Jaguar XK 1999 User Manual

XK8

DATE

9/98

Amended 1/99

501-11

SERVICE

Convertible Top Electrical System –

Component Descriptions & Diagnosis

Remove and destroy Bulletin 501-11, dated 9/98.
Replace with this Bulletin.
A description of the convertible top system

opening and closing sequence has been added.

Issue:

This Technical Bulletin provides information which should enable the diagnosis and repair of
possible malfunctions within the electrical components of the power convertible top system.

Mechanical failures are not covered in this Technical Bulletin.

Action:

Refer to section below for component descriptions. Refer to page 5 for fault diagnosis. Refer to
Fig. 15.2 of the XK8 Electrical Guide for an electrical schematic of the convertible top system.

TECHNICAL BULLETIN

MODEL

VIN

1997 MY-ON

XK8 Conver tible

001001-ON

COMPONENT DESCRIPTIONS

Hydraulic Pump

Located in the right side of the luggage compartment. The pump can be operated in two
directions depending on the required direction of the convertible top (push direction - pistons
extend, pull direction - pistons retract). There is a separate fluid outlet for each direction since
the fluid returns through the other outlet which then functions as an inlet.

Convertible Top Hydraulic Cylinders

Located on each side of the rear seat, they are attached between the body and the convertible top
frame. When hydraulic fluid is pumped into the base of the cylinders the pistons extend, raising
the convertible top. Fluid directed to the top of the cylinders cause the pistons to retract, lowering
the convertible top.

Latch Mechanism Hydraulic Cylinder

Located above the windshield in the latch plate assembly, the cylinder controls the convertible
top latching mechanism which basically comprises a claw and two locking pins. The cylinder,
either locks or releases the latching mechanism. At the end of the convertible top closing cycle,
the claw engages the convertible top and pulls it into the latch position, where the locking pins
secure the convertible top in place. On receiving a request for the convertible top to be opened,
the cylinder retracts the two locking pins and opens the claw, releasing the convertible top,
allowing the convertible top cylinders to take over the convertible top opening cycle.

Date of issue 9/98 Amended 1/99 Bulletin Number 501-11 Page 1 of 10

Hydraulic Pump Control Relays

The relays are located in the luggage compartment fuse box.
When the Top Up Relay is energized, the hydraulic pump is in convertible top raising mode

(push direction - pistons extend).
When the Top Down Relay is energized, the hydraulic pump is in convertible top lowering mode

(pull direction - pistons retract).
The two relays are controlled directly by the Security and Locking Module (SLCM) located

below the fuse box in the luggage compartment.

Hydraulic Control Solenoid Valves (Latch Control Valve and Main Control Valve)

Located on top of the convertible top’s hydraulic pump, the solenoids are identified by colored
dots: Latch Control Valve = Blue, Main Control Valve = Orange.

Both solenoids are controlled by the Security and Locking Control Module (SLCM) which is
located below the luggage compartment fuse box. The solenoids control the flow of fluid to and
from the base of the hydraulic cylinders:

When energized, the Latch Control Valve allows fluid to be pumped into the base of the latch
mechanism cylinder to extend the piston. When de-energized, the Latch Control Valve allows
fluid to exit the base of the latch mechanism cylinder to allow the piston to retract.

When energized, the Main Control Valve allows fluid to be pumped into the base of the
convertible top cylinders to extend the pistons. When de-energized, the Main Control Valve
allows fluid to exit the base of the convertible top cylinders to allow the pistons to retract.

Convertible Top Switch

The switch is located in the center console in front of the radio.
When the switch is pressed it signals to the Body Processor Module (BPM) to either open or

close the convertible top. The BPM communicates the request via the SCP - BUS to the SLCM
for as long as the switch is held in the respective position.

There are five microswitches in total which inform the SLCM of the convertible top’s position:
The “Top Ready To Latch” Switch, “Top Latch Closed” Switch, and “Top Closed” Switch are

located in the latch mechanism, and are connected to the BPM which is located behind the glove
compartment.

