5.0 Swap Wiring Harness Mod Question

phutch11

Member
Nov 14, 2005
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For all you guys that have done the 5.0 efi conversion to your classic:

Does anyone know of a link, book, file, whatever that will accurately tell me what circuits I absolutely must leave in the late model 5.0 harness when I modify it for the swap?

Further, is there a source that will tell me how to tie in the existing (classic) engine bay harness so that I will still have functional oil, water and electrical guages (I know that the old amp meter won't work.)?

For those that have modified the 5.0 harness, was it worth the effort or should I just purchase a pre-made one?

Thanks
 
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do you have any wiring diagrams? if not i can send them your way via e-mail.

lots of info on this site http://www.fordfuelinjection.com/

about the only things you can eliminate are the tad, tab and canp. all the rest affects the way it runs. the efi harness has the oil and water wires in it and are color coded the same as your classic. everything else is basically an add on or tap into.

if you can solder its way more economical and neater to chop your factory harness, that is unless 10-15 hours of yours worth more than $400-$600, but i don't think people like that are going to work on their own car.
 
ashford,

I'd love whatever you've got in the way of diagrams. Right now my car is still at paint, but I'm trying to get as much done with the wiring in terms of research before the car gets back. Then I'll actually break out the soldering iron and get to work.

[email protected]

thanks a ton guys
 
roan65 said:

I used the Ford Motorsport manual pretty much exclusively when I did my EFI installation. I used a stock '92 harness and the Ford manual was very handy for identifying what's what. You'll find, by the way, that EEC-IV is pretty tolerant of missing stuff - evaporative emissions canister, air pump solenoids, even the vehicle speed sensor. It'll throw error codes when it notices they're missing, but won't turn on the check engine light, or dump you into hobble-home mode. Just about everything that connects directly to a sensor on the engine is critical (coolant temp, air charge temp, O2 sensors, etc), but most of the non-engine stuff isn't.

edit -- can't spell...
 
5.0 EFI Wiring Harness Info / Firewall Grommet

Hello, I'm right in the middle of finishing up my 5.0 HO EFI conversion on my '70 Mach1, and I'm doing the wire harness right now. I'm using the stock harness and modifying it. It has been confusing, but I think I've got a handle on it now after re-reading articles and diagrams a dozen times, and taking apart the stock harness to see where the wires actually go.

My question is where on the firewall in my '70 mach1 can a put a hole so I can get the harness grommet on and the wires on the inside?
I've searched but haven't seen anything for a '70. I don't want to just poke holes in the firewall to see where there is room...

The links below have been what I found and needed to figure this stuff out.

This link has been most useful, but still have to read it multiple times.

http://www.ford-trucks.com/article/...rive_Train_into_A_61_79_F100__F250_Truck.html

This link shows a NON-STOCK harness, so don't get confused, but it shows again the important connections.

http://fordfuelinjection.com/?p=6

Here is the stock harness info, that is useful, but doesn't show the actual connectors and layout.

http://www.veryuseful.com/mustang/tech/engine/

This link shows the actual harness and what wires go where, and was VERY useful to me, but again, you need more than just this link to understand things.

http://www.therangerstation.com/tech_library/Wiring_harnesses.htm

This was helpful a bit, and had some good links:

http://jr.stangnet.com/FiveOh.htm
 
jackmach1 said:
My question is where on the firewall in my '70 mach1 can a put a hole so I can get the harness grommet on and the wires on the inside?
I've searched but haven't seen anything for a '70. I don't want to just poke holes in the firewall to see where there is room...

remove the glovebox and take a look above the heater core. there should be a spot ~ 10 inches from the shock tower on the little slant below the cowl lip that you can drill a hole. all i did on my 67 was drill two holes (1 1/8" maybe??) with a hole saw, cut out the remaining material and then loose the heater core up a bit. that'll allow you to slip the connector through the firewall without too much difficulty.

if i remember to get pictures today, i'll post them in here tonight.
 
Bullitt, is this the spot where a wire from the fan motor goes into the firewall?

I fired up the motor today, fired up on the first try! Now I just need to tape up and wire loom the wires and run them inside the car. How do you fit the control box through the grommet hole??

Jack

p.s. just kidding about the box
 
When I did mine about 3 years ago I found the ford motorsport instructions to be the most useful. They pretty much tell you step by step what to do and include all the color codes. I used a '93 harness and computer...

68Restoman

519500_77_full.jpg
 
no problem, I moved the glovebox out of the way so I could get in there, and indeed the area where the heater fan wire goes there is clear right above it. Just big enough to get the stuff in there. Got the wiring all done taped up and installed and engine running. But somehow today when I started the car I got smoke from the drivers side and the left side parking lights are now on all the time. Everything else seems to work ok, but no sport lamps or horn, not sure they worked before though. This didn't happen before the stuff went inside the car, so I must have messed up some inside wires pushing the harness inside, it can't be electric issue, the engine harness only connects to the start+run from the original car. damn it. How does one get into the wiring behind the dash? Impossible from below really. If you remove the dash pad can you get to them from above?

Jack
 
How does one get into the wiring behind the dash? Impossible from below really. If you remove the dash pad can you get to them from above?

Not sure what year yours is, but my 65 has no more access with the dash pad off. It's all metal. (A real pain in the A$$ to install lining up trim screws)

The best access is by removing the gauge panel.