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Discussion Starter #1
Still trying to figure out the problem listed in this thread (in case you missed it)...

http://forums.tccoa.com/showthread.php?s=&threadid=12807

The problem definetely lies within the small black plug, and according to the wiring diagram, it has something to do with these pins...(from what I can figure)...

(open)
Luggage Compartment Door Solenoid Feed
Battery Saver Input
Battery Saver Output
Battery Saver Output
Park Lamp Input
Battery Power 1
(open)
Luggage Compartment Door Solenoid Feed
Battery Saver Input
Park Lamps Output
Battery Power 2
Horn Relay

What's this "battery saver"? Anyone heard of it?

Like it's posted in the thread above, locks, lights, and horn have been possessed by this. This is the plug that seems to be causing the problem. When it's not plugged in, the car acts fine, but I don't have any of the things that I should (power locks, interior lights, etc). How could this plug tie into the locks and such? Any help is much appreciated.
 

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Do you have an anti-theft device from the factory? That would affect things.

I have some info from a 1989 EVTM, which may have some differences, but I think it would be mostly the same.

The door locks should be wired through the keyless module, and the anti-theft (if you have one) is connected too.

I think that the power for the door locks enters the keyless module first, and then it passes through the lock actuators to ground when you use the lock switch (or the keypad).

The trunk lock solenoid can be powered through the keyless module, or through the switch in the glove box (which bypasses the module).

So, all these things are definitely related to the system.

The 89 keyless module got power at six connector pins. Three were always hot, two were hot only in run, and one was switched by the door handle switches. Clearly, you are getting power through at least some of these wires. And it looks like it's getting to ground somewhere it shouldn't.

I hope this helps somehow. This system's pretty complex, and I'm looking at an 89 book with no remote option, so anything I said may vary from what you've got. But the basics should be the same.
 

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Discussion Starter #3
It doesn't have the factory alarm, it just has the lock, unlock, trunk, and panic options on the remote. I want to say that it's not the door lock's causing the problem seeing that they are on the other plug, as are the interior lights. The part I don't understand is that they don't work.

Took the module itself apart. On the board, there seems to be 2 melted spots around the chips at "IC3" and "K6". I'll get a pic up in a few as to what I'm talking about.
 

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Discussion Starter #4
Here's a shot of the board...sorry, a little blurry...



This is what I can get from it...

A) You can't really tell, but there's a melted spot on the side.

B) K6...what I can tell, the label for the chip at A.

C) Appears to be majorly melted on the top and somewhat on the side. On the underside of the board, there's a black spot where you can tell it got really hot.

D) IC3...what I can tell, the label for the chip at C.

If someone can find what these "K6" and "IC3" circuits correspond to, it could be a big time saver. Thanks again.
 

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That's *EXACTLY* what my blown modules look like! That big square "A" is a melted relay and should be sitting flat on the board. Your module is toast! A new replacement is ~$250. - look for a used one if you can, but open it up first to be sure it also isn't toast.

What's happening in mine is that the underhood short let to other parts of my wiring harness melting/shorting out. I found about a foot long section of wire in the harness under the driver seat that had melted away so bare wire was shorting there also. 'Fixed that, but I still have a short in the system - I'm virtually positive it's behind the left kick panel.

Some weird way Ford set up the wiring bypasses the fuses in certain conditions, so no fuses blow, but the short just goes on to start melting/blowing things. Our situations seem virtually identical - I've been trying to track this down for over a year, including taking it to the dealer, and still haven't got it resolved...
 

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From my wiring diagrams, it looks like there are 4 pins entering the keyless module that are on 15A fused circuits. And one at 20A. I think it may be enough current to fry your board, but not enough to blow a fuse.

Maybe some current is getting in the wrong way past a failed diode. Like the "door ajar diodes" located in the trunk near the module.
 

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Discussion Starter #7
S_Mazza said:

Maybe some current is getting in the wrong way past a failed diode. Like the "door ajar diodes" located in the trunk near the module.
Ok, I don't know that much about electric and these "diodes" you're talking about. Details please. Thanks.
 

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The battery saver would probably be the thinger that shuts the interior lights off if left on for more than 45 mins?
 

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Sorry it took me this long to reply. A diode is like a one-way valve for electrical current. There are a couple types, but this is the main use, and the one I'm talking about here.

(LEDs are light-emitting diodes, so current only goes through them one way ... that's why they have to be wired in a certain way. And when the current passes through, they emit light.)

About the "door ajar diodes" ... I'm not guaranteeing this is the problem, but I'm saying that, if the problem isn't in the keyless module itself, it must be in the wiring. And, if you don't see any obvious problems with the wires itself, then maybe it's one of the specific components in the wiring system (like diodes).