The “Top Down” Switch is located on the bottom of the right side convertible top cylinder and is
connected to the SLCM.

The “Top Raised” Switch is located on top of the right side convertible top cylinder and is wired
in series with the “Top Ready To Latch” Switch.

The BPM notifies the SLCM of any change to the “Top Ready To Latch” Switch, the “Top Latch
Closed” Switch, or the “Top Closed” Switch via the vehicle SCP - BUS.

The functions of the microswitches are given in more detail in the section Operation of
Microswitches.

Page 2 of 10 Bulletin Number 501-11 Date of issue 9/98 Amended 1/99

OPERATION OF MICROSWITCHES

Overview
“Top Ready to Latch” Switch

and “Top Raised” Switch

When both of these switches are closed, the system signals that the convertible top is over center,
and that the top has contacted the latch claw.

“Top Closed” Switch

When this switch is closed, the system signals that the top has been successfully grabbed by the
latch claw.

“Top Latch Closed” Switch

When this switch is closed, the system signals that the latch has retracted successfully, and that
the locking pins are extended.

“Top Down” Switch

When this switch is closed, the system signals that the top is completely open.

Description

When the Security and Locking Control Module (SLCM) receives a convertible top action
request from the main control switch, the SLCM monitors each mechanical movement via the
microswitches as the convertible top cycles through its open or close operation. The
microswitches signal when the cylinders and latch mechanisms have completed each of their
designated operations.

“Top Ready To Latch” Switch: Latch Claw.

• When the claw is fully raised (open) the “Top Ready To Latch” Switch is ‘open circuit’.

• When the claw is in the lowered position (closed) the “Top Ready To Latch” Switch is
‘closed circuit’.

• On a convertible top closing cycle, the SLCM waits until the “Top Ready To Latch” Switch
and the “Top Raised” Switch are ‘closed circuit’ before it triggers the latch pins to close.

• On a convertible top opening cycle, the SLCM is informed that the convertible top has left
the claw when the “Top Ready To Latch” Switch switches to ‘open circuit’.

Note: The “Top Ready To Latch” Switch is wired in series with the “T op
Raised” Switch therefore, both switches must be closed before the BPM
input is grounded.

“Top Closed” Switch: Latch Claw.

• The “Top Closed” Switch informs the SLCM of the position of the convertible top.

• Before the claw lowers the convertible top into latch position, the “Top Closed” Switch is
‘open circuit’.

• When the claw has lowered the convertible top into latch position, the “Top Closed” Switch
switches to ‘closed circuit’.

• On a convertible top opening cycle, the SLCM begins to power the convertible top cylinders
when the “Top Closed” Switch switches to ‘open circuit’.

Date of issue 9/98 Amended 1/99 Bulletin Number 501-11 Page 3 of 10

• When the “Top Closed” Switch switches to ‘open circuit’ the hydraulic pump reverses
direction to open the convertible top.

“Top Latch Closed” Switch: Latch Locking Pins.

• When the latch claw has pulled the convertible top into latch position and the locking pins
are fully engaged, the “Top Latch Closed” Switch switches to ‘closed circuit’. In all other
conditions the “Top Latch Closed” Switch is ‘open circuit’.

• On a convertible top closing cycle, the SLCM waits for the “Top Latch Closed” Switch to
switch to ‘closed circuit’ confirming that the convertible top is closed, before raising any
glass at easy open, and sounding the chime alarm.

• The switching of the “Top Latch Closed” Switch to ‘closed circuit’ indicates that the
convertible top opening or closing cycle has finished, therefore allowing the hydraulic pump
to be switched off.

Note: The switches in the latch mechanism are monitored. If there is a
switch failure the instrument cluster will display “Convertible top Latch
Fail”.

“Top Down” Switch: Convertible top Hydraulic Cylinders.

