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Thread: Keyless Entry and Lighting Issues

  1. #1
    Carthago delenda est Lutrova's Avatar
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    Default 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?

  2. #2
    I'm an air-conditioned gypsy gadget73's Avatar
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    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

  3. #3
    Carthago delenda est Lutrova's Avatar
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    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 Thumbnails Attached Thumbnails EVTM 10 - Reading Lights Ground.jpg  
    1987 Lincoln Town Car - Signature, "Prudence"

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    Carthago delenda est Lutrova's Avatar
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    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"

  5. #5
    I'm an air-conditioned gypsy gadget73's Avatar
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    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

  6. #6
    Carthago delenda est Lutrova's Avatar
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    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 Thumbnails Attached Thumbnails 200402 Electronics 3.jpg   200402 Electronics 2.jpg   200402 Electronics 1.jpg  
    1987 Lincoln Town Car - Signature, "Prudence"

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    I'm an air-conditioned gypsy gadget73's Avatar
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    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

  8. #8
    Carthago delenda est Lutrova's Avatar
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    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 Thumbnails Attached Thumbnails 200427 Module Sealed.jpg  
    1987 Lincoln Town Car - Signature, "Prudence"

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    Beater gonna beat sly's Avatar
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    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
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  10. #10
    Carthago delenda est Lutrova's Avatar
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    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"

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    Beater gonna beat sly's Avatar
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    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)
    Quote Originally Posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Quote Originally Posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

  12. #12
    I'm an air-conditioned gypsy gadget73's Avatar
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    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

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    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.

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    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"

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    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.

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    I'm an air-conditioned gypsy gadget73's Avatar
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    It may have sorted itself from simple use. CO is Circuit Open, thats the usual fault you'll get. Dirty spots on the resistor in the tank will make it flash that. Sometimes running fuel through it so it moves across that spot will be enough to polish it. My Continental does that randomly, used to be a lot worse but I still occasionally get 'CO' between about 11 and 20 gallons.

    One thing I've noticed with mine, if I fill it with the engine running it takes a long time for it to increase. I once drove for 2 hours and it "made" about 6 gallons of fuel. I put in 14. Shut it off for a few minutes and suddenly it was up 11 gallons, which is about right if you account for fuel used during the drive.

    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

  17. #17
    Carthago delenda est Lutrova's Avatar
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    I spoke too soon on the fuel gauge. It's still reading all over the place. Maybe it's correct sometimes, but it's hard to tell.

    Went to a junkyard today to look at a very intact 86 Town Car. This thing still had the original floor mats and the little black pieces on the ends of the intake plenum. I honestly felt bad pulling parts off of it. But I eventually got over it and grabbed a keyless entry module, trunk pulldown motor, 'Premium Sound' head unit, and digital fuel sending unit. The keyless module and trunk motor are already installed and seem to be working. It feels like quite a luxury being able to open the trunk without touching a key. I don't really understand what's so special about the soft close, but I guess it's a cool party trick.

    Hopefully this sending unit will do the trick for my fuel gauge. I measured resistance between 0-196 Ohms, which seems like it's in the ballpark of the 5-205 I saw posted somewhere, and the resistance seems to increase smoothly. Are there any other things I should be checking or doing before swapping it in? And how low should the tank be to keep from making a mess? Half? Less?
    1987 Lincoln Town Car - Signature, "Prudence"

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    I'm an air-conditioned gypsy gadget73's Avatar
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    I put one of the trunk closers in my base model that didn't come with it. Its entirely a "oooh, lookie at the fancy car" thing. Functionally the latch I removed is probably a better idea.

    make sure the float floats.


    Well under half would be appropriate. Probably 1/4 would be safe. Replace the O ring under the sending unit too, they seem to grow when removed and never go back together neatly.

    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 SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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

  19. #19
    The Brown Blob 87gtVIC's Avatar
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    I opted for the trunk muncher on my vic as I added new weatherstripping and I could no longer get the trunk to close and have the correct body lines. This gently sucks the trunk down the properly adjusted height where everything lines up. And its cool.
    ~David~

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    But, that's just coming from me, this site's biggest pessimist. Best of luck

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    Carthago delenda est Lutrova's Avatar
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    I've been digging into the fuel gauge issue some more and I'm starting to think the problem may not rest with the sender. Resistance on the sender currently installed reads correctly based on how much I figure is still in the tank. The connector at the sender also looks clean; I had my mechanic look at it a year ago and he must've added some dielectric grease. Turning the key to accessory - not triggering the fuel pump - will give a different reading at the gauge every time. The distance to empty estimate seems to remain consistent with whatever the fuel gauge is showing.

    Because the fuel gauge reading changes without any possible movement in the tank or sender, I figure the issue must be somewhere else. My EVTM says there are two connections between the sender and gauge, one "behind left hand side of instrument panel" and the other right at the fuel gauge/speedometer. Plus the ground in the trunk by the antenna. The connector to the fuel gauge would require, I assume, pulling the instrument panel. But is the other connector accessible from below without pulling apart the entire dash?

    I assume the troubleshooting procedure would be to check resistance at both connectors leading to the gauge for similarity to the sender? Or will resistance between these connectors at the dash and a body ground differ from the sender? And if resistance remains constant all the way up the chain then the gauge is faulty?
    1987 Lincoln Town Car - Signature, "Prudence"

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