Land Rover Repair: 97 Disco remote locking problem, electrical fuse, strange assortment

Question
Tried to open my '97 Disco and all locks responded to the remote 'open' button
as expected except for the driver's door.  Same response when attempting to
lock vehicle - all locks respond appropriately except drivers door lock.  Has a
part died or can this be some kind of electrical fuse issue?  Is this a common
issue?  Can it be repaired without dealer assistance?

Answer
Hi Stephen,

yes, this is a common problem.  As to the cause, it can the lock actuator failing, the latch needing lubrication, electrical shorts due to corroded wires or connectors, the security ECU.  

The locking mechanism is based on an actuator and a strange assortment of metal wires.  One such wire is threaded and can be adjusted.  The wires are about the size of a bicycle spoke.

As for repairs, your best bet is to determine what component is causing the failure.  

A multimeter will determine if the actuator is getting any voltage.  If voltage is present but it does not work, chances are you found your fault.  If not, it gets very expensive as it could be either the security ECU or the BCU (body control unit).  These two components control other features on your Disco and it can get very nasty if you don't know what you are doing.  They are not very forgiving!!

If its not the actuator, it could be just a matter of a through cleaning (use brake cleaner or electrical contact cleaner) the latch a locking mechanism.  There is a long wire (spoke) that has the sole capability of being threaded for lock adjustments.  

IF you see that the actuator is powered BUT nothing is moving, then inside something has broken and you should replace the unit.

IF its within the locking mechanism, give it a good cleaning to determine if it helps, otherwise, replace it.

Caution.  When you remove the door panel to reveal the door frame and locking mechanisms, be very careful.  The door panel is held on by plastic threaded pins that can be easily ripped away from the foam door panel.  Use a tool purchased from a local auto parts shop to pry open seats and door panels.  When you do pry the panel off, be extremely careful and take your time.

Best of luck,

JohnMc