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I'm looking at building a custom wiring harness that jacks into the SMJ, takes over some pins that cuts out the ECU, and allows you to simply plug in the Link ECU into the SMJ and allow the Link to take complete control of the engine sensors and whatnot.

What my question is, and is probably more suited for vrg3 to answer...

On the intake manifold side of the harness (F25-F27) the F27 connector plugs into E3 and all of it's connections are grounded on the manifold.

Are these of any significant importance? some are wired directly to the ECU. D15 on the ECU side taps into connector F45.11 which goes to Pin 3 on the Ignitor, is it important to keep these groundings seperate or not?

AT F27/E3 there are two ground points, one for pins 6,5,3,4 and one for pins 7,8,2,1.

are these seperate for any perticular reason?


Is Yellow/Yellow Red/Yellow Red with stripes a common 12V source wire?


On connector F25/E1 - the ground (trigger) points for the four injectors are pins 9-12; they plug into pins D13,12,11,26 on the ECU with colors Br,Lg,LW,L (same order). do these go to the SMJ? In other words, can you disconnect them at the SMJ and splice into them?


Is it OK to assume the wire color that you have from one device (such as an injector) is the same all the way back to the ECU? Do the colors typically change over at the SMJ? (I know Ford has a BAD habbit about this, and it makes wiring HELL)


what do you think will be easier, building an adapter for the current ECU so that you can just plug in the Link in the stock location, or wiring in at the SMJ?


comments, opinions, feedback and things of that nature.

The price on the Link is ~$1200 depending on how long of a loom you want, that's the Link 1 (wideband support) the Link 2 is ~$1700 (again depends on the length of loom)

I would say it makes a lot more sense to do it at the ECU. As you say, not all the signals go through the SMJ (in particular, none of the signals that have shields do if I recall correctly). And a lot of non-ECU stuff goes through the SMJ, no?

Colors do sometimes change. Just use the FSM wiring diagram to follow them. In fact, several of your questions can be answered by looking at the wiring diagrams.

I don't know exactly why the grounds are separated... Part of it is just to avoid running too much current through one ground. In general, I'd suggest trying not to change too much from the factory setup.

Allright, thanks - it started clicking together last night once I printed off your ECU pinout diagram.


I'm looking at scans of the FSM, I've got some yellow combination wires that go to other pages (which I can't find)

such as page 25 of the electrical engine wiring, the Ignitor has pins 1 (YL) and pin 4 (Y) going to a different page - I can't figure out if these go directly to the ECU somewhere on another page or if they go to their own seperate fuses and then to an ignition relay or what.


In short, I'm unable to follow some of the numbers and letting on the FSM scans.

Wires that go to the top/side/bottom of the page to a little box numbered [1] or [2] - no clue where that's at.

And wires which point off to the side to a circled letter such as C or F.

Ignitor pin 1 (yellow/blue wire) goes into the SMJ (connector B27/F45) and ends up at ECU pin F47.10 (Cylinder 1/2 ignition). Trace the wire and you should see it.

The circles tell you to follow to a different page. For example, follow the "F" on page 25 to the other "F" on page 22, and you'll find that ignitor pin 4 (yellow wire) goes to the fuse box, to the EGI fuse, number 16. This fuse also powers the ignition relay and feeds the ECU's ignition swtich signal (pin B48.12).

The numbered boxes connect between left-facing and right-facing pages.

You should be able to figure these things out, but it will take some time to familiarize yourself with the diagram. Print out these pages and lay them out as they would be in the book; that might make it easier to see.

Defintaly do it at the ECU connectors. Not only is it easier, and quicker to access, but you can use the space where the old ECU was to mount the Link. Plus there are patch harnesses that fit if you get lazy and dont feel like disassembling an ECU for the connectors.