• When the convertible top cylinders are fully retracted (convertible top lowered) the “Top
Down” Switch switches to ‘closed circuit’, in all other conditions the “Top Down” Switch is
‘open circuit’.

• When the convertible top cylinders are fully retracted, the switching of the “Top Down”
Switch to ‘closed circuit’ retracts the latch claw.

“Top Raised” Switch: Convertible top Hydraulic Cylinders.

• When the convertible top cylinders are fully extended (convertible top over-center in raised
position) the “Top Raised” Switch is ‘closed circuit’.

• In all other conditions the “Top Raised” Switch is ‘open circuit’.

• The “Top Raised” Switch when ‘closed circuit’ informs the SLCM that the convertible top
is over center and in a safe condition for the latch claw to pull the convertible top closed.

Note: The “Top Raised” Switch is wired in series with the “Top Ready To
Latch” Switch, therefore both switches must be closed before the BPM input
is grounded.

Page 4 of 10 Bulletin Number 501-11 Date of issue 9/98 Amended 1/99

CONVERTIBLE TOP OPENING SEQUENCE

Note: When operating the convertible top, the engine should be running to
maintain maximum battery voltage.

The following is a step-by-step description of the convertible top opening sequence. It can be
used for fault finding to determine at what stage the convertible top opening sequence was
interrupted, therefore giving an indication of which component is malfunctioning.

The table at the end of the description shows the varying conditions (on = closed, off = open) of
the switches, solenoids and relays as the convertible top goes through the opening cycle. The
numbers in the top row of the table refer to the following description steps.

1. When the convertible top opening sequence begins the relays and solenoids will be in the
off position, ‘Convertible top down switch’ will be the only switch in the ‘open circuit’
condition.

2. Pressing the convertible top switch will signal the Body Processor Module (BPM) to send a
‘Open Convertible top’ signal to the Security and Locking Module (SLCM). The SLCM
will open both rear quarter windows, and sound the chime alarm to warn that the
convertible top is about to open. (Note: the rear quarter windows will be powered for a
maximum of 3 seconds).

3. If the front windows are closed they will be opened slightly. The SLCM will switch on relay
‘Top up relay’ and the ‘latch control valve’, the latch claw will start to raise.

4. As the latch raises ‘Convertible latch closed switch’ followed by the ‘convertible top closed
switch’ will switch to ‘open circuit’.

5. When ‘Convertible top closed switch’ switches to ‘open circuit’ the SLCM will switch off
relay ‘Top up relay’ and switch on relay ‘Top down relay’. This will change the hydraulic
pump from push to pull mode to start the opening of the convertible top. When the
convertible top leaves the latch claw ‘Convertible top ready-to-latch switch’ and
‘Convertible top raised switch’ will be switched to ‘open circuit’.

6. When the convertible top has fully opened ‘Convertible top down switch’ will switch to
‘closed circuit’. The SLCM will sound the chime alarm, raise any windows which it had
lowered except the rear quarter windows, and switch off the ‘latch control valve’ causing
the latch mechanism to close.

7. When ‘Convertible top latch closed switch’ is switched to ‘closed circuit’ in response to the
latch closing, the SLCM will switch off the hydraulic pump.

1 & 23445556677
Main control valve OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF
Latch control valve OFF ON ON ON ON ON ON ON OFF OFF OFF
Top up relay OFF ON ON ON OFF OFF OFF OFF OFF OFF OFF
Top down relay OFF OFF OFF OFF OFF ON ON ON ON ON OFF
Convertible top ready-to-latch switch

& Convertible top raised switch.
Convertible top closed switch ON ON ON OFF OFF OFF OFF OFF OFF OFF OFF
Convertible top latch closed switch ON ON OFF OFF OFF OFF OFF OFF OFF ON ON
Convertible top down switch OFF OFF OFF OFF OFF OFF OFF ON ON ON ON

Date of issue 9/98 Amended 1/99 Bulletin Number 501-11 Page 5 of 10

ON ON ON ON ON ON OFF OFF OFF OFF OFF

CONVERTIBLE TOP CLOSING SEQUENCE

Note: When operating the convertible top, the engine should be running to
maintain maximum battery voltage.

The following is a step-by-step description of the convertible top closing sequence. It can be used
for fault finding to determine at what stage the convertible top closing sequence was interrupted,
therefore giving an indication of which component is malfunctioning.

The table at the end of the description shows the varying conditions (on = closed, off = open) of
the switches, solenoids and relays as the convertible top goes through the closing cycle. The
numbers in the top row of the table refer to the following description steps.

1. When the convertible top closing sequence begins the solenoids and relays will all be
switched ‘off’. The ‘Convertible top latch closed switch’ and ‘Convertible top down switch’
will be the only switches that are ‘closed circuit’.

2. Pressing the convertible top switch will signal the Body Processor Module (BPM) to send a
‘Close Convertible top’ signal to the Security and Locking Control Module (SLCM). The
SLCM will sound the chime alarm to warn that the convertible top is about to close.

3. If the front windows are closed they will be opened slightly. The SLCM will turn on the ‘top
up relay’ and the ‘latch control valve’, the latch claw will start to raise.

4. As the latch claw raises ‘Convertible top latch closed switch’ will go ‘open circuit’.

5. When ‘Convertible top latch closed switch’ goes ‘open circuit’ the SLCM switches on
solenoid ‘main control valve’; the convertible top will start to raise.

6. When the convertible top has fully raised it will touch the latch claw which will switch
‘Convertible top ready-to-latch switch’ to ‘closed circuit’, and the end of the convertible top
cylinder travel will switch ‘Convertible top raised switch’ to closed circuit enabling a signal
to be sent. The SLCM switches off the ‘Latch Control Valve’; and the claw pulls the
convertible top in to the latch position allowing the locking pins to engage, securing the
convertible top in place.

7. When the latch has closed ‘Convertible top closed switch’ and ‘Convertible top latch closed
switch’ will be switched to ‘closed circuit’, the SLCM will turn off the hydraulic pump,
sound the alarm chime, and raise the front windows.

8. Further pressure on the convertible top switch will raise the rear quarter windows.

1 & 234566 77 7
Main control valve OFF OFF OFF ON ON ON ON ON OFF
Latch control valve OFF ON ON ON ON OFF OFF OFF OFF
Top up relay OFF ON ON ON ON ON ON ON OFF
Top down relay OFF OFF OFF OFF OFF OFF OFF OFF OFF
Convertible top ready-to-latch switch &

Convertible top raised switch
Convertible top closed switch OFF OFF OFF OFF OFF OFF ON ON ON
Convertible top latch closed switch ON ON OFF OFF OFF OFF OFF ON ON
Convertible top down switch ON ON ON OFF OFF OFF OFF OFF OFF

Page 6 of 10 Bulletin Number 501-11 Date of issue 9/98 Amended 1/99

OFF OFF OFF OFF ON ON ON ON ON

FAULT DIAGNOSIS

Note: When operating the top, the engine should be running to maintain
maximum battery voltage.

Fault diagnosis is split into three sections, the most common top failures are listed under the
section Preliminary Checks. The vehicle should be checked using this list before consulting the
following sections. The second section Diagnosing Switch Faults deals with faults which occur
when one of the microswitches malfunctions. The third section is a list of top failures and their
possible causes. Refer to Fig. 15.2 of the XK8 Electrical Guide for an electrical schematic of the
convertible top system.

Preliminary Checks

Listed below are the most common top failures:

• Is the battery fully charged?

• Is the top pump switched to automatic? - check that the manual operation valve on the side
of the pump is turned fully clockwise.

• Are all the relays correctly seated in the luggage compartment fuse box?

• Check for blown fuses in the luggage compartment fuse box.

• Are all the connectors including the orange and blue solenoid connectors secure and
correctly fitted to the hydraulic pump?

• If the top has been manually operated ensure it has been returned to the automatic condition.

• If the mechanism claw is in the wrong position in comparison to the top’s position, it is
possible that the system’s logic has become confused. The problem can be corrected by
manually repositioning the claw, e.g. if the claw is in the raised position move it into the
lowered position.

Diagnosing Switch Faults

To use the table on the next page, read down the relevant column until a box is found that
describes the top malfunction. Once found, check that the description in the opposite box relates
to the malfunction when the top is operated in the opposite direction. If both descriptions agree,
then the problem is being caused by the listed switch or the harness/connectors linked to it.

The described top malfunctions assume that the top operation is starting from either the fully
raised and latched position or the fully lowered and latch retracted position. It is important that to
successfully diagnose some failures that the main control switch is depressed for up to 35 to 40
seconds. This allows the program logic to achieve ‘time out’ i.e. maximum time allowed for top
opening or closing to complete its cycle.

Note: Some switches have similar symptoms when the top is operated in one
direction, but no two switches have the same failure problems in both
directions.

Date of issue 9/98 Amended 1/99 Bulletin Number 501-11 Page 7 of 10

Problem While Top is Opening Problem While Top is Closing Possible Cause

‘Top Latch Fai l’ displ aye d on instr ument
pack when ignition is activated. Rear
quarter glass will lower, but latch and top
will not funct ion.

‘Top Latch Fai l’ displ aye d on instr ument
pack when ignition is activated. Top wi ll
lower and latch claw wi ll retract when top
is dow n, howe ver, on relea sing mai n
control switch the latch claw will raise and

Top raises and latches but chime alar m
does not sound . Rear qu arter gl ass wil l
not ra ise. ‘Top Latch Fail’ di splaye d on
instrument pack after operation.

Top Latch Fail’ displayed on
instrument pack when the ignition is
acti vated. Top rais es and la tches but
chime alarm does not soun d. Rear
quarter glass will not raise.

remain raised.
Top will lower but there will be a delay

before the la tch claw ‘ rapidl y’ retra cts, due
to a logic time-out. ‘Top Latch fail’ will

Top will function normally. (Top
down’ switch is not functional during

Top rais e operation) .
NOT be dis playe d on inst rument pack
after operation .

Top will function normally. Top will raise and engage in latch

claw, followed by a delay before the

latch claw ‘rapidl y’ retracts. Rear

quarter glass will not raise. ‘Top Latch

Fail’ will display on instrument pack

after operation

Open circuit in "Top
latch closed" swi tch.

Open circuit in "Top
closed" switch.

Open circuit in "Top
down " switch.

Open circuit in "Top
raised" switch.

Rear quarter glass wi ll lower and hood
will start to unlatch but will only lift
sl igh tly an d rem ain in the l at ch cl aw. Af ter
5 seconds approx., l atch claw will
‘rapi dly’ ret ract pulling top back i nto t he
latc h. ‘Top Latch Fai l’ will displ ay on
instrument pack after operation.

Rear quarter glass will lower and top will
star t to unlat ch but wi ll only l ift sli ghtly
and remain in the latch claw. After 5
seconds approx., l atch claw will ‘rapidly’
ret ract pull ing top bac k in to the lat ch. ‘Top
Latch Fail’ will NOT be displayed on
instrument pack after operation.

‘Top Latch Fai l’ displ aye d on instr ument
pack when the ignition is activated. Rear
quarter glass will lower but top and latch
do n ot f u nc tio n.

Top and rear quarter glass will operate
normal ly, but ‘Top Latch Fai l’ will be
displ ayed on i nstru ment pac k after
opera tion.

‘Top Latch Fai l’ displ aye d on

instrument pack when ignition is

acti vated. Top and lat ch do not

funct ion.

La tch claw wil l rai se bu t top wi ll no t

move. Latch claw retracts aft er 5

seconds of switch op eration. ‘To p

Latch Fail’ will NOT be displayed on

instrument pack after operation.

Top wil l raise and engage in latch claw

followed by a delay b efore the claw

‘rapi dly’ ret ract s. Rear qu arter gl ass

wi ll no t r aise . ‘ To p Lat ch Fail ’

displ ayed on i nstru ment pac k after

opera tion.

‘Top Latch Fai l’ displ aye d on

instrument pack when ignition is

activated. Top and rear quarter glass

do n ot f u nc tio n.

Short circuit in "Top
latch closed" swi tch.

Short circuit in "Top
closed" switch.

Short circuit in "Top
down " switch.

Short circuit in "Top
raised" switch.

Page 8 of 10 Bulletin Number 501-11 Date of issue 9/98 Amended 1/99

Fault Detection Possible Causes

Top Will Not
Rai se

Top Will Not
Lower

Pressing the top
control switch has no
effect on the top
system or r ear quarter
glass.

Pressing the top
control switch has no
effect on the top
system or r ear quarter
glass.

Low battery voltage.
Blown fuse.
Ignition is off or f aulty.
"Top raised" switch is short circuit.
Top control switch faulty.
BPM not receiving signal from top switch.
"Top ready-to-latch"/"Top raised" switch input to BPM is
shorted to ground.
Instrument pack is indicating wrong vehicle speed.
BPM not sending open/close message.
SCP failure

Low battery voltage.
Blown fuse.
Ignition is off or f aulty.
"Top down" switch is short circuit."Top latch closed"
switch is open circuit.
Top control switch faulty.
BPM not receiving signal from top switch.
BPM not sending open/close message.
SCP failure.

Top Will Not
Unlatch

Top Will Not
Latch

Quarter glass lowers
when top control
switch is pressed but
top does not unlatch.

Top raises but does
not latch when it
re ach es th e cl aw.

Low battery voltage.
Blown fuse.
Pump is on manual setting.
Pump/solenoids are disconnected/faulty.
Relay is dislodged/damaged faulty.
"Top latch closed" switch is short circuited.
"Top closed" switch is open circuit.
Instrument pack is indicating wrong vehicle speed.

"Top ready-to-latch"/"Top raised" switch input to BPM is
open circuit.
"Top ready-to-latch" switch is open circuit-Inst. pack
shows ‘Top Latch Fail’.
"Top raised" switch is open circuit - Inst. pack shows
‘Top Latch Fail’.
"Top closed" switch is short circuit - Inst. pack shows
‘Top Latch Fail’.
"Top latch closed" switch is short circuit."Top down"
switch is short circuit.
Latch Control Valve solenoid is stuck active.
Instrument pack is indicating wrong vehicle speed.

Date of issue 9/98 Amended 1/99 Bulletin Number 501-11 Page 9 of 10

Fault Detection Possible Causes

Quarter Glass
Does Not
Rai se

Quarter Glass
Does Not
Lower.

Front
Windows Do
Not
Drop/Raise
Correctly

Quarter glass does
not raise or does not
raise correctly.

Top lowers but
quarter glass does
not.

Front windows do not
drop/rais e for easy
open during top
operation, or not far
enough.

Top is open.
Blown fuse.
"Top latch closed" switch is open circuit - inst. pack
shows ‘Top Latch Fail’.
"Top closed" switch is open circuit - qtrs. rise after 3rd
pre ss.
"Top down" switch is short circuit.
Fault with quarter glass mechanism.
Quarter glass is iced up/stuck to seal.
Ignition is off or f aulty.
Top control switch is faulty.
BPM not receiving signal from control switch.
BPM not sending open/close top signal.

Blown fuse.
Fault with quarter glass mechanism.
Quarter glass is iced up/stuck to seal.
Quarter glass, raise relays are stuck active.

The windows require programming.
Blown fuse.
Electronic fault between SCP and door control modules.
Door modules incorrectly programmed.
Problems with glass/door seals.

Warranty Information:

This bulletin is intended as an aid to diagnosis only.

Page 10 of 10 Bulletin Number 501-11 Date of issue 9/98 Amended 1/99