Removing part of the engine wire harness

[9!'clipseDOHC]

I'm preparing for my turbo engine swap. I have the complete turbo engine wire harness and ECU and they are both out off the car. I have several plugs that I don't use on my NT so I figured before I do the swap I will remove all the plugs that I won't be using (bcs, egr, AC thermoswitch, ISC, etc).

My first question is, How do I do this? I understand that you follow the wires from the plug to wherever they start, I assume the ECU for the most part. But once I get to the ECU plugs, do I just pull the wires out of the ECU connectors? I've never done this before.

My second question is, If I remove the entire wires, all the way back to the plugs in the ECU, will it mess anything up?

I know this has been done before but I've searched and come up empty. Any help is very appreciated. Thanks!

 

[gsx7707]

i just replaced my engine harness.it was pretty easy.i did remove my dash it was a must for me to get to all the bolts to the heating duct.evrything will just unplug.i do know from my research that the n/t harness is different from the turbo.for the most part it isnt that bad. the good thing is all the plugs are different and will only plug to its mate.im pretty sure you will need a turbo ecu as well.goodluck

 

[half-cocked]

My suggestion is secure the unused plugs onto the body of the harness, theres no real reason other then aesthetics (and thats minor IMO) to totally remove the wire. But if your going to do it I dont see why there would be a problem, I have a 90 GST that doesnt use the EGR ac thermo etc.. but they are just unplugged. It would just mean that the ECU is seeing no value for them, mine runs fine like that, so the ECU would see the same if the wires were absent also.

 

[9!'clipseDOHC]

i just replaced my engine harness.it was pretty easy.i did remove my dash it was a must for me to get to all the bolts to the heating duct.evrything will just unplug.i do know from my research that the n/t harness is different from the turbo.for the most part it isnt that bad. the good thing is all the plugs are different and will only plug to its mate.im pretty sure you will need a turbo ecu as well.goodluck

Yeah I've done the swap before, about 5 years ago. Problem was I didn't have a logger or a tuner and I messed something up. At the time I was broke so I swapped my NT engine/ECU/harness back into the car (so technically I've done the swap twice). Now, I've got the time, money, experience and a lot more knowledge to do it the right way (I hope!).

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Here is my car dashless for the harness/ecu swap back in 2005. By the way, all the blue is gone. Back to black!

My suggestion is secure the unused plugs onto the body of the harness, theres no real reason other then aesthetics (and thats minor IMO) to totally remove the wire. But if your going to do it I dont see why there would be a problem, I have a 90 GST that doesnt use the EGR ac thermo etc.. but they are just unplugged. It would just mean that the ECU is seeing no value for them, mine runs fine like that, so the ECU would see the same if the wires were absent also.

Yeah mine are just unplugged as it is now and secured out of the way. Like you said I don't see why it wouldn't work, just want confirmation from someone who has done it. Since I'm not planning on ever having to use the plugs again, and I have easy access to the harness out of the car, I figure that now is the time to do it if ever. It would mainly be for aesthetics yes, but I really want a clean, simplified, engine bay.

Can anyone who has done this before post up with how it turned out?

 

[ramsack]

well a good reason to remove wiring for things not used is weight savings...

 

[kicker91laser]

Yes, you can completely remove the pin and associated wiring from the harness. When removing the pin(socket) from the ecu plugs, I always use a dental pick(paperclips work well too). You will want to pull the plastic dividers out of the plug, insert pick into the socket and this will release the socket and can be pulled out. Good luck, let us know how it turns out, there is alot of stuff that can be removed from the harness.

 

[9!'clipseDOHC]

Yes, you can completely remove the pin and associated wiring from the harness. When removing the pin(socket) from the ecu plugs, I always use a dental pick(paperclips work well too). You will want to pull the plastic dividers out of the plug, insert pick into the socket and this will release the socket and can be pulled out. Good luck, let us know how it turns out, there is alot of stuff that can be removed from the harness.

Awesome! Thats what I wanted to hear! Thanks! I will keep y'all updated on my project. I'll probably start a blog before I do the swap this summer so anyone interested can follow along.

 

[9!'clipseDOHC]

I started working on the wire harness tonight and I was wondering if there are any other plugs that can be removed? I'm already going to remove the EGR, AC thermoswitch, & BCS plugs for sure. I might keep the ISC plug, just in case I ever decide to reinstall it. Are there any other plugs that aren't needed?

 

[9!'clipseDOHC]

Update: I removed 3 A/C related plugs (A/C sightglass, A/C thermoswitch, and A/C compressor) all the way back to the ECU/Dash connectors. I also removed the EGR temp sensor plug. Until I can get some confirmation on the BCS for the 1g, it will stay. The wires are very easy to remove from the ECU connectors. You just pull out the lock and move the release with a small, precision flathead screwdriver and pull the wire out.

