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    Keyless Entry and Lighting Issues

    I have an 87 Signature Town Car that has its fair share of electrical issues. The digital fuel gauge jumps all over the place. The message center occasionally dims. Cruise sometimes resumes when using the turn signal or flashing high beams. I had hoped doing the 3g alternator upgrade might fix some of these problems, but one month later they persist. Two issues that I'm currently interested in pursuing are as follows:

    1) The keyless entry keypad is mostly working except for the trunk release and drivers door unlock. When entering the five digit code nothing happens until I hit 3/4 and all doors unlock, including the drivers door. But entering the code alone won't just unlock the drivers door. (This initially had me thinking I had the wrong code when I bought the car. I ended up making a list of every possible code and entering them with my brother - to no avail. It was only a week later when I thought to try unlocking all doors that I discovered the code printed on the module behind the glove box was correct all along.)

    Similarly, entering the code and hitting 5/6 won't pop the trunk. The soft-close motor is broken and has been unplugged, but the button in the glove box will still release the lid.

    All five keypad buttons light up when pressed and can be used for entering codes. And both the drivers lock and trunk release work through other means, so I feel like I should be able to rule out component failure at both ends. But never having done electrical work before, I'm not sure where to begin troubleshooting this.

    2) Both opera lights and the rear reading lamps occasionally get very dim. I haven't nailed down anything that might cause it to dim or bring it back. I just occasionally notice the opera lamps not lit when looking in the mirror or see the reading lamps just barely on when getting in or out. The problem seems to happen whether the car is off or on. I did replace all four bulbs with LEDs some time ago, though I didn't have the car long enough at that point to say whether the problem preceded that project or not. I've also replaced most other bulbs with the same LEDs and haven't noticed an issue on any other circuit.

    From searching through other threads it seems that some interior lights ground through screws or bolts which can come loose over time. But between these four bulbs, the opera lights must ground directly into the body and the brackets holding the reading lamps are fastened back onto the vinyl/plastic interior panel. Is there another ground somewhere that could've come loose?
    1987 Lincoln Town Car - Signature, "Prudence"

    #2
    Inside the keyless entry module are some small relays. One is for trunk, one is for driver's door, one is for the rest of the doors, and the last is to kick the interior lamps on when you use the keypad. Pretty fair bet one or more are crusty. I've pulled those modules apart and carefully polished the contacts on tbe relays with strips of paper before.

    Pull the keyless module. Once out, you should see plastic tabs holding the case together. Pop those and slide the card out of the box. You'll find the relays inside. Put a sheet of paper between the lower contact and the moving finger, very gently push down on the moving finger and pull the paper out. Do that until it stops leaving black streaks on the paper. Re-assemble the module and see if that takes care of the problem.


    random dim in the rear lights sounds like a flaky power feed. Pretty sure they do not share a ground being so far apart. I don't have my EVTM handy so I'm not sure where the feed to those is exactly. The reading lamps and opera lights aren't on the same power feed though, so it must be some connector that both pass through thats gotten funky. Fair guess its someplace in the driver's side kick panel area but that doesn't narrow it down much.
    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
      Thanks, Gadget. I'll pull the module tonight and see how gingerly I can be pulling it apart.

      I looked through my EVTM. (I own a copy, but reading these diagrams is like deciphering Chinese to me. Just like architectural electrical drawings.) It appears those fours lights do share the same ground, which is on the left side of the trunk. So I think I'll start by checking that and seeing where I end up.
      Attached Files
      1987 Lincoln Town Car - Signature, "Prudence"

      Comment


        #4
        A quick look in the trunk revealed a very loose ground connection right above the wheel well. So I'm willing to declare victory on the lights until proven otherwise.

        I'm having a little trouble removing the keyless module. It seems almost impossible to get at one of the two screws holding it to the bracket, but now that I'm back in the house and reviewing the shop manual it seems that bracket should rotate down to give access to both screws. It's a real pain though they're both facing toward the firewall. I'll give it another shot in the morning - maybe a little daylight will help the situation.

        If the half of a sticker saying "... NOT ... SEAL" is any indication, I won't be the first person to open this module.
        1987 Lincoln Town Car - Signature, "Prudence"

        Comment


          #5
          huh, wouldn't have figured a common ground but the book tells the story.

          and yeah getting that module out is kind of a PITA.
          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
            Turns out getting at those screws was a non-issue when the bracket just unhooked from the panel after a little monkeying around. It's amazing how rusty the bracket is for something tucked away under the glove box. I assume that's from condensation in the cabin over the last 30 years.

            The two cards, unfortunately, are pretty firmly fixed to the inside of the case. I don't see any screws inside so I'm guessing they've somehow corroded to the plastic. There's certainly a good amount of corrosion on the contacts for the wires. I'd try strongarming them out, but I can see a ribbon cable and two plastic supports, so it looks like they both slide out at the same time or something breaks.

