Can anyone direct me to a thread that explains pinning out a harness and how to create a custom harness? I am trying to install the motor and dash from a 04 gto into a 69 firebird and have the complete harness from the gto including bcm and ecm. Clearly I don't need things like ABS and VATS but I do want to make the harness work with the car. I am trying to understand how to eliminate this stuff and still make things like the cruise control and sensors work. I have never done anything like this before so I don't even have the most basic of information at this point. I do have the wiring the modules and a service manual though

 

Best bet for something this involved would be to get a license for ALLDATA DIY for the GTO. I think its around $50 for the single license. If you need other specifics let me know.

Jon
PSI

 

Here is a link to the PCM pinouts. As said above alldata is the cheapest option for a 1 year subscription to your first vehicle is 26.95, almost as cheap as the parts store manual!

Remember on the GTO sometimes the color coding on your harness might not match the schematic, I have had my hands on several of these harnesses and they are the worst for variation.

http://chevythunder.com/2004_gto_pcm_pinouts.htm

 

What I am not completely understanding is what is ' pinning out " ? Am I removing wires, crossing wires combining points of contact etc. I am kinda guessing pinning out is essentially removing wires that are not required for the harness/engine combo to function. so if i say need to " pin out" the ABS, do i find the pin out and completely remove the wire? and how does the computer understand that it isn't needed anymore? In my overstressed mind pinning out is is the same as not plugging the plug in or just clipping the wires and taping em up. Sorry if i sound completely retarded on this subject but this was never something I really wanted to understand, but cost and desire finally overcame fear of the mysterious electrical systems employed by new style cars.

 

'Pinning Out' means that you are keeping and removing the wires that need to be used for the engine and transmission to run in a non-factory application. Remember, in the original application, the engine and transmission wiring were not only intertwined with many body and chassis controls, the lengths were made for the factory application. In your case, some of the wiring is not going to be needed, in which case you can remove that wiring from the harness (I would advise not clipping the wiring). More importantly, connecting power and ground to where it needs to go is going to allow the engine and transmission as well as the GTO DASH (Which I thought during a previous conversation you said you were going to use) to work properly. Additionally, you will need to program the PCM to remove the items that you wont be using in your conversion.

I would start with the manuals. Either you can get them from the link above, LT1 SWAP, or the service manual/alldata. Print the pages out and go through all the items that you want to use. As you are going through the manuals look at the harness and label everything. From there you can eliminate what you dont need and keep track of what needs power and what needs to be grounded. If you have to lengthen wiring or shorten it you can do it at this time.

If you have questions ask on the board, there are plenty of people on here with a ton of experience. I know that there are more brute force methods to doing this, but I feel it becomes less overwhelming when you follow a structured approach. Hope this helps.

Jon
PSI

 

1. Find the pin# you will not use/need
2. Trace wires to the red/blue or green/blue pcm connectors etc.
3. Find the pin# on the connector and lift up the tab and push the pin out.
4. Pull the pin and wire completely out of the harness
5. I Found some things are so tangled up I had to cut the wire(might not be same for you, so that would be a + for no cutting), but wait. Trace the wire and pin all the way to whatever connector it leads to. Cut the wire about 6in or so from the connector. So if you need to for whatever reason, you can solder/properly crimp the wire back into the harness and push the pin back into the pcm connector if you really needed to.
6.When you remove the wire and connector label them both with tape. Write down what PIN#, Which PCM connector, and what the wire was. Again for whatever reason you may or may not need to place the wire back into the harness. Now you know where the wire goes and what it was used for. Just push the pin back in and like I said solder or properly crimp the cut ends back together.

Removing the wires is really the easiest part. I first laid out my harness and figured out what each connector was. If I wasn't too sure then I traced the wires from the PCM connector by the pin# (which would tell me what it was) then follow it to the connector and label it from there.

After that removing wires was simple. Just be sure to label everything. If you go to cut anything label it first. If you cut some wires in half, then label both ends so you know those two go back together with each other etc. It will save your ***.

Ive never done a harness before but some masking tape and sharpie + all harness info that you can kind on the net and on here have made it a breeze. Had to sharpen up on my soldering skills but its not so bad. Just time consuming.

 

BOXCHEV is right on the mark, take your time and make sure to double check before you cut. I did my harness in a similar fashion, took about a week worth of evenings and lots of solder and heatshrink.

 

I went through this same thing on a 4th gen Camaro. First off you can decide to just leave the harness intact but it can be a bit overwhelming to do it that way. I decided to keep the car stealth mode so the interior looks very stock. What I did was go through each harness at a time starting with the motor harness then the engine bay then the body harness. The harnesses were then tied to older connectors/systems as needed. Each time I removed the harness then the wiring not needed then replaced it back into the car to make sure everything worked. When you do it this way you can pinpoint where you may have problems and work on each subsystem at a time. This also helps with other issues like the need to extend some wires, etc. It also helps dictate where some of the systems should go. Each harness was unwrapped completely and wires were removed completely. Some wires are tied and will need to be cut to leave the wires connected to intact. When rewrapping each harness the systems were split off to give as much freedom as possible for movement. The process can be time consuming but it is well worth it over grafting it to an original harness. Suprisingly the harness fits very well from a 4th gen into a first gen with little or no wiring extensions other than relocating the PCM which required extending all the PCM wires. Basically I kept everything that I could use and removed what was not needed here is a list of what was removed:

EGR
ABS
Power window wiring at the BCM
Torque management
Air Pump
Air bags

Systems kept:

Cruise control
Evap system
Both O2 sensor wires. The second bank is used to log the WB readings.
A/C, heater, fans, etc
Fuse blocks
Wipers
Driving lights
Headlight system
BCM for power locks, trunk, and alarm system
Dash for separate gauges and warning systems, blinkers

Systems rewired:

Defrost circuit as a separate power for a amp
Stereo - rewired to run down the drivers side and accomidate speakers, etc

Shoot me a PM with your email and I can give you a spreadsheet that I created as I did my car which should help you a lot.

 

Thanks guys, it is starting to make a bunch more sense now. Jon you are correct I still have plans on using all the GTO dash and such. I suspect/hope not much will need to be pinned out with this project, but for sure abs and probably egr will infact be pinned out. Like I said it is starting to make more and more sense with everyone's help. Jon thanks again for taking the 30 or so minutes to yap with me about this project I really appreciate it bud!!!!!