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88 Grand Marquis 5.0 w/ 100 amp alternator not charging?

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    88 Grand Marquis 5.0 w/ 100 amp alternator not charging?

    hey guys this is my first post to the forums.

    I have a 88 Grand Marquis 5.0 with a 100 amp alternator on it, when I got the vehicle the post that the main power cable bolted to on the alternator case was melted so bad that half the bolt had melted away so I removed the alternator and replaced it with one from a junk yard, and I repaired and replaced any fried wiring and fittings. I then tried to check for voltage at the battery with the car running and found the battery was loosing power instead of receiving a charge, so I removed and replaced the voltage regulator and checked for voltage at the battery again with the same result, battery loosing voltage, at this point I was stumped but had read on this forum that the in dash idiot light if bad can cause my problem so I tore the dash all apart and replaced the bulb as it did look to be a lil dim to me. again I started the car and checked for a charge going to the battery and again I found the the battery was loosing charge as the vehicle is running. At this point I am at a total loss as to where to begin looking next.

    Any assistance you guys can provide will be greatly appreciated as I need to get this thing running before the snow hits.

    Thanks in advance, Hustlewrench

    #2
    DO you have battery voltage at the post at the back of the alternator with the engine not running? If not, you've got a problem in the charge wire somewhere.
    Is the InstaClear windshield still in the car? Usually you can tell by the gold-ish tint the glass has. THe 100 amp alternator is typically only fitted to cars with that windshield. If the original glass isn't there, look for the relay for it. I think it lives over near the battery somewhere. If the windshield is removed, you have to change the wiring on that relay to bypass it. The instaclear system would switch the alternator from charging the battery to running full voltage output to the windshield in order to de-ice it. If that relay is smoked, it won't charge.

    I forget the specifics of bypassing it, but I know it was posted on here, and I think by 86VickyLX, roughly a year-ish ago.
    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


      #3
      Thank you for your reply and sorry it took me so long to get back to you, was hoping to post from work but had to much going on to find the time.
      When I installed the alt I did check for voltage at the post and yes it showed the same voltage as the battery at that time, was hoping to double check it today but as I said I got behind. As for the windshield yes it definetly is the heated windshield that copper color is unmistakable (and kinda cool looking). I dont believe it has been changed but honestly dont know if it has or not. There are a couple of relays that I can hear makin noise when I try to start the car but was unsure if that could be the problem. To be honest Electrical has always been my Achiles heel so any more input would greatly be appreciated.

      the alt I have has 1 small ground post then a plug with 2 wires in it and then the pos post, not sure what "g" the alt is.

      again thanks in advance.

      Comment


        #4
        that should actually be a 1G alternator with the external regulator on the driver fender (rectangular box with 5 or 6 wires coming out the bottom IIRC). Since you do have the insta-clear windshield, definitely keep the 1G, but like already posted... you'll probably need to find those relays and make sure they're not dead. Since I don't have access to info on those, I can't tell you where they are either.

        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


          #5
          You didn't by some chance have the defrost switched on when you were checking this did you? Doing that will cause the alternator to disconnect from the battery and run just the windshield.
          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


            #6
            ok Guys Im realy sorry its taking me so long to get back to you work has been a pain with tax time approaching. Anyway no I did not have the defroster on while I was checking for voltage, and since my last post we had the heated windsheild replaced and they did not put aheated window back in the car. Is there anyway someone can send me a pic of the relay I need to jump and a lil diagram on how to jump it. I have the whole day to get this figured out and I will be close to the pc the whole time so maybe I can get somewhere today with the help of theis great forum (w/extra cheese)

            Comment


              #7
              I have the Instaclear wiring diagram for an 89 (should be the same). What you're looking for is a B/O (black/orange stripe) wire from the alternator (should only be 3 wires and the other two are red and orange\light blue stripe. If you can follow that to the relay... just jumper the B/O wires together. This will forever bypass the instaclear. I would imagine it goes to one of the relays on the driver fender, but since I don't have one with the heated windshield, I can't go find it myself.

              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


                #8
                Its a reasonably large and odd looking relay if I'm not mistaken. I think it lives right next to the battery, as in you need to remove the battery to access it.
                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

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