Door locks are driving me crazy --- Help Me!

[MTCFORUM]

Well, I am officially going nuts!

I have had a door lock problem on my 98 Mark VIII for 3 weeks now. What it is doing is every once and awhile unlocking both doors while I am driving, once it starts it keeps unlocking the doors once a second or faster. It mainly happens when I hit the brakes on a bumpy road.

This lead me to believe that there is water somewhere in a plug or connection.

Here is what I have done to troubleshoot the problem:

Disconnected one at a time, first the drivers side, and then the passenger side, the following things:

Door switch – for obvious reasons

Door key sensor - (I think this is a 97-98 thing for sensing the PATS key) A double tap to this sensor will send an unlock pulse to both doors.

Keypad – It was brought up as a possibility

Lock Motors – thinking that if one was shorting out it may be back feeding it to the system

Alarm system – at this point who knows?

Then to eliminate all of the door rocker switches I cut the Pink/Green wire into the door computer right at the computer.

None of these has stopped the doors from unlocking, I am to the point now that I think it is just a bad door computer, but before I go spend the $$$ on a new one, I thought I would see if anyone had anymore suggestions that I could try.

Thanks, Don Brown

[MTCFORUM]

Do you get a "Door ajar" message at the same time? mine did something similar(not as frequent though) until I did the wd-40 trick.
Phil

[MTCFORUM]

Today mine went nuts for some reason. 3 times so far and it started today, when I start the car the trunk opens. I already checked the trunk button in the door but it's not stuck depressed. I hope it's just a tempary thing.

Lonnie

[MTCFORUM]

That was something I forgot to mention, I get NO error messages on the message center when this is happening.

Does anyone know if the Gen 1 and Gen 2 Drivers Door Module are the same?<BR><BR>
[Modified by DB, 6:48 AM 3/25/2002]

[MTCFORUM]

Hello,
I'm new to the group as i just found this web site today. Did you find a fix for the door lock problem. I've had the same thing happen but only about 3-4 times in the 6 years i've owned the car.

Todd

[MTCFORUM]

A friend of mine had a mid 90's Tbird...
the locks started cycling really fast then the wiring to the module in the truck burned up... {almost burned his car down}
he disconnected the battery before it caught fire.

Please make sure you get this solved, at whatever cost. it'd be a shame to have a car fire "while trying to figure it out".

he said, replace the Module in the trunk..{whatever that is}
Sorry for not providing MORE info, it was pulled from my feeble memory.

Kindest Regards
Tommy

[MTCFORUM]

I just had a mysterious electrial problem - it seems to have fixed itself. The moonroof was fully retracted. We had been driving around for awhile, temp was low 90's. When I pushed the close switch - nothing, when I pushed the open sw (roof was already open) I just got a click. The next day, just as I was ready to tackle the problem, damned, if it didn't work just fine...

I've been open & closing it regularly to see if I can duplicate prob. and I cant'

I'm just mentioning this here to acknowledge that these cars can have some quirky electrial prob's.

Now, the opening problem on your car. Let me think like a car (or a mechanic) for a second:
What's common to opening both doors??? Maybe also ask myself what's common to closing both doors?

Opening with the remote, I have to "Double click" to unlock pass. door.
Whoaaa, what about the L/U switches on the door pnls?? could a loose wire or "Bad" sw make this happen?? I'd double check that. The computer?? I know there's the auto lock drivers setting to automatically lock the doors after you put it in DRive for a few seconds. To me, that's a level of complexity of the car's electrical/CPU. You've got a transmission sensor to feed the CPU and programming to check to see if that "Option" is set and if so, then activate the "Lock Doors" circuitry. So, I'm wondering, L~M's got to have a quick diagnostic for the various CPU functions, other than the engine functions. Maybe someone else knows about this. I don't think it'd be the CPU anyway, not in this case.
I'd check those switches, if you can't see anything obvious, maybe wire a bypass or jumper around the switch (take it out of the circuit), one side at a time.
Please keep us posted. Maybe we can start a list of problems and solutions to these quirky happenings-

PS. pardon my inability to keep down the wordiness...but my computer seems to have an unlimited supply of ink. (humor, doesn't help the electrial problem - hopefully lightens the owner's reation)

[MTCFORUM]

I still get the trunk opening every we or so when I turn the key to start the car. Haven't really looked in to it though.
But the thing with the locks locking after the trans selector is placed in drive, it can be changed to work in different modes. I have the same set up on my tbird to and had the instructions on how to change it with the Keyless Entry Pad. But if I remember right it will lock in drive, lock when the pass. door is opened and shut or set it not to, instead of locking when trans is put in drive it can be set to lock after the car starts moving forward. I think there's one more setting. But my Mark, goes back and forth between the lock when placed in drive or sometimes it won't lock until the car is moving forward. I set my Tbird so it would quit locking when someone got out of the pass. side and shut the door. Since it was a bother to unlock it when they came back to get in. So it locks when the car starts moving forward if I had the trans still in drive. There's a little processer in the door on my Tbird that does all this. It might be the same on the Mark. I know a new one goes for 300 bucks so when mine when out I found one in the junk yard that the car still had the entry number sticker on the trunk lid.

Lonnie

[MTCFORUM]

I don't know about your case, but I have seen this twice on cars with the electronic key pad (an 86 or 87 cougar and a 90 Mk Vii) and both times it was becuase water had gotten into the keypad and was shorting it out in a way to activate the password and codes to lock/unlock doors and trunk.

You might try disconnecting the door panel computer in the trunk and see if you can isolate it. On those cars it was kind of a pita to do the change, the window track was in the way. Haven't ever tried it on an Viii.

Scott

[MTCFORUM]

Had this same problem with a 93 t bird and it turned out to be the keyless entry module in the trunk. Not sure if you have one on your mark. Just listen for a click in the trunk and find it that way. Hope this helps. Mark J.

[MTCFORUM]

As an update, I wound up replacing everything except for the wiring harness, but I still had the problem. I pretty much gave up on it and wired in a switch to kill the power to the door computer when it acted up.

Then one day out of the blue it quit doing it and has never done it again.

I am now reasonably certain that it is in the wiring somewhere, but I have no idea where to start looking for it, and as long as it doesn't act up again, I never will.