Jaguar XJ-S. Service manual — part 167

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cruise control switch on the console (underneath the driver-side console ashtray). It will require that you remove the
console veneer entirely.

“I found the fuse wiretied closely to a bundle, as well as electric taped over the fuse housing to another line (dunno why
- I eliminated the tape when I was in there). I found a 2A fuse in there, but the manual calls for a 1A - both of which
are odd, given that the stock Jaguar stereo had a 10A fuse on it -- fused to that same power input as the inline fuse is on
(as versus the ignition/accessory input which tells the stereo to wake up). I checked with the local Jaguar dealership
and he said there shouldn't be a problem for that line to carry 10A, so I switched the inline fuse to a 10A and the stereo
works fine.”

Actually, the situation could use a little more explanation. The Haynes manual and the ROM seem to talk only of a
“radio” and otherwise provide little info on wiring of the stereo system, but with almost any system there are actually
two separate power supplies: a switched and an unswitched. The unswitched is connected to the battery at all times
while the switched turns on and off with the ignition key. In the old days when things were simple, the unswitched line
drew only a tiny amount of power, since all it did was maintain the settings on the tuner presets and the like; the
switched line, which powered the amplifier itself, the tape drive mechanism, and anything else you didn’t want on when
the car was off, drew the relatively heavy current. Hence, the switched line would be fitted with a 10A fuse or some
such, while the unswitched line would get only a 1A.

Then the serious autosound buffs came up with the idea of installing huge capacitors in the power supply to a stereo
system. These “stiffener capacitors” can range from 0.25 farad (already larger than most any other capacitor used
anywhere by several orders of magnitude) up to 1.5 farad; the rule of thumb is 0.001 farad for each watt of amplifier
power. These capacitors are typically about the size and shape of a 12-oz. beer can, and some stereo buffs connect up
entire banks of them! Their purpose is to maintain a rock-steady voltage supply to the stereo when the stereo itself calls
for a sudden surge of power, such as when a heavy bass note is hit.

The problem is that such capacitors cannot be on a switched line. In fact, installing them in a car requires some care in
pre-charging through a resistor before connecting, or something will get fried. Once installed, they must remain in
continuous connection with the battery at all times, and disconnecting the battery for servicing the car requires
discharging and recharging through the same resistor when reconnecting. If installed on the switched circuit, the first
time you hit the ignition key the contacts within the ignition switch would weld themselves into a handsome little glob.

As a result of these developments, the modern stereo systems have changed the standards. They still require a switched
and an unswitched power supply, but in order to take advantage of stiffener capacitors and other power supply
upgrades, the heavy current is taken from the unswitched line. The switched power supply now becomes merely a
“signal” that the ignition is on, and therefore draws almost no power.

Obviously, if you remove an original deck that drew its amplifier power through the switched line and install a newer
deck that draws its amplifier power through the unswitched line, the first thing that’s gonna happen is you’re gonna
blow the tiny fuse that was originally intended only to maintain station presets. Straw’s dealer is correct, almost any
circuit in the car will handle a 10A fuse without trouble, so you can merely replace the 1A inline fuse with a 10A to
make your new deck work. On the other hand, you might opt to run a new heavy-duty power supply wire from one of
the two main terminals on the firewall directly to your new deck to make sure it’s not starved for amps when you’re
rockin’ out.

CD CHANGER ADDITION: David Brown sends this info on installation of a CD changer in the boot: “I believe all
post-’88 cars are pre-wired. Depending on what year you have, a 7-pin DIN socket (that’s what we call it in the UK
anyhow) will be found in different places in the boot (trunk).

“... a Clarion changer unit will plug straight in and you’re all set.

“For a Philips or Alpine unit, you have to disassemble the plug on your CD changer and rewire a couple of pins around.
Basically you can control the unit as it is currently wired, but you would hear nothing. The head unit expects the
sound signals to be traveling down some otherwise unused pins. Simple experimentation shows what they are.

