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Mondeo mk2 central locking snag.

Discussion in 'Motors' started by SB118, 12 Mar 2010.

  1. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,637

    Location: "Sunny" Plymouth

    My auntie brought her mondeo over yesterday, the central locking is on the blink, the car won't lock.

    Push the lock button on the remote and nothing happens, turn the key and nothing happens.
    Push the unlock button on the remote and you hear the back doors (which aren't locked) run the unlock side of the motor)
    Pushing the rear doors lock/unlock handles makes no differance to the front of the system (this is normal i think) BUT if any back door is locked, it will unlock whenever any other unlock system is triggered.
    Use the driver side interior handle to lock and it instantly kicks back an unlocks. No other doors lock.
    Use the passenger side interior handle to lock and it instantly kicks back an unlocks. No other doors lock.

    Disconnect either front door and then you can lock the other front door, it doesn't trigger the locking system on the rear doors. Unlocking the front door still triggers the unlock of the rear doors.

    I've had the door cards off and door connectors to pieces, there are no frays/breaks in the wiring and no corrosion apparent on anything.

    I'm thinking central locking/alarm ecu? If i disconnect the central locking circuit from the box you can work all the doors manually without a problem (which is how i've currently left it), the car still starts and drives.

    If it's the ecu i've looked on the bay for another box and they are dirt cheap, BUT i think they need recoding? (based on the alarm unit being in the same box) They don't have the red key for the car, so i think they would need a complete key/locking/ignition ecu setup? (which would be more than the car is worth)

    Anything i've missed checking?
     
  2. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    My first port of call would be a door ajar sensor.

    With the Mk2 Mondeo you can put the oem alarm into a test mode. The easiest way to do this is open the bonnet and press the bonnet sensor in 5 times. It's a plunger looking thing on the drivers side near the headlight (from memory).

    The car should beep and or flash the lights when in test mode. Now, when you open or shut a door it also beeps or flashes (again from memory).

    Go around all of the doors and the boot testing for this.

    If you cannot get the alarm test to activate off of the bonnet open and close one of the doors 8 times quickly, the bonnet sensors are prone to failing so could be that you see.

    I had two Mk2 Mondeos and had to change a couple of sensors on each. They are under a tenner each from Ford.

    What age is the car? Older Mk2's shared Mk1 sensors which are a real pain to change (on the reverse of the lock in the door- lock out job). Newer Mk2 have the sensors on the catch (not in the door) and much easier to work with. If it's a newer mk2 you can press the sensor 8 times instead of opening and closing the door.

    Usually the boot sensor is in best condition as it's had the least amount of work.
     
    Last edited: 12 Mar 2010
  3. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,637

    Location: "Sunny" Plymouth

    Interior light behaved itself fine, 12 second delay thingy worked ok. Is that the same circuit?


    Dunno, she's taken the car back home now. I'll give it another look tomorrow.

    I'll give the alarm test a go then too.
     
  4. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    I would think so.

    There is a second sensor on the Mondeo which I had to change one of. It's the barrel lock position sensor.

    It basically detects if the lock barrel is in locked or unlocked position.

    With your key not doing a lot in the lock it's an idea?
     
    Last edited: 12 Mar 2010
  5. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,637

    Location: "Sunny" Plymouth

    If i unplug either of the front doors, the other door then locks/unlocks fine on the key, and unlock pulse also triggers the back doors to unlock (if i've locked them by hand), but it won't trigger the locking pulse for the rears.