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  • Bad Wiring Replacement Option

    I wrote this thread to serve as a potential light of hope and a starting point for anyone with wiring problems. It is NOT specific enough for a neophite to successfully accomplish. I was (many years ago) an electrical engineer and did electronic assemby work while in college, so I am very comfortable with wiring work. You must use good soldering and insulation techniques.

    Like many people I've had to deal with wiring insulation that was self destructing and making daily life with my car difficult....anything from performance "mood-swings" to CELs to no starts in wet weather. So I decided to bite the bullet and replace the entire engine harness assy.

    To begin I spent many hours searching through the forums here for ideas and got a good understanding of the costs involved. I was not keen on spending $1500 to $2500 for a new wiring set through Ford since my entire cost to buy my car and build it to date had been less than $2,500. I just knew that some cars that had done the wiring recall must be in junk yards and I just needed to find one.....NOT as easy as I thought! My 95 V6 w/MTX is fairly rare, and even after expanding my search nationwide for several weeks I found none in good condition.

    In the end I found a great and cheap solution that almost anyone who has a bit of patience and attention to detail can accomplish. I had found several 95 automatic cars in junkyards, most with good wiring. I knew that there would be differences but felt that this would probably be a surmountable problems since an Auto probably has more connections than the MTX.

    I was right, it worked, and cost me $30 from a U-Pull-it. Here's what I did (and I'm kicking myself for not taking photos):

    Pulled a nice clean engine harness assy from a 1995 V6 Automatic car.
    This included the wiring from the PCM to the square block connector by the intake and the "fuel charging" harness that runs over the top of the motor.
    I also removed the fan harness assy by cutting it just below and in front of the battery. My "Power Distribution" Harness is in good shape, so I skipped it.

    At home I removed my old wiring and layed out both harnesses for comparison, carefully checking each routing, color code etc. (this did require opening up much of the cable covering). I found to my delight that every wire out of the PCM connector for my MTX car was duplicated on the Auto Wiring. The Auto wiring had many extra connections. To make a long story short, I cut off all the unneccesarry wires and removed them from the assy by pulling them through. At the PCM connector NOTHING HAD TO BE ADDED - JUST DELETED.

    Here were the areas that took a few minutes of thinking and re-routing:

    4 of the wires that connected to the Automatic Transmission connector are retained and used for the MTX back-up light switch. They are the same colors as the MTX wires to the switch so you can solder on you old MTX switch without difficulty.

    A small red wire that runs from the square connector (by the intake) over to the alternator appears NOT to be on the Auto Wiring. However, a yellow wire comes from the same location and runs over to a dead end at the "Fuel Charging" Harness. You can re-route this and connect it to the red wire.

    Also a couple of wires on the Square connector go from one place on that connector to another place. These are different locations in 2 cases and just need re-routing.

    On the Fan Assy wire, I just cut my old off an replaced (soldered on) the new. ( and by the way, I found that although there are minor part differences, several other year harnesses work in this application)

    Other notes:

    Fuel Charging Assy is IDENTICAL between Auto and Manual.

    It took me 4 hours without any guideance or help. It worked like a charm with no CELs...I did this 4 months ago and no problems.....you can see my post on the Dyno forum that my motors making good power.
    95 SE
    2005 full 3L with COP
    Most commercially available hardware to go faster.

  • #2
    Good info. Thanks for posting.

    Comment


    • #3
      Wow - that was quite a project. My '95 Duratec ATX wiring was replaced under the recall (thankfully, the dealer didn't fight it) - but I spent some time checking over what they did. It's a pretty big job, and there are lots of places for it to go wrong.

      Congrats on a successful job!
      1995 Contour GL V6 ATX T/C
      1986 Mustang GT 5.0 (sold, but missed on sunny days)
      2000 Windstar LX

      Comment


      • #4
        Pin this one. Great information.
        Jim Johnson
        98 SVT
        03 Escape Limited
        10 Fusion Sport

        Comment


        • #5
          Very nice!!!
          Former owner of '98 SVT #1,173. Need a 95-00 Ford CD manual? PM me

          Comment


          • #6
            my story!

            I have a 96 mtx tour 2.5L.I replaced the upper & lower intake with a 98 svt
            intake.The wire harness fell apart in my hands while replacing the injectors.
            I could not find a good wire harness from a contour.I did find a 99 cougar
            with a very good harness.I installed it with cougar injectors because the harness was made for those injectors.The car runs like a champ!

            Comment


            • #7
              My daughter's 1995 DuraTec with MTX has the crumbling, flaking electrical wiring insulation decay affliction. Last few days here were rainy, after failure to start, I measured 500-800 milli ampere battery drain with everything off. Of course, this discharges the battery to the point of no start, in a short while.

              A call to Ford Motor Company Customer Service center revealed that the car has no recalls. The polite call taker did take contact information, and promised forward problem report to NTSA for consolidation in their data, which if enough of a pattern exists, could generate action by manufacturer. I will not hold my breath. I will hope that anyone else with the same malaise would report to Ford, at 866-436-7332, please see https://owner.ford.com/servlet/Conte...ge/RecallsPage Sure seems odd that such a prevalent seeming problem had no recall in effect. It was explained to me that recalls are specific to the VIN.

              Post author's description of "making daily life with my car difficult" is quite apt. I'm to point of either replacing or repairing harness. The original post seems to describe replacement of engine harness - author describes "the wiring from the PCM to the square block connector by the intake and the fuel charging harness".

              I've already reinsulated a few parts, with shrink tube, vinyl tape, butt splices, etc.

              The problem I noticed during reinsulating the short harness that runs from positive battery post to power distribution box (all exposed red insulation crumbled) is that alot of orange insulation on heavy conductors in the large harness (2" diameter) that dresses toward the cockpit/ignition switch is flaking/crumbling. So the problem on daughter's car is more widespread than engine harness.

              It also seems that when assembling the car, the wiring harness was installed before everything else.

              Nice thing is that I just found a factory service manual for reasonable price, it is on order. Is the PCM located at firewall on passenger side?

              Thanks!

              Comment


              • #8
                Originally posted by Slim57 View Post
                My daughter's 1995 DuraTec with MTX has the crumbling, flaking electrical wiring insulation decay affliction. Last few days here were rainy, after failure to start, I measured 500-800 milli ampere battery drain with everything off. Of course, this discharges the battery to the point of no start, in a short while.

                A call to Ford Motor Company Customer Service center revealed that the car has no recalls. The polite call taker did take contact information, and promised forward problem report to NTSA for consolidation in their data, which if enough of a pattern exists, could generate action by manufacturer. I will not hold my breath. I will hope that anyone else with the same malaise would report to Ford, at 866-436-7332, please see https://owner.ford.com/servlet/Conte...ge/RecallsPage Sure seems odd that such a prevalent seeming problem had no recall in effect. It was explained to me that recalls are specific to the VIN.

                Post author's description of "making daily life with my car difficult" is quite apt. I'm to point of either replacing or repairing harness. The original post seems to describe replacement of engine harness - author describes "the wiring from the PCM to the square block connector by the intake and the fuel charging harness".

                I've already reinsulated a few parts, with shrink tube, vinyl tape, butt splices, etc.

                The problem I noticed during reinsulating the short harness that runs from positive battery post to power distribution box (all exposed red insulation crumbled) is that alot of orange insulation on heavy conductors in the large harness (2" diameter) that dresses toward the cockpit/ignition switch is flaking/crumbling. So the problem on daughter's car is more widespread than engine harness.

                It also seems that when assembling the car, the wiring harness was installed before everything else.

                Nice thing is that I just found a factory service manual for reasonable price, it is on order. Is the PCM located at firewall on passenger side?

                Thanks!
                I have the same issue with my 1998 Contour SE. I was washing the engine compartment today and when I hosed everything down, I heard a sizzling sound coming from the battery/fusebox area. As I had my head down there listening to where it was coming from, smoke started coming up from under the battery area. Needless to say I double timed it to remove the negative battery connection. I pulled the battery but found nothing other than the afore mentioned flaking insulation on the two large red wires coming from the battery's positive terminal. I cleaned the area up (it was greasy and dirty as heck) and washed it down. After letting things dry a bit I reinstalled the battery and reconnected the cables. No sizzle sound or smoke this time. I'm a bit worried nonetheless.

                Has this happened to anyone else?

                I'm thinking about replacing that part of the wiring harness, but I'm sure Ford wants an arm and leg for it so might have to do a repair myself. Not sure if getting another harness from the wrecking yard is a good idea because it will be just as old as mine. Just for giggles, does anyone have a Ford part number for this harness?

                Comment


                • #9
                  You shouldn't have too much trouble with a 1998. I think Ford fixed wire defects in 1999, and AFAIK, 99 harness is not greatly different than 98. Cost of new harness is exorbitant, if available at all. You should be able to find decent used harnesses (there are three of concern) for a couple of hundred,for all three, maximum.

                  For my 1995, choices are much more limited. Odd thing is, when looking for engine harness for 1995 at pic n pull, I found a harness on 1995 Mystique that is not degraded, so either Mystique never had the insulation virus, or this car had undergone Ford corrective program. Most likely the latter.

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