actuators, a control unit and associated
wiring. Diagnosis can usually be limited to
simple checks of the wiring connections and
actuators for minor faults which can be easily
repaired. Since this system uses an electronic
control unit, in-depth diagnosis should be left
to a dealership service department.
Central locking systems are operated by bi-
directional solenoids located in the doors. The
lock switches have two operating positions;
Lock and Unlock. When activated, the switch
sends a signal to the door lock control unit to
lock or unlock the doors. Depending on which
way the switch is activated, the control unit
reverses polarity to the solenoids, allowing the
two sides of the circuit to be used alternately
as the feed (positive) and earth side.
Some vehicles may have an anti-theft
system incorporated into the locks. If you are
unable to locate the trouble using the following
general paragraphs, consult a dealer service
department or other properly equipped repair
facility.
1Always check the circuit protection first.
Some vehicles use a combination of circuit
breakers and fuses.
2Operate the door lock switches in both
directions (Lock and Unlock) with the engine off.
Listen for the click of the solenoids operating.
3Test the switches for continuity. Renew the
switch if there’s not continuity in both switch
positions.
4Check the wiring between the switches,
control unit and solenoids for continuity.
Repair the wiring if there’s no continuity.
5Check for a bad earth at the switches or the
control unit.
6If all but one lock solenoid operates,
remove the trim panel from the affected door
(see Chapter 11) and check for voltage at the
solenoid while the lock switch is operated
(see illustration). One of the wires should
have voltage in the Lock position; the other
should have voltage in the Unlock position.
7If the inoperative solenoid is receiving
voltage, renew the solenoid.
8If the inoperative solenoid isn’t receiving
voltage, check for an open or short in the wire
between the lock solenoid and the control
unit. Note:It’s common for wires to break in
the portion of the harness between the body
and door (opening and closing the door
fatigues and eventually breaks the wires).26 Electric mirrors-
description and check
2
1Most electric mirrors use two motors to
move the glass; one for up and down
adjustments and one for left-right adjustments.
2The control switch has a selector portion
which sends voltage to the left or right side
mirror. With the ignition ON but the engine
OFF, roll down the windows and operate the
mirror control switch through all functions
(left-right and up-down) for both the left and
right side mirrors.
3Listen carefully for the sound of the electric
motors running in the mirrors.
4If the motors can be heard but the mirror
glass doesn’t move, there’s probably a
problem with the drive mechanism inside the
mirror. Remove and dismantle the mirror to
locate the problem.
5If the mirrors don’t operate and no sound
comes from the mirrors, check the fuse (see
Chapter 1).
6If the fuse is OK, remove the mirror control
switch from its mounting without
disconnecting the wires attached to it. Turn
the ignition ON and check for voltage at the
switch. There should be voltage at one
terminal. If there’s no voltage at the switch,
check for an open or short in the circuit
between the fuse panel and the switch.
7If there’s voltage at the switch, disconnect
it. Check the switch for continuity in all its
operating positions. If the switch does not
have continuity, renew it.
8Re-connect the switch. Locate the wire
going from the switch to earth. Leaving the
switch connected, connect a jumper wire
between this wire and earth. If the mirror
works normally with this wire in place, repair
the faulty earth connection.
9If the mirror still doesn’t work, remove the
mirror and check the wires at the mirror for
voltage. Check with ignition ON and the mirror
selector switch on the appropriate side.
Operate the mirror switch in all its positions.
There should be voltage at one of the switch-
to-mirror wires in each switch position (except
the neutral “off” position).
10If there’s not voltage in each switch
position, check the circuit between the mirror
and control switch for opens and shorts.
11If there’s voltage, remove the mirror and
test it off the vehicle with jumper wires. Renew
the mirror if it fails this test.
27 Electric sunroof-
description and check
2
1The electric sunroof is powered by a single
motor in the roof behind the overhead console.
The power circuit is protected by a fuse.
2The control switches (tilt and slide) send an
earth signal to the sunroof motor when theswitches are pressed. Power is supplied to
the motor from the relay. With the ignition ON
but the engine OFF, operate the sunroof
control switch through the tilt and slide
functions.
3Listen carefully for the sound of the sunroof
motor running in the roof.
4If the motors can be heard but the sunroof
glass doesn’t move, there’s probably a
problem with the drive mechanism or drive
cables.
5If the sunroof does not operate and no
sound comes from the motor, check the fuse
(see Chapter 1).
6If the fuse is OK, remove the control
switches (see Chapter 11). Disconnect the
wires attached to it. Turn the ignition ON and
check for voltage at the switch. If there’s no
voltage at the switch, check for power and
earth at the motor. If power and earth exist at
the motor and there’s still no voltage at the
switch renew the motor. If there’s no voltage
at the motor, check the relay or an open or
short in the wiring between the relay and the
motor.
7If there’s voltage at the switch, disconnect
it. Check the switch for continuity in all its
operating positions. If the switch does not
have continuity, renew it.
8If the switch has continuity re-connect the
switch. Locate the wire going from the switch
to earth. Leaving the switch connected,
connect a jumper wire between this wire and
earth. If the motor works normally with this
wire in place, repair the faulty earth
connection.
9The sunroof can be closed manually by
inserting the T-handle spanner which is
located inside the overhead console. Insert
the spanner into the motor drive shaft and
rotate the shaft clockwise (see illustration).
28 Airbag system-
general information
Warning: Failure to follow these
precautions could result in
accidental deployment of the
airbag and personal injury.
12•14 Body electrical system
25.6 Check for voltage at the lock
solenoid while the lock switch is operated27.9 To close the sunroof manually, insert
the T-handle spanner in the motor shaft
and rotate it clockwise
3261 Jaguar XJ6