            The four copper coils are, I'm assuming, the relays? Is it possible to get at what I need to clean with them still in the case?
            Attached Files
            1987 Lincoln Town Car - Signature, "Prudence"

            Comment


              #7
              hm, I don't remember having much issue getting the card out once the end cap was off. Pretty sure there are no screws or glue or any of that. Maybe needs a jiggle or something to persuade it? Been a number of years since I was into one of those modules so I might be forgetting some retainer tab or whatever. I don't remember having any special trouble with it so if there is another thing holding it together it should be fairly easy to find. What I'm remembering of that keyless box was a single board, not a stacked board like that though. Last one I did out of a Towncar was an 86, and not mine. Entirely possible I'm just working with faulty memory here. If that has the keyless entry code on it and your power locks do not work without it plugged in, thats the magic box.

              yeah the copper things are the relays. If you can get in there to clean the contacts that will do it. Just don't push down on them hard, the contacts aren't real stout. It wants just enough pressure to make the paper drag across the contacts.
              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


                #8
                Well I gave it the old college try, but there was no budging those cards. So I did the next best thing and took my Jap saw to the case. It wasn't the cleanest operation but it got the job done. I managed to clean the contacts on 4 out of 5 relays, though none really had any buildup. After sitting on my desk for several weeks I finally sealed the case back up and threw it into the car.

                ...And there was no change. So either the issue is somewhere else, either in the module or wires, or I didn't clean it properly. Either way, it looks like these modules run about 30 bucks on eBay, so next time I'm bothered by it I might just try swapping it out for another.

                Switching gears, is the light for the driver's mirror thermometer serviceable? I thought I'd read somewhere that it's illuminated by a fiber optic cable running back to somewhere in the interior. But elsewhere it appears there might be an LED inside the unit.
                Attached Files
                1987 Lincoln Town Car - Signature, "Prudence"

                Comment


                  #9
                  If I remember correctly... The light source is inside of it. The only lines coming out of those are the electrical connectors for the power movement, heated (if equipped) and light for the thermometer.
                  If I don't remember correctly, I'm thinking of the early 80s version and the later version is different (I don't think it is).

                  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


                    #10
                    If it's internal to the thermometer then it sounds like there's no replacing it. That seems like an oversight on someone's part. C'est la vie.

                    One thing I noticed today after reinstalling the keyless module is my Alarm light now flashes when I get in. I've owned the car for close to a year now and I didn't realize it had an alarm. Looking through the EVTM it doesn't appear the keyless module really interacts with the anti-theft, so I'm guessing there was a loose ground that I reconnected under the glove box when putting things back together.

                    I don't really know how useful the anti-theft on these cars is, but I suppose accidentally fixing it might be a silver lining to this whole effort.
                    1987 Lincoln Town Car - Signature, "Prudence"

                    Comment


                      #11
                      It may also just be mounted at the back end and accessible from the hole to the door. Would have to take it off to find out. It's been at least 7 years since I've seen one now, having sold the car I had with one.

                      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


                        #12
                        never had one of those lights quit, so never had cause to figure out how to replace it. The thermometers don't typically come out nicely so I would advise not messing with 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


                          #13
                          I had one of those lights go out. Easier to replace the whole mirror assembly especially with an older car, where parts have stuck in place.

                          Comment


                            #14
                            I wrote in the initial post how one of my longstanding electrical gremlins was the digital fuel gauge. Sometimes it would read high, sometimes low, and sometimes I would watch it increase. Occasionally the cluster flashed in what I believe is some sort of error code.

                            Well I don't want to call it prematurely, but driving around a bit for the first time since February, it looks like the gauge might be reading fuel correctly. The only thing I did that might've affected the sender was tightening a couple grounds in the trunk near the antenna. But does this make any sense? I would think that if the sender wasn't properly grounded it might send no signal at all, but the level jumping around would seem to indicate some fault with the sender itself?

                            Of course if it's fixed then I'm not complaining. But I don't want to start to rely on it only to find myself stranded out in the desert.
                            1987 Lincoln Town Car - Signature, "Prudence"

                            Comment


                              #15
                              There is a ground from the fuel tank wiring that is in the trunk somewhere; it should be shown in your EVTM. They don't ground to the tank itself and I don't believe they ran a ground all the way to the instrument panel (but I might be wrong...I am often enough, lol).
                              If the ground wire was loose, there would be a resistance between the sender and the body of the car, which the gauge would read as a change in fuel level.

                              It's possible that the float mechanism is sticky and it's not an electrical problem at all; I've seen on other cars where rust in the pivot caused the float arm to stick at certain levels for a bit longer than it should and give "flaky" readings. Running the car and moving the float might have wiped the rust off; but I'd lean toward it being a loose wire in the trunk, especially since Ford fuel level floats sit on cheap bent wires that don't rust up as much as more heavily constructed (*cougholderGermancarscoughcough*) arrangements.

                              Comment

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