What is there to go bad on automatic door locks?

Could be any number of thing's causing this problem . Knowing what all is involved in the locking an unlocking of the doors is key . Computer controlled by the BCM - body control module , relays ,wiring ,switches etc... Bad input from switch or grounding wire to the BCM could make the BCM think door unlock has been requested .
Door Lock System Components
The power door lock system consists of the following components:
• Driver door lock switch--Provides a switched voltage signal to the body control module (BCM) for both lock and unlock switch activations.
• Front passenger door lock switch--Provides a switched voltage signal to the BCM for both lock and unlock switch activations.
• Door lock relay--Located in the instrument panel (I/P) fuse block and controls the locking of all doors and liftgate.
• Door unlock relay--Located in the I/P fuse block and controls the unlocking of the passenger doors and liftgate.
• Driver door unlock relay--Located in the I/P fuse block and controls the unlocking of the driver door.
• BCM--Class 2 module which requires programming when replaced
• Reversible door lock actuators in each of the doors
• LOCK/MIRROR 10 A fuse--Located in the I/P fuse block, supplies power for the door lock switches and relays.
• DR LCK 20 A fuse--Located in the I/P fuse block, supplies power to the relays

Door Lock System Controls
The power door lock system can be controlled by any of the following:
• Power door lock switch activation
• Keyless entry lock or unlock command
• Delayed locking command
• Automatic door lock command
• Lockout prevention command
• An air bag deployment
Door Lock and Unlock Operation
When a door lock switch is activated in the lock or unlock position the body control module (BCM) will receive a voltage signal on either the door lock switch lock or unlock signal circuits.
The BCM, upon receipt of a lock switch lock or unlock signal, will switch the appropriate lock relay control circuit(s) to battery positive voltage. This will energize the appropriate lock or unlock relay(s). The relay will supply voltage to the door lock actuator lock or unlock control circuits to one side of the lock actuator. Since the opposing side of the lock actuators are connected to ground through the other lock actuator control circuit and the normally closed contacts of the lock or unlock relay, the doors and liftgate will then lock or unlock appropriately.
Three relays are used to operate the lock. Driver door unlock, passenger door unlock and all door lock. This is done to isolate the driver door lock actuator so it can be unlocked by itself using the keyless entry transmitter.

Automatic Door Lock Operation
This body control module (BCM) controlled feature can be personalized to driver preference.
The BCM will automatically lock the vehicle doors if the following conditions exist:
• All vehicles doors are closed.
• The ignition is in the ON position.
• The vehicle is shifted out of PARK.
The BCM will then unlock the doors when the ignition is placed in the OFF position.

The first thing ,hook up a professional type scan tool an check for DTC'S in the BCM
DTC Descriptors
DTC B3140 00: Driver Unlock Switch Circuit
DTC B3145 00: Passenger Unlock Switch Circuit
DTC B3150 00: Driver Lock Switch Circuit
DTC B3155 00: Right Front Lock Switch Circuit

DTC B3130 00: All Door Unlock Circuit

There was a related post in 2011 which may or may not help you troubleshoot .... from a Lincoln Master:
What is the fuse box number for locks 2003 Lincoln Navigator
If your fuse box is the same as this one ... then fuse #30 is the door locks ... plus other things. If your fuse is good (although I would test a new fuse in that slot to be sure) or if in inoperable stuff is different ... then you have some other issue going on

Take it to a shop. U fu--ed up royally doing the swap. If you had done the job correctly you would not be having this problem. Decent thing to do at this juncture is help your buddy pay for the correct repairs.

The first thing to do would be to check all fuses. Sometimes a very random blown fuse can cause this. Also unhook the battery for one hour to reset all systems, and try a jump start if you have not just to be sure it isn't a battery issue. Also try locking/unlocking the key driver's door a few times using the key in the door. If the fuses are good and the battery reset does not help, nor a jump or key in the door, then there are a few other things that can cause this such as bad key - try another one, bad brake light switch, the switch is above the brake pedal, shifter not fully in park (auto transmission only) - try moving it around a bit, bad transmission position switch, bad clutch switch, dead starter/solenoid/relay or bad ignition switch/cylinder/start button.

The 2005 Dodge Caravans have software problem in the BCM that causes the power locks to quit working. The only fix is to bring the van to a dealer for a software flash update.Read more: http://wiki.answers.com/Q/Where_is_the_fuse_located_for_power_door_locks_on_a_2005_Dodge_Grand_Caravan #ixzz271oz6ROB


disconnect the battery cable and pull the BCM fuse and do system reset and the door locks may work fine again.



also ro try to get the power door locks working. pull and reinstall (but not replace) all fuses and fuse blocks (but not the relays). The locks may start working after that.
Read more: http://wiki.answers.com/Q/Where_is_the_fuse_located_for_power_door_locks_on_a_2005_Dodge_Grand_Caravan#ixzz271pG2x7l

disconnecting and reconnecting the lamp and horn relays may fix same issue with the locks.
Several people suggested resetting the fuses under the hood, and it worked. Others tried unplugging and plugging back in the battery and that also worked for them.
Read more: http://wiki.answers.com/Q/Where_is_the_fuse_located_for_power_door_locks_on_a_2005_Dodge_Grand_Caravan#ixzz271pmOoHv

That sounds like a possible bad door lock switch to me. I have also seen defective door lock control modules cause the same symptoms. These things can also cause your battery to drain because it is probably also doing this when the vehicle is shut off. The power lock solenoids in the doors will also bedestroyed if it is allowed to continue.

If you cannot get it diagnosed and repaired right away, I recommend unplugging your door lock control module to prevent furter damage to the vehicle. Yours is located under the dash next to the fuse block. (See picture)

Just on one door? Maybe a bad solenoid in that door.
All the doors don't work? Look at your interior fuse panel. There should be a small metal fuse. Maybe two (one for power windows). That is not a fuse but a circuit breaker. Pull it out to reset it and reinsert it. There may also be a relay. Not sure where but I think it is behind the passenger kick panel. I would check the other things first before the relay.

yes this does happen,try disconnecting the battery and joining the leads together ,this often resets it other than that its either a new drivers door lock or the dealers to have it re programmed

To get the key out; look under the steering wheel for a plastic flat head screw. untwist it and then push the spring in and your key will be free. Then, go to your fuse box and remove the main fuses and you will hear the doors unlock when the system reset itself. Plug them back in and start your car. This just happened to me... seems the only things that were working were the navigation screen, headlights, fog lights, and reading light on the inside. Dash board was all dark except the engine light.

Could be the door unlock relay is bad . Has a Separate relay for locking the doors . You'll have to look in your fuse boxes for location .