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1991 Grand Marquis Engine Harness

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    1991 Grand Marquis Engine Harness

    Hey, looking to finally fix the butchered engine control wiring in the '82 Mark VI, and was wondering if a 1990 Lincoln Town Car harness would work for that.

    I will have my dad call around tomorrow to a bunch of salvage yards that actually list the parts in wiring/electrical to get a complete engine harness. Basically need everything from the computer plug at the firewall out to all the engine sensors and such, and up to and including the EECIV test plug.

    The car has been having some trouble starting recently, and it's acted up before, so I finally made an appointment to get it taken care of near the end of the week. When I was at ScottFest two years ago John tore into the harness and couldn't figure anything out on why it was running rich and we found a wire that was not connected from the transmission (hooked it up and it didn't do diddly), and in a recent thread on here it was mentioned that the transmission sensor wire not being hooked up properly can make it run pig rich and or cause the EGR to open at completely stupid times.

    I'm looking to get said part ASAP, but local you-yank-it places no longer stock cars that old ('91 GM).

    I was going have my dad order it tomorrow or the next day, especially if the salvage yard is willing to toss it in the mail Priority 2-3 day so I can get it in time to send it with the car for the appointment on Thursday.

    But if anyone here has access to grab me one or could get one at a local yard and get it out in the mail by Tuesday I could use a PM. (or knows if the '90 Town Car harness is basically the same except needing to do the mass air wiring changes, that would be a big help) I might be able to rob that part for free, but the other harnesses are listed between $75-125.
    ,
    Slicktop '91 GS HO 4.30 rear. '82 Mark VI Tudor HO, '90 F-150 XLT, '62 project Heep, '89 Arizona Waggin' and '88 donor in PA, getting combined.

    #2
    Considering it's an HO swap... running an A9M (A9P-ish)... I don't see why not. Sorting that clusterF! of relays by the booster would be nice too. Just remember that the autolamp relay is SOLDERED to the metal clip it's mounted to and is made quite much of unobtanium. Conversion to the 92-94? 6-pin relay is the only way if that thing goes out.

    You would have to sort the MAF wiring though. Transfer that to the new harness.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

    Comment


      #3
      Gonna have to search on here for MAF conversion wiring diagrams to helpfully copy for the shop, I guess. It's ordered.
      ,
      Slicktop '91 GS HO 4.30 rear. '82 Mark VI Tudor HO, '90 F-150 XLT, '62 project Heep, '89 Arizona Waggin' and '88 donor in PA, getting combined.

      Comment


        #4
        Don't quote me on this, but the 90 towncar ecu harness is wired differently I think. Also 90 tc is not mass air

        Comment


          #5
          If it's just the engine/trans harness... it should be close enough with the hack job that is under that hood. I did my best to replace the vampire taps and butt crimps with soldered joints, but it's still a mess.

          Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
          rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
          Originally posted by gadget73
          ... and it should all work like magic and unicorns and stuff.
          Originally posted by dmccaig
          Overhead, some poor bastards are flying in airplanes.

          Comment


            #6
            Well, looks like the electrical guy noped the F out, doesn't want to tackle the job, so I have him checking out the battery, alt, grounds, and starting/charging system to see if anything is weak. I had already replaced the positive and negative (to engine block) battery wires, and I tossed the other wire I bought (that goes down to the starter?) in case that one is crusty.

            I guess I might have to tackle this job myself, at least I have both EVTM books for the '82 Mark VI & 91 Grand Marquis. The water looked low in one of the 6 holes, actually if it's supposed to be up to line I sorta see at the 3/4 or so level they all looked low with one super low one.

            Maybe I can tackle it during my vacation week in June. I dunno.
            Last edited by sxcpotatoes; 05-08-2019, 06:40 PM.
            ,
            Slicktop '91 GS HO 4.30 rear. '82 Mark VI Tudor HO, '90 F-150 XLT, '62 project Heep, '89 Arizona Waggin' and '88 donor in PA, getting combined.

            Comment


              #7
              Also really awesome/helpful: I have that '91 in the driveway that I can look at/compare for wiring routing, etc.
              ,
              Slicktop '91 GS HO 4.30 rear. '82 Mark VI Tudor HO, '90 F-150 XLT, '62 project Heep, '89 Arizona Waggin' and '88 donor in PA, getting combined.

