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2012 MKX come out to car unlocked?


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Hello All, New to the Form but on several other ford pages.. Have an odd one. Wife new to her car 2012 33,000 miles 2012 MKX. She locked her key fob in car last week and had to get the other fob to open doors. I was out of the country when this happen. I set up here key pad when I returned home. Code works all seems fine. The next day wife tells me while driving the locks cycled unlock and locked while driving. She went into work locked her car like she normally does by using the keypad on the door. She doesn't use the key fob. when she came out for lunch car was unlocked... Same thing happens after lunch. I took car into change battery since it is original for a 2012 figure maybe going bad. Well it did it to me while are work. Any ideas??

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Going from memory, there are four things that control the locks, the keypad on the exterior, the FOB, the lock button on the interior door panel and the auto-lock circuit when the car is on motion. Any of these could be shorting due to wire chafing or corrosion.

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That being said, as it happens while the car is parked, I would tend to not think any of these are at fault (except possibly the auto-lock). The lock sequence is controlled by the Smart Junction Box. (At least it was, it may be controlled by the Body Control Module in yours, being a later year). Whichever module it is, it may be developing a short (again corrosion, shorts or a failing IC).

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I believe that the various circuits should have a fault code associated with them, I would imagine that the Ford diagnostic tester may be able to narrow down the fault (if it is setting a code). Or may be it can see the problem when cycling though all of the four lock circuits. (With the tester connected, lock the doors with the FOB, interior door switch, etc.)

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Because of the complexity of several circuits involved, wiring, electronics and it's intermittent nature, I would recommend a dealer visit. It impinges on your safety and security and needs to be found.

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Thanks for the quick Reply!

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First it was the original battery so it needed changed regardless. I know some electronic can start to show signs if there is under voltage.

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Second i did change both key fob batteries as well figured it was worth a shot.

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All of this started with changing the keypad code to our own personal code. I am wondering if i have changed something in its interface while doing this. I have not had the locks cycle while i have driven it other then them locking once the vehicle starts to move. Which is the correct function. The only time i had a issue yesterday was when I locked the vehicle using the keypad and i came back out 2 hours later to it being unlocked. I locked them with key fob and came back out about hour and half later it was still locked.

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I have the vehicle today again see what happens today.

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Thanks everyone I will keep everyone posted once i determine the issue.

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Try this if possible:

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Take the fob out of range. Lock the vehicle with the keypad. Make sure it's actually locked. Wait 5 minutes. Go back and see if it's still locked or unlocked (all without an in range fob). If it was locked at first but is now unlocked then you know it's the vehicle not a fob.

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I don't think they keypad on it's own can lock or unlock anything - it just transmits the code to the BCM/SJB. So the only way for it to unlock the vehicle accidentally is if you had just entered your code and then it thought you pressed another button to unlock all the doors. Once the code times out no button presses (actual or due to a problem) would unlock the door.

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I'm still thinking it's a fob problem, but that is easy to rule out if the fobs are not in range when it happens.

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Just some random thoughts:

Maybe there is some dirt or grease on the inside of the driver's door handle causing it to trigger an unlock request.

Do you get the shift to park message (bad shifter) or door ajar warning?

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I once had an issue when I remote stated the MKX it would turn off immediately or after a few seconds, turned out the flexible plate under the start button of the fob had moved slightly and caused the fob to send wrong signals.

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Well all WE have figured out the issue with the help of all and some brain storming.. Bad Key Fob. I changed the batteries out a few days ago which was fine but I did not take the whole key fob apart. Sat down with a adult beverage and let the thinking begin. I took a part both Key Fobs to clean them and the contacts to see if one had shown any signs of corrosion on the circuit board. To my disbelief the metal contacts that is glued to the rubber button (unlock & lock) has came off and was siting on the board. Causing it to randomly unlock & lock. So looks like i might need to buy a new keyfob. Any ideas on best place to purchase and has anyone reprogrammed a new one? I tech still have two working keyfobs.

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Thanks all for the Help! These Forums are a life savor! :worship:

Edited by Schmidty1284
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