[xj40] Help identify this part - Fuel Filler Latch Box mechanism

In reply to a message from Don B sent Sat 1 Sep 2012:

Rob,

Sorry, my brain is like boiled squash today. I began to say
that I thought I could explain Bryan’s question about
whether the flap would open with the relay missing and then
proceeded to explain why it should be LOCKED with the relay
missing. I can only assume that the reason the flap would
open is because the plunger stuck in the open position,
unless I am wrong and the solenoid’s no-power default
position is with the rod retracted so the flap can be opened.–
Don B : '93 Vanden Plas : (ex-'88 Sovereign)
Franklin, TN, United States
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In reply to a message from Don B sent Sat 1 Sep 2012:

Don,

Not wishing to be pedantic (but probably am!) I do not
interpret the central locking schematic (circuit diagram) in
the way you do.

I believe, as I theorised in my previous post, that the
filler flap ‘press-to-open’ function can be operated
irrespective of the door lock/unlock condition when the fuel
filler flap relay is not fitted. i.e. that relay is not
necessary to energise the solenoid.

You will notice that the solenoid gets battery voltage
directly from fuse 13 in the left side fuse box on the
Brown/slate wire, not via that relay. I believe that within
the blank white rectangle shown in the schematic inside the
‘filler flap interface’ unit there is a switch which is
activated when the filler flap is pressed down and that puts
the other side of the solenoid coil to ground momentarily on
the Black wire to withdraw the plunger to allow the filler
flap to pop open. There is no continuous drain on the
battery because as the filler flap opens, it disengages the
switch.

The function of that relay is, I believe, as I described in
my earlier post - a) to inhibit the operation of the switch
in the filler flap interface unit so that it cannot operate
when the doors are locked, and b) to ensure that the filler
flap remains closed in the event of an accident which
triggers the inertia switch whilst the ignition key is still
in positions (I) or (II) .

Of course, what we need is someone with an '88 / '89 model
on which the ‘press-to-open’ filler flap is functioning
perfectly (are there any?) to remove the fuel filler flap
relay (if fitted and if they can find it!) to prove that the
‘press-to-open’ still works with the doors locked and
unlocked to prove or disprove my analysis of the system.

In the interests of Jag-lovers worldwide, I’m quite prepared
to have my analysis demolished - providing someone can tell
us how the darn thing really works! :-)–
The original message included these comments:

Bryan is correct that the fuel filler flap is locked when
the passenger doors are locked, and vice versa. There is no
means to operate it independently of the doors.
It is curious that there is no relay in the relay socket.
If the schematic is correct (big if!), the relay is
necessary to energize the solenoid. When you repair the


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Sun 2 Sep 2012:

Hi,

Interesting dialog. Here’s a few thing I know about the
‘‘operational’’ aspect of the latch box since I’ve owned the
vehicle now for about 13 years. (with the understanding
that the latch box is in a functional state)

Vehicle locked - all doors, boot and latch box are locked.
When the fuel filler lid is pressed down the lid is not
released, or won’t spring up to access the fuel cap.

Vehicle unlocked - all doors, boot and latch box are accessible (accessible for the latch box meaning you can
press down on the fuel filler lid and it will release)

The pin/plunger normal state is ‘‘away’’ from the cylinder
(solenoid) via a spring between the plunger collar and the
cylinder base, hence it is always engaging the plunger of
the fuel filler lid.

When the vehicle is unlocked, press down on the fuel filler
lid (it has a plunger on it’s underside) which in turn
applies pressure on a plate, which in turn completes circuit
to energize the solenoid, which ‘‘pulls’’ the plunger inwards
for a second (I would imagine there is a ‘‘timed’’ delay for
‘‘holding’’ the plunger), which in turn allows the fuel filler
lid to pop to the open position via spring loaded hinge.

I too have a theory, or rather a question in regards to the
photos I took of the dismantled latch box. I’m wondering if
the ‘‘mysterious missing relay’’ wasn’t a design change and is
actually part of the apparatus in my pics. Another words the
relay was made part of the fuel filler latch box system. If
you look closely (I know the pics are bad), the solenoid is
connected to a small black box via three wires, which in
turn provides the brown/slate, black and purple wires to the
harness connector. Hmm?

The good folks in charge of manuals/schematics at Jaguar
were probably sick and tired of trying to keep up with
everything and said ‘‘To hell with it!, I’m not doing it
anymore!’’

What do you guys think?

I’m going to send Don and Bryan some additional pics of the
disassembled latch mechanism in a private email due to the
length of time it takes J-L.com to review and post pics.
I’ll will post up the photos later today for everyone.–
The original message included these comments:

You will notice that the solenoid gets battery voltage
directly from fuse 13 in the left side fuse box on the
Brown/slate wire, not via that relay. I believe that within
the blank white rectangle shown in the schematic inside the
‘filler flap interface’ unit there is a switch which is
activated when the filler flap is pressed down and that puts
the other side of the solenoid coil to ground momentarily on
the Black wire to withdraw the plunger to allow the filler
flap to pop open. There is no continuous drain on the
battery because as the filler flap opens, it disengages the
switch.


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
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In reply to a message from Rob Evenson, sent Sun 2 Sep 2012:

Rob,

Where do the Brown/green, Green/purple and Green/orange
wires go in that assembly you have taken out? Those are the
feeds to and from the ‘fuel filler flap relay’ in the
schematics in addition to the Purple/yellow wire connecting
it to the ‘filler flap interface’ unit, so if that relay is
built in to the assembly as you suspect, they should be
there too.–
The original message included these comments:

I too have a theory, or rather a question in regards to the
photos I took of the dismantled latch box. I’m wondering if
the ‘‘mysterious missing relay’’ wasn’t a design change and is
actually part of the apparatus in my pics. Another words the
relay was made part of the fuel filler latch box system. If
you look closely (I know the pics are bad), the solenoid is
connected to a small black box via three wires, which in
turn provides the brown/slate, black and purple wires to the
harness connector. Hmm?


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Rob Evenson, sent Sun 2 Sep 2012:

Rob,

Received your PM with pictures but I’m afraid they are not
clear enough to enable me to identify the wire colours so I
cannot tell which part is which.–
The original message included these comments:

I’m going to send Don and Bryan some additional pics of the
disassembled latch mechanism in a private email due to the
length of time it takes J-L.com to review and post pics.
I’ll will post up the photos later today for everyone.


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Sun 2 Sep 2012:

Hi Rob,

Like Bryan, I’m having difficulty making out sufficient
detail in the photos to make sense of things. According to
the schematic, the filler flap mechanism has an ‘‘interface’’
that is shown only as a rectangular box (no circuit detail).
The relay is shown as a separate component apart from the
interface. I suspect the device you’ve asked about is that
‘‘interface’’ and that if the relay socket is inline with the
power supply to the interface, you will have to install a
relay to return the flap solenoid to proper operation.

I just went out and checked the operation of the flap
locking mechanism on our '93, and it doesn’t appear to have
the ‘‘push to release’’ function you describe in your recent
post. Ours cannot be opened when the doors are locked. I
lifted the flap and operated the door locks several times.
When the doors lock, the solenoid plunger extends to engage
the flap. When the doors unlock, the plunger retracts. I
do note that on my car, when the plunger is extended, it can
be manually pressed back into the solenoid and will remain
in the retracted position, which makes me wonder if my
theory about the solenoid plunger being spring loaded may be
wrong (or perhaps my solenoid is dirty and sticky too).

The above just prompted me to check the schematic for my '93
car, and it’s a different circuit from the '88. The fuel
filler flap uses a bi-directional solenoid that is
controlled by the same dual relay setup as all of the door
locks. The relays are in Relay Module G in the right hand
dash. The central microprocessor tells the relays which
direction to go (it’s a simple flip-flop system in which
each push of the remote control button produces the opposite
effect of the last push). The polarity is reversed to all
the door locks and fuel filler flap solenoid and they all
move in the opposite direction from their last movement. I
wonder if your '89 car was revised from the '88 schematic to
operate more in this fashion? That would explain the third
‘‘ground’’ conductor attached to the side of your solenoid -
typical of solenoids whose electromotive force can be
reversed. Perhaps your theory is correct that your car was
part of a running change and the fuel filler flap relay was
removed as part of the revision.

Don–
The original message included these comments:

Received your PM with pictures but I’m afraid they are not
clear enough to enable me to identify the wire colours so I
cannot tell which part is which.

I’m going to send Don and Bryan some additional pics of the
disassembled latch mechanism in a private email due to the
length of time it takes J-L.com to review and post pics.
I’ll will post up the photos later today for everyone.


Don B : '93 Vanden Plas : (ex-'88 Sovereign)
Franklin, TN, United States
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In reply to a message from Don B sent Sun 2 Sep 2012:

Guys,

Below is the wiring description from the latch connector to
the solenoid/black box assembly:

Brown/slate runs through 1 amp fuse into black box
Purple/yellow runs into black box
Black runs to solenoid (soldered to exterior of solenoid)

Out from the black box:
Red going to solenoid
Black going to solenoid

For your amusement the following is the wiring going to the
White base which is empty (my numbering means nothing other
than the way I visually recorded the wires)

1 Brown
2 White/Pink
3 Black
4 Brown/Yellow (heavy gauge)
5 yellow
6 White/Pink (heavy gauge)

Here’s the layout to the connectors:

(four of the five connector points are used, center empty)
(listed from left, going clockwise)

Brown (1) and White/Pink (2) on one connector point (left)
Brown/Yellow (4)(heavy gauage) on one connector point (top)
Black (3) and Yellow (5) on one connector point (right)
White/Pink (6) (heavy gauge) on one connector point (bottom)

The Yellow (5) and Brown (1) run to the connector via some
sort of testing point

The other wires run into the left harness.–
The original message included these comments:

Like Bryan, I’m having difficulty making out sufficient
detail in the photos to make sense of things. According to
the schematic, the filler flap mechanism has an ‘‘interface’’
that is shown only as a rectangular box (no circuit detail).
The relay is shown as a separate component apart from the
interface. I suspect the device you’ve asked about is that


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
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In reply to a message from Rob Evenson, sent Sun 2 Sep 2012:

Rob,

The Brown/slate, Purple/yellow and Black wires are as drawn
on the schematic for the ‘filler flap interface unit’. The
Red and Black wires are simply downstream of that to the
solenoid but are not separately identified on the schematic.

To find that elusive filler flap relay, you need to follow
the Purple/yellow wire from the interface unit to pin 87 of
the relay’s base - somewhere!

The unoccupied white relay base is most likely the one
designated for the optional ‘auxiliary fuse panel’ if and
when fitted for linking up to a trailer or caravan.

Any time you see a White/pink wire it is for Ignition
Switched Power distribution directly from the Ignition ‘ON’
relay and of course a Black wire is always for ground. A
plain Brown wire is usually an unfused feed directly from
the battery and a Brown/yellow wire is from fuse 15 in one
of the ‘A’ post fuse boxes and probably terminates in a
3-way yellow connector in the left front corner of the
trunk… None of those have anything to do with the central
locking / fuel filler flap system on your car.–
The original message included these comments:

Below is the wiring description from the latch connector to
the solenoid/black box assembly:


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Mon 3 Sep 2012:

Bryan,

I believe you mentioned that your '91 does not have a
locking fuel filler flap. Would that suggest that the
locking flaps were primarily a U.S. spec feature?

The only schematics I have are for the '88 and '93 model
years. On the '93, there is no relay near the filler flap -
the relays are in the Relay Module G in the dash beneath the
glove box (or airbag on '94 cars).

Rob, my thinking is that the most expedient way to diagnose
the fault on your car will be to test for 12V on the
electrical connector for the flap interface. The voltage
should be present either when the doors are locked, when
they are unlocked, or momentarily as the lock mechanisms
are being activated. If your meter registers voltage during
one of those conditions, you don’t have to worry about the
relay; the fault is probably the solenoid.

If, on the other hand, the solenoid measures continuity with
some healthy resistance (tens of ohms to several thousand
ohms), and there is no voltage present at the electrical
connector in any of the three conditions listed above, then
at least one of your problems is the power supply and
possibly the relay(s), wherever they may be. The
gunked-up/frozen plunger rod may have also been part of the
problem.

Let us know what you discover!–
The original message included these comments:

To find that elusive filler flap relay, you need to follow
the Purple/yellow wire from the interface unit to pin 87 of
the relay’s base - somewhere!


Don B : '93 Vanden Plas : (ex-'88 Sovereign)
Franklin, TN, United States
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In reply to a message from Don B sent Mon 3 Sep 2012:

Don,

My '91 does have a locking filler flap.

As far as I am aware there is no ‘press-to-open’ feature on
any XJ40 certainly from '91 MY onwards. The '91 and
subsequent models have a fuel filler flap lock in parallel
with the doors and trunk locks but the filler flap is simply
spring loaded and has to be opened by hooking your finger
under a little lip on the flap to flick it open.

Strangely, the circuit diagrams for the '90 MY do not show
either the ‘press-to-open’ circuitry for the filler flap as
on the '86 - '89 models or the simple filler flap locking
circuit as on the '91 and subsequent models.

The only difference between the '91/'92 cars and the '93/'94
models in that respect is that the central locking,
including the filler flap, is fed from the revised circuitry
and the relevant relay module instead of the old-style cube
relays.–
The original message included these comments:

I believe you mentioned that your '91 does not have a
locking fuel filler flap. Would that suggest that the
locking flaps were primarily a U.S. spec feature?


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Mon 3 Sep 2012:

Bryan,

Thanks for clarifying. My '93 does not have the
‘‘press-to-open’’ feature either, confirming the general
accuracy of your schematics. I can’t remember if my '89 had
the press-to-open feature or not.–
The original message included these comments:

My '91 does have a locking filler flap.
As far as I am aware there is no ‘press-to-open’ feature on
any XJ40 certainly from '91 MY onwards. The '91 and
subsequent models have a fuel filler flap lock in parallel
with the doors and trunk locks but the filler flap is simply
spring loaded and has to be opened by hooking your finger
under a little lip on the flap to flick it open.
Strangely, the circuit diagrams for the '90 MY do not show
either the ‘press-to-open’ circuitry for the filler flap as
on the '86 - '89 models or the simple filler flap locking
circuit as on the '91 and subsequent models.


Don B : '93 Vanden Plas : (ex-'88 Sovereign)
Franklin, TN, United States
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In reply to a message from Don B sent Mon 3 Sep 2012:

Here’s an update. Unfortunately my friend is out of town so
I was left to my own devices (that can become diabolical if
left unattended).

I went to the store and purchased two 6v batteries and
hooked them up to produce 12V. Here’s what I did:

Applied 12v directly to solenoid unit and it worked. I cut
the red and black wires so I could apply voltage directly to
the solenoid and I wanted to be able to read the output from
the black box.

Applied power to the pins on the connector to brown/slate
and black and read power between the inline fuse on
brown/slate (in front of the black box) and the black wire
from the connector that is soldered to the solenoid, got
12v.

With power still applied as prior, meter set on ohms and
connected to red and black out of black box (these are the
wires that go to the solenoid), depressed pressure plate for
a second and the ohms jumped from 0 to 19.7, but it remained
at that level for 8-10 seconds before it dropped to zero.
Applied presure again and it went to 19.5, then dropped
immediatley. Applied pressure again and read 19.6, but it
stayed at that level for 10 seconds or longer so I dropped
the power to the connector and it droped to zero. Did this
exercise at least a dozen times and had varied results, no
consistent behaviour.

I’m going to pry open the black box, I think this may be a
one way ticket, but it’s not working anyway so what the
heck.

By the way, I connected the latch relay to the harness the
other day and depressed the pressure plate and guess what…
It blew fuse 13 on the left A post. What to think??? Also,
when I did that test, it did not activate the solenoid, so
the black box is still suspect.

Keep you posted.–
The original message included these comments:

Let us know what you discover!


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
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In reply to a message from Rob Evenson, sent Tue 4 Sep 2012:

Rob,

By ‘‘latch relay’’ do you mean the filler flap relay??

If so, I thought throughout this thread you had claimed that
you couldn’t find that relay?

Blowing fuse #13 in the left fuse box in the manner you
describe is a little puzzling. That fuse I believe is 15
Amp. If something in the filler flap interface unit grounded
the Brown/slate wire which puts battery power on to the
unit, why would it blow a 15 Amp fuse but not the 1 Amp
in-line fuse in that feed to the unit???–
The original message included these comments:

By the way, I connected the latch relay to the harness the
other day and depressed the pressure plate and guess what…
It blew fuse 13 on the left A post. What to think??? Also,
when I did that test, it did not activate the solenoid, so
the black box is still suspect.


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Tue 4 Sep 2012:

Bryan,

I meant the latch mechanism (connector, inline fuse, black
box and solenoid).

Sorry for the misque.

I opened the black box halfway and am staring at a circiut
board with transistors and the four wires to it, not sure
what to look for. I have to still take off the other half
yet to see the actual solder connections. The black box or
casing is indeed some sort of epoxy material, real pain to
get it apart. Not real sure I can get the circuit board out
of the other half without cutting it apart in pieces.

One bit of news, the board was manufactured in UK by Pektron
LTD, out of Derby. Alfreton Rd to be exact, still in
business. It was manufactured in 1986.

Keep you posted–
The original message included these comments:

By ‘‘latch relay’’ do you mean the filler flap relay??
Bryan N, '91 Sovereign 4.0 L, RHD


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
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In reply to a message from Rob Evenson, sent Tue 4 Sep 2012:

Rob,

A few thoughts/questions:

  1. The presence of transistors or other electronic
    components in the black box raises questions. Why are they
    there? One possibility is to reduce the voltage to the
    solenoid coil or coils. One or more of the components that
    look like transistors could be voltage regulators. You
    might try testing the solenoid with just 6V to see if it
    operates.

Another possibility is that the electronic circuit is a
switch that isolates the control circuit from the power
circuit like a relay, but using transistor switching.

It may be the switching circuit associated with the pressure
plate you reference (my '93 does not have such a plate).

It might also be some sort of logic circuit that causes the
solenoid to operate in opposite directions with each
successive application of voltage.

  1. I gather that you applied 12V directly to the red and
    black wires that you cut on the solenoid and that caused the
    solenoid to react either by extending the plunger or
    retracting the plunger. When you removed the 12V power, did
    the plunger move again under spring power? If the plunger
    remained where it was, did reversing the 12V polarity cause
    it to change positions? You might try this test with just
    6V first.

  2. Does applying power to the wire attached to the side of
    the solenoid, plus either the red or black wire on the end
    of the solenoid cause it to operate? If so, does connecting
    power to the other end wire cause the plunger to operate in
    the opposite direction? Try the test with 6V first, and if
    nothing happens, try 12V.

  3. My suggestion to use an ohmmeter was to measure the
    continuity of the solenoid coil to see if it had been broken
    or shorted. I was not suggesting that you measure the
    resistance or impedance of the output of the black box. I
    think we’re more concerned with the voltage output of the
    black box. If you can confirm that the solenoid will
    operate in both directions, we don’t need to worry about its
    resistance (ohms). If it works in both directions, you’ll
    know the coil or coils is/are good.

  4. Not knowing how you connected the flap mechanism to the
    harness, it’s difficult to know what may have caused fuse 13
    to blow other than a direct short of battery power to ground
    somewhere in your hookup. I assume you must have connected
    to the flap solenoid after the 1A fuse or it should have
    blown as Bryan observed.–
    The original message included these comments:

Applied 12v directly to solenoid unit and it worked. I cut
the red and black wires so I could apply voltage directly to
the solenoid and I wanted to be able to read the output from
the black box.
Applied power to the pins on the connector to brown/slate
and black and read power between the inline fuse on
brown/slate (in front of the black box) and the black wire
from the connector that is soldered to the solenoid, got
12v.
With power still applied as prior, meter set on ohms and
connected to red and black out of black box (these are the


Don B : '93 Vanden Plas : (ex-'88 Sovereign)
Franklin, TN, United States
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In reply to a message from Don B sent Tue 4 Sep 2012:

Guys,

I applied 6v to the solenoid and it did work, in fact it was
a little smoother in operation. From what I can tell the
solenoid is only activated when power is applied to retract
the piston. When the power is removed the piston springs
back out to it’s ‘‘normal’’ position.

The thought occurred to me this evening in regards to the
latching mechanism and the car security. I’m beginning to
think that instead of power being applied to the solenoid
when the vehicle central locking system is activated, the
power supply is interrupted instead, thus the pressure pad
is negated while the central locking system is engaged.
This would probably hold true if the inertia switch is
engaged as well. I believe the only function of the solenoid
is to retract the piston momentarily when the pressure plate
is pressed.

In regards to do an ohm reading on the black box, I couldn’t
get any other reading from it. I tried to read DC and I used
the continuity setting as well. The ohm setting is the only
setting that registered a response that was measurable. It
seamed to me that the inconsistent behavior of the readings
indicates a problem with the black box, actually we need to
call it the latch mechanism circuit board for now on. I
have most of the epoxy off and got tired of the task a few
moments ago, have three xacto knife wounds, one requiring
several band-aids. I’m going to spend a few more hours on it
tomorrow am, I think there is a poor soldering connection on
the purple/yellow wire.

I connected the latch mechanism connector to the wire
harness connector (not sure how else you thought I would do
that), then used a small screwdriver blade to complete the
circuit for the pressure plate. It might be coincidental.

post to you later,–
The original message included these comments:

might try testing the solenoid with just 6V to see if it
4. My suggestion to use an ohmmeter was to measure the
5. Not knowing how you connected the flap mechanism to the


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Rob Evenson, sent Tue 4 Sep 2012:

Well if the solenoid retracts, you’re in luck. The issues I
had with both of my 88s was that the post on the lid had
poked a hole in the dense foam rubber that covers the
pressure switch, so pushing down on the lid never activated
the switch. (I think the epoxy-encased electronics is a
time delay circuit that holds the solenoid energized long
enough to allow the lid to open past the latching pin.) I
was able to turn the dense foam rubber end-for-end and it
worked as it should. You may be able to do the same, but
you may have to replace the rubber entirely with a harder
rubber.
Sorry to hear about the lacerations, but a little blood
helps create a sense of accomplishment, I suppose.–
The original message included these comments:

I applied 6v to the solenoid and it did work, in fact it was
a little smoother in operation. From what I can tell the
solenoid is only activated when power is applied to retract
the piston. When the power is removed the piston springs
back out to it’s ‘‘normal’’ position.
This would probably hold true if the inertia switch is
engaged as well. I believe the only function of the solenoid
is to retract the piston momentarily when the pressure plate
is pressed.


Pete Peterson 70E(193K) 88XJ40s(270K & 256K) 94XJ40 (122K)
Severna Park, Maryland, United States
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In reply to a message from Jaguarpete sent Thu 6 Sep 2012:

Pete,

Thanks for the sympathy note, unfortunately I couldn’t get
the darn thing working. I think you were the fortunate one
by only have to deal with the foam rubber pad.

I agree with your assessment of the use of the circuit
board, aside from providing a delay, I think it may also
reduce power supplied to the solenoid.

I have officially thrown in the towel on repairing the
circuit board; could not get it to work. I did tear off the
epoxy enclosure:

http://www.jag-lovers.org/v.htm?1347031229

The only thing I have at this point is theory. When
dismantling the epoxy there was a significant different in
the composition of the material from one side to the other
(see pics) the bottom half of the epoxy enclosure cube came
off easily, this is the side that would have been ‘‘away’’ for
the exterior of the vehicle. The other half, closest to the
exterior was incredibly difficult to peel away. In fact I
had to pick it apart in pieces to expose what you see in the
pics.

My theory is in my scenario, the circuitry was ‘‘baked’’ to a
point of deterioration. As referenced in the prior posts in
this topic, power was present, except coming out of the
circuit board. So I call this one to a close and have re-
installed the fuel tank with latch box, less the latch
mechanism with circuitry.

Thanks to all for your input, advice and patience.–
The original message included these comments:

Well if the solenoid retracts, you’re in luck. The issues I
had with both of my 88s was that the post on the lid had


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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Rob. Looking at the photos slide 8 top right looks to me to be a voltage
regulator.
I cannot tell what the output should be from the photo but they are used to
provide a certain power output from a range of inputs.
This is to give stabillity to the components downstream as far as I know. I
do stand to be corrected as I am only a humble noob when it comes to these
things.
Regards Robin O’Connor
'92 XJ40 4.0 Ltr
Auckland NZ----- Original Message -----
From: “Rob Evenson,” evenson.rob@gmail.com
To: xj40@jag-lovers.org
Sent: Saturday, September 08, 2012 6:39 AM
Subject: Re: [xj40] Help identify this part - Fuel Filler Latch Box
mechanism

In reply to a message from Jaguarpete sent Thu 6 Sep 2012:

Pete,

Thanks for the sympathy note, unfortunately I couldn’t get
the darn thing working. I think you were the fortunate one
by only have to deal with the foam rubber pad.

I agree with your assessment of the use of the circuit
board, aside from providing a delay, I think it may also
reduce power supplied to the solenoid.

I have officially thrown in the towel on repairing the
circuit board; could not get it to work. I did tear off the
epoxy enclosure:

http://www.jag-lovers.org/v.htm?1347031229

The only thing I have at this point is theory. When
dismantling the epoxy there was a significant different in
the composition of the material from one side to the other
(see pics) the bottom half of the epoxy enclosure cube came
off easily, this is the side that would have been ‘‘away’’ for
the exterior of the vehicle. The other half, closest to the
exterior was incredibly difficult to peel away. In fact I
had to pick it apart in pieces to expose what you see in the
pics.

My theory is in my scenario, the circuitry was ‘‘baked’’ to a
point of deterioration. As referenced in the prior posts in
this topic, power was present, except coming out of the
circuit board. So I call this one to a close and have re-
installed the fuel tank with latch box, less the latch
mechanism with circuitry.

Thanks to all for your input, advice and patience.

The original message included these comments:

Well if the solenoid retracts, you’re in luck. The issues I
had with both of my 88s was that the post on the lid had


Rob Evenson, '89 XJ40/XJ6
Mobile, AL, 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 !

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 !

This site is amazing with the info and responses! I would be lost with out the help from fellow jag owners! Thanks