[xj40] Testing a door lock actuator motor

XJ40
1

Test XJ40 electric door locks

Here’s what I learned troubleshooting an inoperative RF door
lock on my 89 XJ40 LHD. This post is for the archives, in
hope it will assist someone else experiencing an electric
door lock problem in future.

Operating properly…

Locking/unlocking either front door lock with the key locks
and unlocks the other 3 doors

Pushing the dash panic lock switch locks all the doors and
closes the sunroof.

Holding the key in locked position in either front door
(locks the other 3 doors, and) closes the windows and sunroof.

In my case, locking/unlocking the driver door lock did not
lock/unlock the RF passenger door, and vice versa.

Testing the right front door lock:

For purposes of this discussion…
With the LF door lock actuator unplugged, orient it’s
harness plug so you are looking into it’s open end at
the pins, a pair of pins on top, and the remaining
trio of pins on the bottom.
Start with the left top pin, call that pin 1 and
proceed clockwise, numbering the pins 2 through 5,
respectively.

Pin 1 has a yellow wire w/orange stripe
(senses lock position?)
Pin 2 has a purple wire w/red stripe
(senses lock position?)
Pin 3 has a purple wire w/pink? stripe
Pin 4 has a purple wire w/white? stripe
(activate the lock motor in either direction)
Pin 5 has a black wire w/white? stripe
(ground?)

  1. Consider the unplugged connector attached to the actuator…

    • attach test leads from the positive and negative
      battery terminals to pins 3 and 4… the lock actuator
      should move;

    • reverse those connections on pins 3 and 4 and the
      actuator should move in the opposite direction.

    If powering these 2 pins does not elicit actuator
    movement, this likely means the actuator is dead
    and needs replacing. This was the case on my car.

  2. Consider the receptacle this plugs into on the harness,
    and number each socket with the same number as the pin
    that fits into it.

    Using a multimeter on an appropriate scale to measure
    12 volts, I found that:

    • socket 2 has 6 volts with the car doors locked and
      socket 1 grounded.

    • With the car doors unlocked, those 2 sockets reverse
      and now socket 1 has 6 volts with socket 2 grounded.

    • There will not be any voltage across any other pairs
      of sockets.

    You could connect the multimeter across sockets 3 and 4
    and you should measure either +12v or -12 volts
    momentarily as a lock key is turned, depending on whether
    the key is locking or unlocking the doors.
    Test 1, above, indicated my problem was a bad
    acuator motor, so I did not try this test.
    If you don’t see a 12v needle jump on this
    test, then I’d suspect a harness problem or a central
    lock controller problem (it’s a black box under the
    passenger dash, next to the console).

Hint: don’t replace door upholstery for a day or two, until
you are certain things work properly–
84 XJS, 89 XJ40
Santa Barbara, CA, United States
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2

In reply to a message from WayneC sent Mon 6 Feb 2006:

nice job, Wayne … &:-))

only thing I would add is that the ‘‘panic switch’’ should also
close all the windows when activated …–
The original message included these comments:

Here’s what I learned troubleshooting an inoperative RF door
lock on my 89 XJ40 LHD. This post is for the archives, in
hope it will assist someone else experiencing an electric
door lock problem in future.
Pushing the dash panic lock switch locks all the doors and
closes the sunroof.

–
&:-)) Paul '88 XJ6 VDP 130k & '88 XJ6 VDP 180k
Garland, Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !