i posted this in the electronic section but figured a lot of guys here did this whole "race car wiring".............

Next on my build is my electronic section. I want to have the PCM a stand-alone unit for the engine and then hard wire the car for headlights, tail lights, turn signals etc. For the engine harness what all sensors do i NEED? Im running SD (boosted motor) and a 2-bar MAP. If i run open loop, or which ever doesnt use the o2's for referance, can i get rid of the o2 wires out of the harness? Also ill have autometer water, oil gauges so can i not run them sensors also or will it play games with the PCM? Basically i want to run the bare minimum wires and use the PCM as a stand-alone unit mounted inside the car. And will the PCM need anything from the body harness to work as well? Like anything from the gauge cluster? Sorry for all the questions but this wiring part is a whole new ball game for me. What do you guys think?

*edit* also running a RMVB th350 so i dont need any trans plugs either, and running a a1000 fuel pump so no fuel relays or wires eaither, only for the fuel gauge for my cluster

 

just remove everthing and wire in each circuit individually for the chassis.
for the engine:
if your running in open loop you can lose the 02 sensor wiring...
oil pressure you can lose...(cluster)
low oil level
maf
iacv
alternator wire. (cluster)
all smog.
knock sensors
what you need is, crank signal, cam signal, injector plugs, tps, map , coil packs wiring and coolant temp.

 

Why do I still need the water temp?

 

you probably dont absolutely 'need' it, but its always good to know the temp just in case something were to go wrong and cause overheating

i could be wrong tho. u may need it for fuction on something else also

 

Well obviously I need to keep a eye on the temp but I'm gonna run a autometer gauge for that but does the computer need it for refrence for anything else?

 

im not too sure. not sure if im imagining things, but i thought that i read up if the coolant sensor isnt plugged in, that the engine will not run right.....i dont remember exactly tho. hopefully someone will chime in on that to clear up that question

 

These guys can probably help you out.

http://howellefi.com/customer/home.php

Very nice OEM quality stuff.

 

you gotta have the coolant sensor for the pcm becasue it bases your fueling tables off of it,i did this to my car with a modifed 12 circuit painless chassis harness and then rewired the pcm as a standalone harness the best thing is have the factory manaul sit down and highlight all the uneeded emissions knock sensor,02's if your not using them like said above cam,crank,coill,injectors,iat,map,and coolant temp are needed along with the fuel level wire from the sender to pcm for everything on the cluster to work,also that serial wire goes to the obdII conn,along with a power and ground.,off the top off my head i think its purple,wire,you can also use the fuel pump trigger from the pcm to trigger a relay on for your a1000 it supplys a ground signal and is enough to signal it, .off the pcm there is a serial data line that will feed your cluster for the speedo,oil psi,fuel level water temp,i belive kurt urban sells a oil pressure port so u can use the stock oil psi sender and a mechanical gauge,also for the cluster you need a power,ground,and illumnation witch you can pick up right off the headlight switch for a short wire run,take the cluster out and use flat black paint on the cluster board to get rid of your abs,air bag service vehicle soon lights,the speedo is i think a green wire off the pcm down to the speed sensor the serial wire handles just about everthing in the cluster,i used just the stock alt wire for gen L on the pcm and alt.and a 8 gauge wire back to my shut off switch i layed out the engine harness on the motor and shortened and extended wires as i went for aclean look.lengthened the wires on the pcm to goinside the car along with my coils under the dash with the pcm wires coming out where the back of the intake is on the firewall make sure you keep both sets of injector power wires and also the grounds on the back of the heads,i was able to make a bracket where i cut out my fender aprons to mount the chassis harness and hide the wires for the headlites and fans in the core support if i think of any thing else ill let you ill try n get sm pics up theres almost no wires visible in my car hope this helps

 

holy crap spaulding, thats a lot of **** there that i couldnt follow, lol. Sounds like a lot more then i wanted to do. I wanted to ditch my cluster and replace it with all autometer gauges anyways so ill just do that. So now with that being said that will make it more of a engine harness and i wont need to run wires all over the place to run the cluster correct? The computer wont need any signal wires from my a1000 then right? I wont mind running the temp wire i guess but can i ditch the knock sensors in the valley cover?

 

I have a good friend that makes/modifies wiring harnesses for LS swaps and people like me that just want to get rid of all the unnecessary crap. He charges around from $3-500.00 depending on what you want done.

Let me know if you would be interested in having something like that done.

 

yea i would deff be interested just not right this second. Does he need a harness to mod or can he make me one from scrap? I found a guy on ebay who makes them from scrap for around $400. I just want bare minimum for plugs and wires so im tryin to find out here what i absolutely NEED. It will be ran in open loop SD so no o2's.

 

taubr unit post up pics when you get done...because ill be geting rid of all my wires to this summer when i install my stand alone and new motor

 

that is what i did with the harness in my firebird and it was actually pretty easy. only tookme a few hours one night. just use the pin-outs from the FAQ's in the conversion section. piece of cake. i kept my o2's and stuff but was still able to eliminate around 50 wires.

 

ya Phil, i tried that with my lt1 harness and it was HORROR! I have NO patience for that ****, lol. Id rather pay a few bucks for one already done and plug-n-play. Im getting tired of moddin stuff, just want the car done.

BTW i still have them 241 heads chillin here =)

 

i am sick as a dog right now. as soon as im feeling better i will give you a call and meet up with you to pick them up.

 

He can do it either way. I'll call him and ask what he would charge and get back with you.

 

cool, thanks alot!

 

I think im going to get a schematic of the harness and make my own. Im going to run it into the passenger compartment and extend the wires anyway. Im considering putting a weather tight connector in the engine campartment as well to make pulling the engine easier.

 

haha ya it is alot but if u break it down to indiviual sensors and wiring its not all that bad just gotta pay attention to where the factory put in splices for sum of the sensor for either 12 volts or 5volt ref.signals,the clusters not that many wires and if the pcm is in the car its only a few feet of wire that u can hide cleanly but if your goin the autometer route then u just have to worry about the inputs/outouts for the sensors goin to the engine if u look at the pinouts and do one at a time its cake,yes ull be able to ditch the maf,knock sensors,o2's,purge valve,vent solenoid,pressure sensor for the tank and be left with very little wires for the motor it may be easier to just by a universal fit conversion harness theres a few places out there that will taylor it to your needs and then u just have to supply power and ground to the pcm i just didnt wanna spend the money and have wired enough cars in the past to do it the hard way but then i was able to put everything where i wanted,i got mine set up so all my nitrous wiring is seperate from the chassis and the chassis is seperate from the pcm and to pull the motor i just unplug all the sensors slip the harness through the firewall and its all set to yank...good luck tho sounds like a cool project its just kinda hard to explain wiring over the internet lol

 

no need to extend the wires if you dont have heat or a/c. i ran mine right through the block off plate and had plenty of length to mount the computer in the glove box area.