ISO guidance for wiring and reprogram ('54 Customline onto '99 Grand Marquis frame)

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  1. #1

    Default ISO guidance for wiring and reprogram ('54 Customline onto '99 Grand Marquis frame)

    I have a '54 Ford Customline with antiquated frame, suspension and driveline. It also has a rusted out floor that will get rebuilt as is convenient.

    I also have a lower-miles '99 Mercury Grand Marquis that was recently hit in the side. After insurance is over, the car may be totaled (the cost fo two doors and paint probably is close to KBB), or I may just take the cash and call it on the '99 anyway.

    I am looking at what will be involved at putting the '54 body one the '99 chassis. I have the skills to do the metal work (assuming the front W-W isn't too wide?) to mod frame and body to fit. My concern is how much of the wiring I may need to keep?

    Where can I find guides to weeding out ("dieting"?) the harness to minimum? I want only what is necessary to make the engine/trans combo run like it does now, and possibly the CEL. I'd be fine with losing the ABS too.

    Also, are there good sources for reprogramming the PCM? Or should I look for a somewhat local shop in case I need changes?

    Finally, with a decent flowing filter/intake and a decent flowing exhaust, what performance gains can be expected from a otherwise-stock '99 4.6 with a reprogram and still run reliably?

    Thanks for any insight and wisdom, and I appreciate any correction of my direction here.

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  3. #2
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    May 2018


    Hi there,
    this is an interesting project.

    my first question is how do you ultimately want Your 54 customline to look? personally i like the totally stock appearance especially interior and dashboard.

    Ie stock steering column or use the Marquis steering column?...also i believe that while the total track of the the Marquis may be similar but it is achieved in a different way, these more modern vehicles have very flat faced wheels from factory so if u plan to use them ok but in my opinion they would detract from the Customlines style, older style wheels would require spacers to make them fit over the brakes so now things are getting too wide.

    Im building a 56 F100 and using a 99 Expedition as an organ donor... in the beginning i was considering the drop on approach but that soon changed, so now i have built my own airbaged chassis and cut down the 8.8 rear end to narrow it sufficiently, will also use engine and trans and not much else.

    As for the wiring we come back to some aesthetic points, do you really want plastic fuse box etc under the hood? personally i think that harvesting anything more that the ECM, PATS and connectors will be a waste of time...what you need is the ECM and connector and if you wish the actual engine wiring ie ignition,injectors,AC, various senders...i think the chassis wiring could be more easily taken care of with a basic $200 hotrod wiring kit.

    There is plenty that can be done to the 2 valve engine to wake them up, personally i don't have any knowledge on re programming sure the mustang guys can help.

    my ten cents regards Jonathan

  4. #3


    I'm doing something similar. I'm putting a 4.6 in a 56 Customline. However I just went with a mustang II front suspension and an 8.8 from an Explorer. Ron Francis wiring does a re-flash on the computer. Not sure what the price is yet.

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  6. #4
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    Mar 2014
    Spotysylvania VA


    Unless your frame is rusted out, it's not bad, it's a box frame, chevy's had C channel which is weak. I put a 5.4 DOHC in my 54 Customline Coupe, added a Fatman front frame section and put a custom Currie 9" 3:70 gear, drag race, no problem after 40,000 miles

    - - - Updated - - -

    About the wiring , go on Ebay and look up EVTM (wiring diagrams) for the year make and model your working with. It takes some time but you can use it to delete what you don't want

  7. #5


    Like Falconstein suggested eBay may be able to provide you the manual (in used but good condition) if you search on '2003 Ford Mustang EVTM' in their Auto Parts and Accessories listings. You can frequently (but not always) find the manual you are looking for over there at a significant discount off the Helms new book pricing.

    If none are available you can always Google Helms Publications who print and distribute the books for Ford. I bought mine from Helms in 2005 and I think I paid something like $60 or so. Brain fade, I can't remember exactly what I paid anymore but that is a good ballpark number from Helms, so the eBay alternative can save you considerably. In the FWIW bucket, the book really is indispensable when you are involved in a project like you are.

    The manual is also included in the digital version of the 2003 Ford Mustang Cobra Repair Manual which you can download from the ModFord's Terminator Table of Contents (TToC) in the 2003 - 2004 SVT Mustang Cobra forum. The digital version has the benefit of being able to save pages from the manual in PDF format so you can print them out for use at the vehicle as you are working on it. Because you can always reprint a new copy of the page you are using, it doesn't matter if you get them oily or wet etc.


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