So, take this with a grain of salt, but one thing I noticed on my 1989 EVTM diagram is that the door ajar switches are wired into the Keyless Entry Module and the Passive Restraint Module. There are a couple of diodes in the circuit, between the switches and the Keyless Module. I was just thinking, if the diodes failed, current might be able to pass through the Passive Restraint Module and run into the Keyless Entry Module. Which would be a reverse current flow, and I thought that might cause problems.

So, it's just a suggestion of something to check. Some voltmeters have a diode-test function built in.

My EVTM says they are in the wiring harness, "230mm (9 inches) from passive restraint module." (Which is in the trunk near the KEM.)

Also, do these Thunderbirds have a battery saver feature? My 89 doesn't. Maybe after 94 they do; I don't know.
 

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Discussion Starter #10
Thanks a lot...definetely some good info!

This makes me wonder now. Before (this was a good while back) the "int lamps" fuse was blowing (10A fuse), and I didn't think about it too much and wasn't wise to what could happen and put a 20A in and it was fine. Well, I could put any 10A fuse in I wanted and it would blow immediately. I could hold in on the button in the door jamb that controls when the interior lights come on and makes the "door ajar" lights come on, and put the fuse in, and it would not blow. BUT...as soon as I released the button to make it think the door was "ajar", the fuse would blow.

Might be a good place to start checking.
 

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Discussion Starter #11
Just another question about the diodes....What exactly do/would they look like? And is there anyway to visually tell if they are bad or any way to electronically test them?
 

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regular diode:

Symbol: --|>|--

it looks like a little cylinder with a band to indicate the cathode. Power flows from the anode to the cathode, but not in reverse (unless you really cram it in there, but that doesnt apply here)
 

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to test, hook up a ohmmeter to it. In one direction, it should be infinite resistance, in the other, very little.
 

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Yeah, or a multimeter may have a special mode for diode testing, in which case, just follow the directions. The side with the stripe is negative, so as Vegeta99 said, all the current should be flowing from no-stripe to stripe.

Here is a picture of a typical diode. (I think yours may be a little bigger.)

http://learning.media.mit.edu/projects/gogo/new/parts_images/diode.jpg

I am studying my EVTM right now to try and help some more. This stuff is tough; I'm no electrical engineer. But I'm sort of hooked on this problem, and I want to see it solved. Plus, I would love to know how to fix it, in case it happens to me!!!
 

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Hey there. I was reading those diagrams a little more the other night, and thinking about what you said. I am leaning in a little different direction now. First, from reexamining how the diodes are connected into the system, I'm less inclined to think they are the problem (although they certainly can fail from time to time.) Second, what you said about the problem you had with the interior lighting struck me a little. In my manual, the "Int Lamps" fuse is 15A, not 10A or 20A. Second, I can't see 6 or so lightbulbs pulling 10A and blowing a fuse. I think you probably have a short somewhere in that lighting circuit.

Also, I think the switches for the "Door Ajar" lamp and the interior lamps are separate ... 1 in the doorjamb, and 1 in the latch itself. So I think the "Door Ajar Diodes" and the interior lighting (activated when a door is ajar) are in 2 separate circuits. I will look at it some more.

I would start with that button on the door jamb and all the wiring in that circuit.
 

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Discussion Starter #19
Haven't really had any chance to work on it. Between being busy with work and school and just cold weather in general. Been doing a lot of thinking still. Might have a guy that knows a lot about this help me before too long.
 

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Solved!

After doing some looking, I got curious about the underhood light. Something about connection at the back of the hood, where it disconnects, didn't look right. Got an old toothbrush and scrubbed away all of the nasty buildup. One of the wires was completely stripped and half-way pulled out, the other wire was partially stripped. The problem was here all along, a simple short. Luckily nothing else was damaged in the ordeal.

The fix was simple. I just took the whole light and harness out. Went to the junkyard, found the last MN12 that had a box like mine in it...94 Cougar. Came back home, plugged it in, and no problems, everything works fine again. Then the next problem...my remote didn't work. Figured that each box is programmed with certain remotes. After some guidance from another member, I found out how to reprogram the remote for the box.

To reprogram the remote...

1- Turn ignition to ON or ACC. Make sure there are no lights on in the car.

2- Near the module in the trunk, there's an oval plug with 2 exposed pins on it.

3- Jump these pins together with a paperclip or something. Locks will lock and unlock to start programming.

4- Push any button on the remote. Locks will cycle again to confirm programing.

5- Turn ignition off. Locks will cycle once again to end programming.

Simple as that. Everything's back to normal - remote, lights, locks, and all. You really can't appreciate these things until you don't have them. Glad this is over.
 
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