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Wiring Advice Sought... 911 Engine Harness


Mike D'Silva
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So... I'm at the stage of starting to get a wiring harness ready for the 3.0 engine I am reassembling.

The harness that came with the engine is a bit grubby but I think is still serviceable.. However, the multi pin connector that normally plugs into the rear of the car, has been removed for some reason. Here is a photo of what I have with the harness. Can I simply buy another plug and put it all back together?  Does anyone have another plug?

Also, since I intend to go efi, what do I do with all the extra connectors and plugs? Leave them hanging and tape them up? or undo the tape and trace them back and remove from the harness?

RA8Fi1B.jpg

 

 

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well, since I`ve been there a while ago and had quite a problem with identification I can say this much:

some of those wires you gonna use in efi setup. ECU power, coils and injectors are the essentials. some of those are sensors to gauges wires which you might need if you want the original gauges to work (oil temp, oil pressure, oil level). there are 1 tacho signal wire which is quite useful to say at least. 1 rear gear light etc. And you will have some of them useless. If the car doesn`t have an engine and it`s easy to get rid of the useless once - loose them. If not - tape them and leave for now. 

The biggest problem for me was to identify all of them. Seems quite easy considering forums and manuals but either I`m lucky or my car was pretty confused at the factory or later in someones hands none of the pin outs fitted my colours\numbers. So I just made my own pin out.

Btw, there could be another one like that (for the U.S. market cars though) to control emissions. 

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Mike,

You can buy the plastic connector housings quite cheaply.  The part number is shown in the PET.

Since you are converting a CIS car there won't be too many circuits you won't be using so I'd just remove the (other) end connectors and tape the loose wire to the harness.  That way if you return to CIS, it's easy to reinstate the harness.

For the EFI you would create another separate harness to run the injectors, COP's, AIT, MAP, TPS, head temp, crank and cam position sensors that plugs directly into your ECU. 

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Thanks Peter. I just ordered the plug today (hope I got the right one; female part)... And the rest of the harness is provided by Rasant.. and looks kinda like this VmHNtPE.png

4 hours ago, Cheshire Cat said:

well, since I`ve been there a while ago and had quite a problem with identification I can say this much:

some of those wires you gonna use in efi setup. ECU power, coils and injectors are the essentials. some of those are sensors to gauges wires which you might need if you want the original gauges to work (oil temp, oil pressure, oil level). there are 1 tacho signal wire which is quite useful to say at least. 1 rear gear light etc. And you will have some of them useless. If the car doesn`t have an engine and it`s easy to get rid of the useless once - loose them. If not - tape them and leave for now. 

The biggest problem for me was to identify all of them. Seems quite easy considering forums and manuals but either I`m lucky or my car was pretty confused at the factory or later in someones hands none of the pin outs fitted my colours\numbers. So I just made my own pin out.

Btw, there could be another one like that (for the U.S. market cars though) to control emissions. 

Thanks for the reply. I 'think" I have a bit of an idea today.. I downloaded a couple of SC wiring diagrams that show the wire colours and what they are for. For things that I no longer need such as warm up regulator and thermotime switch, I will likely just tape them up and put to one side. I don't want to butcher this harness any more than has already been done.

The AEM ecu has cables for starter, key on, fuel pump, tach etc, so I need to somehow tap those in. I'm just not 100% sure where but once engine is in, will hopefully have more of an idea. The fun part is, I am colour blind.. 

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I know you like to do things properly.  I'd peg the harness up on a board like the pros do and unwrap the old tape, identify what you need from the diagrams, remove, replace where necessary and rewrap.  Depending on provenance you might have non-standard wires in there.  Nobody is going to return your Efi to cis, ever, so might as well do it properly.   Proper function requires good connections and once it goes in the car impossible to fix and could lead to days of troubleshooting.

Your project so your call but if it was me I'd be all in on fresh connectors, fresh tape and checking all wires and discarding unneeded.

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1 hour ago, Coastr said:

I know you like to do things properly.  I'd peg the harness up on a board like the pros do and unwrap the old tape, identify what you need from the diagrams, remove, replace where necessary and rewrap.  Depending on provenance you might have non-standard wires in there.  Nobody is going to return your Efi to cis, ever, so might as well do it properly.   Proper function requires good connections and once it goes in the car impossible to fix and could lead to days of troubleshooting.

Your project so your call but if it was me I'd be all in on fresh connectors, fresh tape and checking all wires and discarding unneeded.

Thanks Bruce.

I'm contemplating having a custom new harness created, but from what I can tell, that is approx $400-$500 usd.. And since I need very few connectors, it just seems kinda steep. I don't want to hack up the original harness; that kinda goes against my desires to keep things original "just in case" it does go back to CIS.

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19 minutes ago, Coastr said:

How hard can it be to make a new harness?  Surely there’s a YouTube vid on that somewhere??

Wire, connectors, tape, crimping tool, measuring tape, job done!

if it’s only $400 or so for a new one that means it not that hard to make, right?

Agree, but I have to draw the line somewhere... 

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I am going to go through the same thing soon, and my plan is to keep the original harness in there, mainly for the lights, etc, and run a new harness for the ECU. Even though my car is far less likely to ever be put back to CIS, I do like to leave standard where I can (although a lot of it is more I am too lazy to strip out all of the unused stuff).

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Having a bit more of a think, there is really not much to it. I don't think I need ANY of the special connectors.. all I need to connect up are starter, alternator, oil temp, oil pressure sender and oil pressure warning switch.. these all use ring terminals or some sort of spade connector. But I have little to no knowledge of auto wiring so I have no idea what wire to use or where to get it. The 14 pin connector I got from Porsche is the only part that I think needs to interface with the car. And really, it is just there to feed info back to the gauges I think...

 

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This place seems OK.. you can order some with stripes but I am not sure the difference between general purpose or heavy duty.

http://www.rapidcables.com.au/general-purpose-automotive-cable

 

I might order some, and will have tonnes left over. for another engine harness or two.

So Rapid Cables has LOTS of stuff. 

 

 

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Mike,

I recall the Porsche produced wiring diagrams have the nominal (conductive cross sectional) area listed on each circuit.  That should be an easy way to get the info you need to choose the right size.

 

Good find BTW!

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Just thinking a good source of wires would be at the wreckers. As you really want a heap of different colours, buying every colour in 10m rolls would end up with a lot of excess. Could be worth considering for some considering doing this.

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As im sure you guys  know old “original” wiring is crap no matter how good you think it is the bad connection always let’s the rest down, personally I would just get one of these and be done with it. Nothing worse than having a nice newly finished project with electrical gremlins. 

http://www.ultimateproducts.com.au/index wire kit.htm

Or this guy, he list Porsche but I can’t see a model. Some cotton braiding would look a treat under any dash or hood. 

https://www.vinwire.com.au/vehiclelist.htm

 

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On 4/20/2018 at 4:27 PM, Peter M said:

Mike,

Might be worth getting a price off timmy2 from Pelican Forum.  He does Al's harnesses and is well regarded.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/812816-engine-harness-multi-pin-connector-carb-conversion-83-sc.html

Timmy2 (Denis) has been helping me a lot via email. His harnesses are not "cheap", and now I can totally see why. 

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On 22/04/2018 at 7:06 PM, MFX said:

Just thinking a good source of wires would be at the wreckers. As you really want a heap of different colours, buying every colour in 10m rolls would end up with a lot of excess. Could be worth considering for some considering doing this.

Start doing it before we hit the Copper Shortage. 

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