DIY Harness

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HardVG

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Just looking at harness options, I already have the factroy engine harness and I am wondering who has used this rather than buy a complete new aftermarket harness. What is required to make it work. It would be nice if somebody produced an add on harness, which could be run in parallel to the factory one to cover the additional circuits required. Something like this would really drop the price on getting the motor up and running.
 
If you can get a wiring diagram that is accurate, there is no reason you could not re--work the factory harness.

SOMEBODY knows this stuff because you can buy it. I simply don't have access to the factory docs, and I'd guess that from the first year to present, there's been a few changes.
 
Those factory wiring diagrams are not the easiest to follow. I'm just thinking that if you already have the factory engine harness, you probably have 75% of what is needed. I know the aftermarket harnesses are nicely done and all, but it would be nice to be able to put that $950 or at least part of it into something else. If you could buy a simple add on harness for somewhere south of $500 it would be a great thing.
 
IMO the EFIsource.com mega squirt is the way to go...1 hot,2 grounds, keyed 12. it started. price is very reasonable
 
HardVG said:
Those factory wiring diagrams are not the easiest to follow. I.
Click to expand...

I know. But I tend to treat these "as a black box."

If you have "a box" containing the ECU, the harness, and all the harness connectors that go to all the sensors, there are only so many "unknown" conductors. I'd agree if you think some of them could "trip you up." But you eliminate the ones you know, you research the ones you don't, and pretty soon you are down to a few unknown connections.

One big problem that seems to plague these, without "commercial help" are the security system that's (I'm told) interconnected with the column.
 
HardVG,

I have not, repeat I HAVE NOT tried to modify a factory harness to work. I KNOW it has been done though.

Here are my suggestions if you are inclined to give it a try.

1. Pull the motor and harness yourself.
2. Get as much of the harness as humanly possible, besides the engine harness there is a harness that connects the drive by wire throttle and the dash gauges to the engine computer. So getting the as much of the dash harness as possible is probably a good idea. Also the diagnositic port is located under the dash so you will need it to diagnose any computer issues.
3. Choose a post 2003 motor that uses a single ECM for both transmission and engine management
4. Choose a pre 2006 motor that doesn't use a SKIM key.
Basically a SKIM key embeds an RFID in the key so that a handshake occurs between the key and the computer, no handshake = no start.
5. Get a copy of the correct FACTORY SERVICE MANUAL. They are floating around the interwebs, they have copies on ebay for about $8.00
6. Print out the pages that deal with the wiring harness. Printing at home on a ink jet printer costs about 20 cents per page, so it might be cheaper to go to kinkos and print there at 5/10 cents per page.
7. If you are NOT going to run a factory transmission you can delete the transmission wires along with a number of other wires.
8. Find someone with a factory scan tool. When places like Hot-wire talk about "reprogramming" the computer what they do is use the factory scan tool to disable a number of features that you won't be using. For example if you are running a 727 or 904 transmission, they simply tell the computer that you are running a manual transmission.

This should get you pointed in the correct direction.

Good Luck,

You'll probably need it. ;)

Regards,

Joe Dokes
 
I had a 2008 SRT8 donor car so I already have the complete engine harness and ECM, I did sell the body though and the rest of the wiring wnet with it. I don't know if the ECM can be used, might be a bit too modern, but the engine harness bascially runs back to these two plugs plus a heavy lead to the battery, the orange plug connects straight to the ECM:



So realistically, there is no need to touch the actual engine harness at all except for the benefit of tidying up the wiring a bit, which you can do yourself with a couple of rolls of electrical tape. You already have connections to all of the engine sensors, injectors, ignition coils and such like. What you really need is just the connections to the rest of the car.
 
One guy said he did. Never divulged any info though.

Come on, it can't be that hard. :)
 
I have started on mine but as usual life is getting in the way. I have it paired down to only the wires I believe I will need. Biggest thing that got to me other than the hours and hours of time going through the diagrams was shelling out the $60 for the special
Little tool that was needed to remove the wires I don't need from the connectors. I still have t decided if I want to she'll out the money for the skim ring a d a programmed key to see if it will work like I believe it will or just have the Ecu reprogrammed
 
I thought I would email Hotwire Auto to see if they would make up something, but no, so looks like DIY is the only option.

I managed to get the pins out of my plugs with a homemade tool. I followed the non-engine wires from the ECM to wherever they went and pulled the pins at that end. Have to have another look and see what I actually have now. I know I will need the OBDII connector for the predator because I haven't got that.
 
HardVG said:
I thought I would email Hotwire Auto to see if they would make up something, but no, so looks like DIY is the only option.

I managed to get the pins out of my plugs with a homemade tool. I followed the non-engine wires from the ECM to wherever they went and pulled the pins at that end. Have to have another look and see what I actually have now. I know I will need the OBDII connector for the predator because I haven't got that.
Click to expand...

making any head way?
 
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