              Comment


                #8
                Get a harness from a '90 california town car or '90-'91 CV or GMQ, they have all the maf shit. Plug into A9 computer and done!

                Wish i'd had the time, patience, and foresight to gut my wrecked '90 of all this type of shit.

                Comment


                  #9
                  Its honestly not hard to re-pin an SD harness into mass air. I expect moving a few wires is easier than finding a Cali MAF harness.

                  The slightly more difficult part will be figuring out what on the harness needs to connect to what on the body. Mercifully there isn't a ton of interaction, but you do have to connect the key-on power, fuel pump wiring, start circuit, and VSS stuff.
                  86 Lincoln Town Car (Galactica).
                  5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                  91 Lincoln Mark VII LSC grandpa spec white and cranberry

                  1984 Lincoln Continental TurboDiesel - rolls coal

                  Originally posted by phayzer5
                  I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                  Comment


                    #10
                    Originally posted by gadget73 View Post
                    Its honestly not hard to re-pin an SD harness into mass air. I expect moving a few wires is easier than finding a Cali MAF harness.

                    The slightly more difficult part will be figuring out what on the harness needs to connect to what on the body. Mercifully there isn't a ton of interaction, but you do have to connect the key-on power, fuel pump wiring, start circuit, and VSS stuff.
                    Yeah... and that HO swap was a real redneck job. It was very unreliable when I got it. The only real issue it had left when Nick got it from me was the weird idle and rear axle (that he mentioned later on), but at least it didn't die while stopped in gear with the AC on any more.

                    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                    Originally posted by gadget73
                    ... and it should all work like magic and unicorns and stuff.
                    Originally posted by dmccaig
                    Overhead, some poor bastards are flying in airplanes.

                    Comment


                      #11
                      yeah any previous hackery will add to the irritation. If it was all stock at least the manuals would indicate what is where, once people have gotten their dirty dickbeaters on it, all bets are off. My own cars are not immune from this. I feel for anyone who tries to figure out my Towncar.
                      86 Lincoln Town Car (Galactica).
                      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                      91 Lincoln Mark VII LSC grandpa spec white and cranberry

                      1984 Lincoln Continental TurboDiesel - rolls coal

                      Originally posted by phayzer5
                      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                      Comment


                        #12
                        This is one of the main reasons that my 93 may just become the "racecar" or backup car and I may start driving the Expedition most of the time. No mechanic wants to dick with that car. And young ones always give me shit about the wiring in it being a fire hazard (older ones notice everything is fused and just avoid touching any of it if they can help it). I seriously doubt anyone would ever want to buy that car off of me no matter how good it runs now. And I really wouldn't want to inflict it on them anyhow. There are literally 3... maybe 4 people (including me) that might understand it all and be able to work on it, but I know at least 2 of them have told me they would never work on it again and the other guy probably wouldn't want to take it on.

                        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                        Originally posted by gadget73
                        ... and it should all work like magic and unicorns and stuff.
                        Originally posted by dmccaig
                        Overhead, some poor bastards are flying in airplanes.

                        Comment


                          #13
                          Looks like the alternator/charge cable was loose. Maybe that was undercharging the battery or causing starting problems?

                          How full of water are the battery holes supposed to be under those caps 1/2? 3/4?

                          Crossing fingers it starts for work in the morning. My dad took it a couple places the past couple days and it started for him every time. Best part was, no charge for checking it out/tightening the cable.
                          ,
                          Slicktop '91 GS HO 4.30 rear. '82 Mark VI Tudor HO, '90 F-150 XLT, '62 project Heep, '89 Arizona Waggin' and '88 donor in PA, getting combined.

                          Comment


                            #14
                            about 1/2-3/4 sounds right. Most batteries are "sealed" but under the caps you'll usually find a plastic collar that runs down into the cell. The bottom of that plastic bit is where the acid should sit.
                            86 Lincoln Town Car (Galactica).
                            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                            91 Lincoln Mark VII LSC grandpa spec white and cranberry

                            1984 Lincoln Continental TurboDiesel - rolls coal

                            Originally posted by phayzer5
                            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                            Comment


                              #15
                              My dad always told me that when you put water in the battery put enough till you see "chinaman's eyes" and stop. He was an electrical engeineer that is how he knows.

                              Comment

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