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Shortening the main harness

 
Old 06-21-2019, 12:52 AM
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Default Shortening the main harness

I have a 97 harness that connects the ECU behind the passenger seat. I was thinking that with gutted doors and lack of windows, any water (rain) while towing on an open trailer may lead to moisture /water getting to the harness and MS3 box if behind the passenger seat. I thought that the NA6 location in the passenger footwell under the dash may be a safer location for the MS3 box. Being OCD, I started thinking that the additional 2ft of harness may not be needed and may be need to be tucked away somewhere under the dash curled up if using the Singular NA6 bracket and studs already built into the chassis in the footwell.

I don't really see a need to keep the extra 2 feet of harness wire and perhaps shorter harness may be more beneficial and also lose a LBS or 2.

The question here is to:

1. Avoid splicing - do nothing and just tuck it away
2. Cut the harness and splice each wire with butt connectors
3. Mil Spec connectors
4. De-pin each wire, find new pins to purchase and cut the harness and reinstall pins and OEM connectors.
5. See a shrink

What would you do?
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Old 06-21-2019, 01:24 AM
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Originally Posted by stevos555 View Post
I have a 97 harness that connects the ECU behind the passenger seat. I was thinking that with gutted doors and lack of windows, any water (rain) while towing on an open trailer may lead to moisture /water getting to the harness and MS3 box if behind the passenger seat. I thought that the NA6 location in the passenger footwell under the dash may be a safer location for the MS3 box. Being OCD, I started thinking that the additional 2ft of harness may not be needed and may be need to be tucked away somewhere under the dash curled up if using the Singular NA6 bracket and studs already built into the chassis in the footwell.

I don't really see a need to keep the extra 2 feet of harness wire and perhaps shorter harness may be more beneficial and also lose a LBS or 2.

The question here is to:

1. Avoid splicing - do nothing and just tuck it away
2. Cut the harness and splice each wire with butt connectors
3. Mil Spec connectors
4. De-pin each wire, find new pins to purchase and cut the harness and reinstall pins and OEM connectors.
5. See a shrink

What would you do?
From best to worst
5. You sunk a ton of money in a $2000 car
4. The right way
1. Easy and will work
3. kinda a pita and not necessary
2. I wouldnt
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Old 06-21-2019, 03:08 AM
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If you want I've got a spare ECU plug pre-pinned with about 6ft of wire.
Came with an old ECU I had, and yeah, I never needed the loom.

Not this one, but same idea, plug on one end, bare wire at the other.




PM if you want details, pics of actual thing, etc etc (also to check the plug on the USDM is the same as AUDM)
Bear in mind, i'm in Australia, so take into account postage costs/time if you're in a rush.
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Old 06-21-2019, 03:47 AM
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Any additional cuts/joins/connections you add are going to be an additional point of failure that will probably bite you at some point in the future...

I'd neatly tuck the cable away somewhere behind the dash. Another ECU mounting option might be to put it behind the glovebox - I made a bracket which goes from the bottom glovebox support (where the hinge is) up to one of the studs on the back of the firewall, which is even further away from the weather.
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Old 06-21-2019, 09:02 AM
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You can get the pins on Digikey or Mouser. There are two different sizes. Depinning and repinning the connector is easy, but crimping the pins on is hard without the right tool.
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Old 06-21-2019, 09:18 AM
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which tool would be appropriate to use ? Do you have links to the part on Mouser ?
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Old 06-21-2019, 09:41 AM
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My gut is to suggest not doing anything and just re-bundling it with some zigzag folds and tuck it away.

Reasons:
1. very hard to **** up
2. anything that unwires an ecu harness is very easy to **** up
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Old 06-21-2019, 09:44 AM
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That's likely what I am going to end up doing and trying to hang this under the crash bar.
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Old 06-21-2019, 10:28 AM
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I wanted to do the same thing in my 97, but too many opportunities to introduce failures.


it RE-pin, or leave it alone completely
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Old 06-21-2019, 11:34 AM
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Originally Posted by y8s View Post
My gut is to suggest not doing anything and just re-bundling it with some zigzag folds and tuck it away.

Reasons:
1. very hard to **** up
2. anything that unwires an ecu harness is very easy to **** up

This is the correct answer. The chances of ******* **** up is high, and not worth introducing more faults into the wiring.

I started doing shortening my harness in 2007. Over the years I have made tons of changes in it by cutting and splicing. It is now 2019 and I am completely redoing the harness in my car. I am over $1000 in parts and tools to build a new harness. I am over 100 man hours into the job. It had turned out to be far more of a pita then you would ever think.
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Old 06-21-2019, 11:43 AM
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Just like me. starting a project which turns out to be 5x more in cost and time.
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Old 06-24-2019, 09:08 AM
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Originally Posted by stevos555 View Post
which tool would be appropriate to use ? Do you have links to the part on Mouser ?
I do not have the part numbers handy. I found them on MT.net somewhere.

The correct tool is not the needle nose pliars and solder we used on my friend's car or my car. But we were only adding a few wires for things like boost control and sequentail fuel, not redoing the whole thing.
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