No mechanical car door key. Battery dead as a doornail. How open door?

This hasn’t happened yet, but a friend of mine just bought a 2007 Lincoln Town Car and asked me about this because I work at auto auctions in my semi retirement, and am supposed to be an “expert” on this kind of stuff. Haven’t a clue on this one and the owner’s manual doesn’t address it.

Opening doors is all electronic, no outside insert for a key. Doors can be opened many ways…key fob numerical code on door etc…but no mechanical way to overide it except door handle on inside. Do have ignition and trunk keys.

Friend asked me …OK battery is dead as a doornail (left lights on or something). All doors are locked. How do you get in the car?

Maybe there is some kind of chip or something that will allow the electronics to work with a dead battery?

Would just remove the neg terminal of the battery and see what happens, but friend doesn’t want me to do that.

I’m sure Lincoln wouldn’t have such a potentially dangerous thing (suppose a kid was inside?)

Why don’t you call a Lincoln dealer and ask the service department?

if a kid is inside and can’t open it from inside, you break a window.

Is there a mechanical lock for the boot (trunk)? Some BMWs have the same problem and the cure is to open the boot and apply 12 volts to the terminals in the interior light. That gives enough power to operate the door locks.

That would work because there is a mechanical key for the trunk…would have to cut into some wires and have to be on a constant on circuit in order to back feed to the door electronics.

Still think if I disconnect the neg terminal, will find that the door electronics still work due to some kind of microchip. Maybe can talk friend into letting me try that.

It is hard to actually talk to a mechanic at a dealership and the salesmen will tell you the first thing that pops into their minds.

If you follow the link - you will see that finding and using the terminals in the light fitting will avoid any cutting.

I’m not a car guy…but I am an embedded systems guy.
Having a separate microchip to control the locks doesn’t remove the need for power. If the battery is well and truly dead, it won’t help.

It is possible, however, that a severely depleted battery would provide enough power to run such a microchip, but not do anything else useful. The lock almost definitely needs more power to actually move it - magnet, motor, etc.

If you can get to the battery terminals, what’s stopping you from jacking in a new battery through jumper cables and opening the door however it needs to be opened?

On my kids 1997 LTC the hood is a mechanical latch. If it’s the same on a 2007 LTC simply pop the hood and give the battery juice. The electronic keypad next to the key will then operate. You can also use a slim jim to pop the lock.

The guy bought a $40,000 book, and threw in a free car and he never opened the book. ( the book in question is the owners manual. RTFB)
Anyway every proximity key car I have ever seen has a keyway somewhere to get in. Usually in the drivers door. Sometimes the keyway is covered by a plastic cover.
The remote has the key that will open this door. Usually it is part of the remote typically the metal part where you attach it to you key ring. Look for a small push button or slide switch.

I agree with all of this, Rick - and BTW, does “5150” mean anything to ya? - but if the vehicle battery is dead, no proximity override is going to do much good.

Hood release is inside car. My old 72 Dart wasn’t like that but times have changed.

Only way to get to power is through trunk and inside light. That would work

Nothing on drivers door. Looked for that key on fob like Mercedes and I think BMW has. Not there on Lincoln.

I doubted a microchip would have enough power. I know it is enough to retain an odometer reading, but that would take very little power.

Thanks for all the replies and sorry for my stupidity. I had another chance to look at my friend’s car and there is a place for a mechanical key in the driver’s door handle.

Don’t know how I missed that the first time I looked at it.

Told ya. :smiley:

Sure does. I deal with them daily.

Maybe we’re talking across the point - if you mean a mechanical override key, sure. But any kind of proximity override requiring power in the vehicle, nope. Your post wasn’t clear which one you meant.

Rick: Are you thinking of the 5150 police code? 'Cause that’s what it means to me. :slight_smile:

Good pick-up line.