While I was removing the plugs I decided to re-route the wires. I didn't like the mess of wires that runs along the fuel rail and after looking at it, that route doesn't even make sense. The CAS, coolant and o2 sensors are all on the passenger's side of the engine bay, yet the wires loop around to the driver's side and back along the fuel rail to near where they started. I rerouted the above mentioned wires to follow the ICS plug. This allowed me remove a 2 feet chunk of the harness and get rid of the clutter along the fuel rail.

These pictures should help explain:

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The factory engine harness. Excuse the blue, it won't be back. This shows how the factory plugs are routed.

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This is how I rerouted the wires for the CAS, coolant, and o2 sensors.

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This is all that now runs along the fuel rail, all 4 injector plugs and the TPS plug. Thats it!

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What I have removed from the harness. 4 sensors, a 2' chunk of the harness, and lots of blue electrical tape.

 

[kicker91laser]

BCS wiring can be removed w/o any issues, dtc's.

 

[9!'clipseDOHC]

BCS wiring can be removed w/o any issues, dtc's.

Ok that's what I thought, when you install a MBC, you toss the BCS. I guess its different on a 2g and thats what I've been reading about lately. Thanks, thats one less plug and 2 less wires cluttering up my engine bay

I made a lot of progress today. Here is how it looks now, just about done.

 

[black_gst]

well hopefully you wont ever need to use those as inputs if you ever decied to run ecmlink

 

[9!'clipseDOHC]

well hopefully you wont ever need to use those as inputs if you ever decied to run ecmlink

I am planning on running dsmlink in the future but why would I need to use A/C, EGR, or BCS wires as inputs. I haven't looked into to dsmlink that much but I don't think what I deleted would be required. Will it?

 

[black_gst]

I am planning on running dsmlink in the future but why would I need to use A/C, EGR, or BCS wires as inputs. I haven't looked into to dsmlink that much but I don't think what I deleted would be required. Will it?

well the bcs and egr can be used to turn aftermarket things on like meth or nitrous kits on or as inputs for the ecu to read like wide band o2 sensors

if you decide you want to use those features you will just have to rewire pins back into the ecu

 

[GooeyGus]

Where did you get your harness?

My engine bay harness is just old and wires are beginning to crack. I'd like to replace it with a brand new harness, if they are available.

 

[9!'clipseDOHC]

Where did you get your harness?

My engine bay harness is just old and wires are beginning to crack. I'd like to replace it with a brand new harness, if they are available.

I pulled my harness out of a junkyard in Virginia about 5 years ago. I got the harness out of the same 91 laser that I got my ECU and 6 bolt 4G63t. I worked there at the time so I got to get what I wanted before it went out into the yard. I've replaced several plugs because of the same reason you are talking about but what I have now is in awesome shape. It looks brand new, even though its 19 years old.

 

[Jankenshank]

sub'd, i will be doing the same thing as you next week, im currently working on the body harness, deleting and clearing the;

AC/Hvac
Cruise
Remote Door locks
rear washer bottle and window motor
SRS

and anything else i can get rid of.

 

[9!'clipseDOHC]

sub'd, i will be doing the same thing as you next week, im currently working on the body harness, deleting and clearing the;

AC/Hvac
Cruise
Remote Door locks
rear washer bottle and window motor
SRS

and anything else i can get rid of.

Good luck on the body harness. When you get to the engine harness these links will come in handy. Color coded ECU pinouts and 1G ECU pinouts. If you have any questions about where any of the plugs go or anything else just let me know. Keep that reroute that I did in mind too, that's my favorite part of the new harness.

 

[92AWDHX40]

new harness are out there the dealer, got me one last week 100 bucks shipped ebay.

 

[Jankenshank]

having any luck?

 

[Jankenshank]

any luck??


just tucked mine and found it was really easy....

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[9!'clipseDOHC]

any luck??


just tucked mine and found it was really easy....

Your engine bay looks amazing! Great job. I didn't tuck mine, I just rerouted it. Here is the finished product. I kept my battery up front since I'm FWD.

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Here is the intake manifold, the only part of the harness up here is for the injectors and it's routed under the fuel rail. I kept my cruise control so thats the only clutter left.

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Here is the new route for the coolant sensors, TPS, and CAS. It's not invisible but it makes more sense instead of looping around the intake manifold.

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I also repositioned my coil pack, it was tight before with the Buschur/SX AFPR.

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I'm happy with how it turned out.

 

[Jankenshank]

i relocated my battery to behind the passenger seat,

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and ran a batt kill switch, and cut a 1" hole beneath the fuse box so i could run power wires through the fender instead of through the bay.

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ran the wires out of the old AC holes in the firewall whih i joined together and enlarged.

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then tucked everything behind the block

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sensors and injectors.

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