of what wires needed to be fused, such as the fuel pump, etc?

TIA!

You may find more answers clicking on the link to the binderbulletin that was given.

Go to the injection forum and then read the FAQ's.
They are all laid out step by step.

I HAVE A 92 CHEVY 4.3 IT HAD A 5speed IN IT & I PUT A 700R BACK IN
DO YOU KNW IF I CAN TIE INTO MY ECM TO HOOK UP THE 700R OR DO I NEED A DIFF. ECM ???? AND WILL IT SHIFT WITH THE WIRES UN HOOKED?

Great info in here.
I'm in the middle of converting my Nissan to a 4.3 V6 TBI and have the wiring laying on the table with a few questions still open.
I have a white 12 pin plug which I assume to be the ALDL connector but somehow I miss a part of the loom which connects to the speed sensor buffer. The VSS goes directly into the white 12 pin connector and stops there ?

Btt

Patrol,
The ADLD looks like:
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224420&stc=1&d=1137206296

From what I recall, in stock configuration, the VSS pair of wires go to the guage cluster area then feed into the ECM... I believe to the DRAC module:confused:

The aftermarket VSS's available out there get wired directly to the ECM.

Ah ok, now I see.
There's something missing in my wiring harness. My wiring stops at a square white 12 pin plug. Guess the harness from there to the DRAC is missing:mad3:

What's the best way to free the wires from the resin GM uses at the firewall bulkhead? It took me 30 minutes just to peel the 2 halves of the plastic shell apart! Can it just be heated or will a solvent break it down?

Thanks!

I used a hair drier and a knife.

Basically, heat the hell out of an area, grab wire, and pull wire out of goop. When goop is too deep, use knife to cut goop back and repeat:(

I HAVE A 92 CHEVY 4.3 IT HAD A 5speed IN IT & I PUT A 700R BACK IN
DO YOU KNW IF I CAN TIE INTO MY ECM TO HOOK UP THE 700R OR DO I NEED A DIFF. ECM ???? AND WILL IT SHIFT WITH THE WIRES UN HOOKED?

700R4 doesn't use a computer, just a TV kick down cable. It should run just fine.

Excellent thread Lil'John :beer:

Btt so I can find this later. Good thread.

Bumping an oldie but goodie for anyone doing winter projects.

Thank you sir, for taking the time to document this for everyones benefit. Quite helpful.

So is this the only sensors needed for a tbi to run. I have a complete tbi 350 (harness fuse block ecu) out of a 90 blazer that i plan on putting in a tacoma and want to make just a stand alone harness.

With this style of simplified wiring, do you need to have the stock computer reprogrammed/flashed, or will it still function with the stock setup. I have searched online, but have not been able to find any solid information.

This is located under the driverside dash.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=224420&stc=1&d=1137206296
orange/black pin E ECM pin A8 serial data
white/black pin B ECM pin A9 Diagnotistic test
black/white pin A ECM pin A12 and ground system ground
tan/black pin F ECM pin A7 700R4 ground
brown pin C ECM pin C2 EAC solinoid
brown/white (unknown wire at this time)


I pulled a 350 and it wiring out of a 94 chevy 1500 and putting it in my xj.. I will need to have it pass smog and the only wire I don't know what it does is a green one that comes out of this plug under the dash??

Bump this up tons of good stuff :smokin: