Jaguar XJ-S. Service manual — part 157

623

Of course, the connector on your car may be different than the author’s ’83, so you might need to confirm those
connections with a VOM. With the ignition switch turned to ACC, the W LG post should register 12V with the wiper
switch in fast mode only. The B LG post should register 12V with the switch in slow mode only. The K LG should
register 12V with the switch in intermittent/flick or off modes only. Turn the ignition off, and using ohmeter or
continuity mode, you should get continuity between O LG and B LG posts in intermittent/flick and off modes only.
Obviously, the ground terminal should register continuity to ground.

Also on the author’s ’83, there is a harness that starts with the plug that connects to this socket on the panel and plugs
into the motor itself. At the motor end, it becomes evident that the wire colors in this harness do not correspond to the
wiring schematics -- they are solid-color wires. And the plug is enclosed so you can’t tell which wire goes to which
connector by looking. It’s not too difficult to determine which wire is which using a VOM, though:

Yellow

=

W

LG

Green

=

Ground

Brown

=

B

LG

Red

=

O

LG

White

=

K

LG

WINDSHIELD WIPER MOTOR DURABILITY: A design problem with the Lucas wiper motor is that the drive
gears at the wiper arm shafts are plastic. Wear is a reported problem, and can be aggravated by operating the wipers on
a dry windshield. It is suggested that the XJ-S owner use Rain-X or similar product on the windshield on a regular
basis. This will make the water run off so the wipers need not be used as often, and it will also make the surface of the
glass more slippery, so the wipers move more easily.

WINDSHIELD WIPER PARKING: If your Lucas reverse-park wipers don’t park, you may be tempted to start tearing
the wiper motor apart to work on the parking contacts -- but you would be forgetting that this is Lucas you’re dealing
with. As Mark Roberts found out, the problem is every bit as likely to be within the stalk switch. “Because the wipers
would park in intermittent mode, I was skeptical about the problem being with the parking micro switch, but checked it
anyway. Micro switch was fine. The problem was traced down to the stalk switch. In the off position, pins 5 & 6
(ULG & BLG respectively) are supposed to be shorted together, to provide a ground path for the motor. They are also
supposed to be shorted when in intermittent mode for the same reason. On my switch, 5 & 6 were shorted in
intermittent mode, but open in the off position...no ground, no work.”

Dan Jensen provides more info: “There is a simple in-car test to determine if the switch is the problem. After turning
the wipers off and having them stop midstroke, simply push down slightly on the stalk toward the intermittent position
(but not the "locked" intermittent position). If the wipers park, it is the switch.”

Jensen had this same problem on three different Jaguars! “Unfortunately, after disassembly of the switch in my '81, I
could not come up with a successful way to repair it. The cause seems to be slow deformation over time of the plastic
slide that supports the copper contacts in the switch. The slide is held against the stalk by a rather stiff spring that
apparently leads to an inexorable depression in the plastic slide contact surface. At ~$100-125/switch, I will probably
just live with the problem.”

Tom Amlie says a new switch might not even fix it. “Ordered a new switch for $82. It was defective straight out of a
sealed green box with the leaper on it. Took the old one apart. It has a flat plastic card with indentations in it. In the
indentations are little pieces of copper. As the card moves in and out, the little pieces of copper are supposed to make
and break connections as necessary. Trouble is, they are not anchored in any way and fall out. A few drops of crazy
glue on the copper pieces and glued the thing together. Worked fine. This was my first experience with the "Prince of
Darkness". I think you are too easy on Lucas in your book.”

This author had the same problem and managed to fix it by disassembling the switch. Reassembly requires some
ingenuity. A 2-1/8” length of 1/2” aluminum angle and two 1-1/2” #6 screws works well. Cut some plastic away on

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the back side of the switch, then lay the angle against it and insert the screws through holes in it and into the threaded
mounting holes in the switch housing. The screws will protrude through the front, where you can use the ends to mount
the switch back in the column with a couple of nuts and lock washers. The metal angle will help prevent the plastic
housing from deforming and allowing the contact problems described above.

WINDSHIELD WIPER ARM MOUNT: The wiper arms are mounted on the shafts with a taper fit, held tight with a
nut that is hidden by a plastic cover. The plastic cover can be simply swung up to reveal the nut, and if desired can then
be pulled directly off; it just snaps into place. The nut really should have a washer under it; if not, the 8mm wavy
spring washers described on page 26 will work well.

The base portion of the arm is made of aluminum, and a slight growth or wallowing of the tapered hole is an occasional
problem. Contrary to expectations, this cannot be dealt with by merely tightening the nut further or stacking washers.
The nut bottoms on a shoulder above the taper, and the arm remains loose.

There is a second result of this problem. When the nut pushes the arm too far down onto the taper, the bottom of the
arm can pinch the rubber shield against the mount bushing and bind up the movement of the wiper. These motors have
enough trouble moving as is, they don’t need binding on top of it. After installing the arms and tightening down the
nuts, grab the rubber shield between two fingers and try to turn it on the shaft. If you cannot turn it, it’s probably
binding.

These problems can be easily corrected. Cut a 1/4” wide arc from thin sheet aluminum (beer can for minor problems,
old real estate signs if more thickness is needed) and roll it into a conical shim. Installed between the shaft and the arm,
it will provide a tight fit.

MOTOR MAGNET REINSTALLATION: As mentioned on page 617, the permanent magnets have been known to
come loose inside the motor casing. If the ceramic magnets haven’t shattered, it’s pretty easy to clean them up and
reinstall them with JB Weld -- but you need to know where they go. Since the author has done this, the following
guidelines should serve for anyone who owns a similar Lucas reverse-park motor:

On the author’s motor, the case is a simple metal cylinder 2-7/8” long, 3” in diameter, and open on both ends. There is
a dovetail joint where the metal was stitched together to make a cylinder, but there’s no telling if that joint is located in
the same place on all motors. There is a V notch at one end of the dovetail joint, and there are two small rectangular
notches near the dovetail joint -- but none of these notches have any apparent purpose, so again there’s no telling if
they’re in the same place on all motors.

The one thing that is reliable is a small alignment mark. It’s a straight line about 1/4” long, near the gearbox end of the
case. It is meant to be aligned with a triangular alignment mark on the gearbox housing. Hence, the magnets need to be
reinstalled properly relative to this mark.

The magnets should be installed 5/8” from the end plate end of the case. This results in them being 7/8” from the
gearbox end of the case.

The magnets should be equally spaced from each other, and equally spaced on either side of the alignment mark.

Hold a magnet with the concave side -- the side that faces the rotor -- near the side of a compass. If the S point of the
compass needle turns and points towards the magnet, set that magnet down and pick up the other one. You want the
magnet on which the concave side attracts the N point of a compass needle.

Hold the casing in such a way that the gearbox end is up and you’re looking at the alignment mark. The magnet you’re
holding should be installed on the side of the case to your right.

With a magnet in place in the case, you could remove the magnet, rotate it front-to-back, and put it back in in the same
place and it wouldn’t look any different. Relax, it also won’t make any difference. The important thing is to have the
correct magnet on the correct side of the case.

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PITIFUL WINDSHIELD WIPER OPERATION: The performance of the early/mid-80’s Lucas wipers is really sorry.
They behave as though they are “dragging themselves into the grave.” And switching from slow to fast speed makes
so little difference you’d hardly notice it. This problem is similar to that causing the slow electric windows (see page
602), so a similar solution is recommended: a relay scheme should be incorporated to provide solid 12V power directly
to the wiper motor without having to go through the stalk switch and the skinny wiring to get there.

Figure 35 is a schematic for installing up to three relays in the reverse-park Lucas wiper system. It should be noted
that an owner can choose to install any one, two, or all three of these relays to improve his wiper performance. To
explain: due to the way the control system works, both the 12V power and the ground connections go through the stalk
switch and the wiring in between. It is probable that there are just as many volts lost in the ground wiring as in the
power wiring. To improve any individual mode, one could install a relay to provide solid 12V power or one could
install a relay to provide a solid ground connection, but for truly optimum performance one should install both. In
Figure 35, Relay 1 provides one good connection for all modes; Relay 2 provides the other good connection for fast
speed mode; and Relay 3 provides the other good connection for slow speed, intermittent, flick, and park modes.

Figure 35 - Windshield Wiper Relays

Installation of all three relays should also make the stalk switch last longer, since it will no longer be carrying the heavy
current.

Relay 1 and Relay 3 both must be SPDT relays (with 87a terminals -- see page 561).

Note that the second set of contacts in Relay 2 is really part of the Relay 3 scheme; if Relay 3 is not being installed, a
SPST relay (common automotive relay) can be used for Relay 2.

If Relay 3 is being installed, two separate automotive relays with their coils wired together can be used for Relay 2
rather than trying to find a suitable double-pole relay with 20A contacts.

If Relay 3 is the only scheme being implemented, it will require two relays -- the one labelled Relay 3 and a SPDT
wired as the right half of Relay 2 in the schematic, with the coil connected to the Y wire without breaking it.

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Figure 35 shows a 12V power supply connected through a 20A fuse for each relay, but this is mainly for clarity and
simplicity of illustration. In practice, a single 12V power supply should be run for all relays, and a single 20A fuse
should be used; only one relay will be drawing current at any time. Note that the label on the fusebox may indicate a
35A fuse is needed for the wipers, but that reflects the difference between UK and US fuse standards (see page 584). If
you are using UK-rated fuses, you should use a 35A.

In application, the power for the author’s installation came from one of the main posts on the firewall, and a wire was
run through one of the bolt holes originally used to mount the heater valve (which had been replaced and relocated --
see page 493). A couple of layers of heat-shrink tubing were applied around the wire at that point to protect it from
rubbing inside the threaded hole. The ground wire was attached using a bolt threaded into the other mounting hole for
the heater valve. Note that later cars have plastic nuts pressed into holes to mount the heater valve instead of the
welded-on nuts on the ’83, so the plastic nuts should be removed and a grommet and a bolt and nut should be used for
the power and ground wires instead. If you still have the original heater valve in place, you could just drill new holes --
but, seriously, it would probably be a far better idea to spend the ten bucks on a new heater valve.

The fuse I used is a modern plastic type, and was located in the engine compartment to make it easy to replace if
necessary. The relays themselves were installed within the wiper compartment, but far to the right and high up under
the bodywork to protect them from rain.

There is a cable, DAC2644, that plugs into the bulkhead connector within the wiper compartment and into the motor
itself -- see page 622. As a result, you can cut this cable and splice in the wiring to connect up these relays without
fiddling with either the wiper motor itself or the wiring behind the dash; the only reason to open the door on the car is to
turn the wipers on to test them out! The most challenging part of the job is getting the wiper grille out and back in
when done.

Note that Relay 1 and Relay 3 will be energized when the wipers are off. This is not really a concern, however; relays
are designed for continuous operation, the coils take very little power, and the relays will be deenergized when the
ignition key is turned off.

Relay 3 only helps the modes where the wipers are supposed to be operating slowly. This may sound silly -- if you
want more speed, just switch to fast speed! -- but in fact getting the slow speeds to operate smoothly and powerfully
without the typical pitiful straining could be considered worthwhile. There’s no danger of the motor running too fast;
slow speed is provided by the design of the motor, so although it will be faster than the dragging OEM setup, it will still
be slower than fast mode.

In fact, Relay 3 may be the most important scheme to install because it’s involved in the wipers parking. Park is one of
the slow modes that isn’t helped with the high speed relays, so when the glass gets dry putting it in park may cause
them to drag or even stop altogether without making it back to park position. This is really bad, because the power is
left on in the motor.

If you install all three relays as illustrated, Fuse #9 in the main fusebox will no longer carry any serious current; it will
be powering only the three or four relays you have installed and the delay unit. You can remove the 20A or 35A fuse
and install a 3A fuse.

Windshield Wipers -- Electrolux

Beginning around 1987, the XJ-S was fitted with an Electrolux motor. This unit has metal gears at the wiper arm
shafts, as opposed to the plastic gears on the Lucas. There are few reports of problems, so it must be a fairly reliable
unit. Stefan Schulz says “The parts guy at my local Jag dealer says that it is not a drop-in replacement for the Lucas
one.”

If the Electrolux motor drags, adding a relay scheme may be helpful as it is with Lucas motors. However, somewhere
in the late 80’s or early 90’s Jaguar (or Ford) realized the error of their ways and began providing relay schemes for
heavy loads in their cars from the factory. Which happened first, and whether there’s any such thing as a car with
Electrolux wipers without relays, I don’t know. If your Electrolux wipers drag, that might be an indication.