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“On my Philips unit, I had a DIN plug which carried the instructional/power signals and had separate phono/tulip plugs
which carried the sound. I patched those sound signals back into the DIN plug at the 11 and 1 o’clock positions. You
could find out which pins should carry the signal by half connecting the CD changer to the cars socket, such that the
changer works but you can still see the pins. Then dab each pin with a phono cable until you hear the music come
through. Then you’ll know which DIN pins are expected to carry the sound signal.”

If you have this connector, the stock Jaguar stereo includes controls to operate these CD changers remotely.

CD CHANGER ADDITION -- FM MODULATOR TYPE: If you have an earlier car that isn’t pre-wired for a CD
changer, you can still add one by getting the type that splices into the FM antenna. This is convenient, since the
antenna on the XJ-S is in the trunk. Such systems inherently lack some of the high frequency response of a directly-
wired CD player, but it’d be the rare individual indeed who could tell the difference.

Bill MacDonald says, “All CD changers have a gain control for the output to the FM modulator. The little silver box
that has the antenna wires and data and power connections contains the modulator on older Sonys. New models of all
brands seem to be building the modulator on the circuit board right inside of the changer. You can adjust the gain
either by an adjustment that is made for you to adjust the gain on the box or open it up and you can adjust a universal
gain or a single left and right gain. You are supposed to match the FM volume equal to the CD volume, but it’s your
choice.

“You can also adjust the frequency deviation and offset; a lot of radios are not tuned exactly as they should be and
sound scratchy or "s" words sound horrible. Be very careful and use plastic adjustment tools and I only recommend
this if you have patience and dexterity because you can also detune the carrier and pull it out of PLL stereo mode. But
if you sit in the middle of a quiet car with no noise around you and relax and adjust the modulator with your ears you
can tune it in to sound a lot better than what it was factory adjusted to.”

HEAVY-DUTY POWER: If you’re installing a whopper of a sound system, you might consider replacing the Lucas
alternator with a GM alternator as described beginning on page 573. This would permit installation of a reasonably-
priced 140-amp alternator.

If 140 amps isn’t enough, you may want to note the idea of replacing the air pump with a GM alternator discussed
beginning on page 577. While the intention there was to eliminate the original Lucas alternator, there’s no reason this
same modification couldn’t be used to fit the XJ-S with two alternators. Connecting two alternators to a single
electrical system is reportedly unwise, but providing two entirely separate electrical systems is reportedly a fairly
common exercise in the world of high-power sound.

Antenna

TYPES: In general, two types of antenna (“aerial” in the Jaguar parts books!) were used in the XJ-S. Up through VIN
123280, a Merlin antenna DAC3542 was used; this is a remote unit in which the drive assembly is buried under a panel
in the right side of the trunk, and a cable housing connects it to the mast. From VIN 123281 on, a Hirschmann antenna
DAC3579 was used; this has a black plastic rectangular housing. It is not remote, the drive assembly is right where the
antenna is.

Richard Mansell says “I have a feeling the XJ40 uses the same electric aerial as the later XJ-S’s.” Actually, not quite
right; the XJ40 uses a Hirschmann antenna DBC5101, but this unit looks almost exactly the same except for the
electrical connection. It even uses the same replacement mast.

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ANTENNA VS. SPOILER: Richard Mansell: “When you have a boot spoiler it’s a bit of a problem as the mast goes
through a small hole in the spoiler!” John Goodman explains: “On the boot spoiler equipped cars there is an additional
relay wired into the boot light switch. The idea is that when the aerial is extended, radio and ignition on, lifting the lid
very slightly causes the boot light to come on and the aerial to retract (after the stupid 4 second delay).”

ANTENNA MAST LUBRICATION: Michael Minglin says, “Porsche dealers sell a small foil packet with an oil
soaked swab inside. This is to lubricate the antenna shaft.” Hal Rogers (see page 709) adds, “Jaguar also sells a similar
lubricating pack as well. A number of Jaguar specialists (like myself) carry it. It is very inexpensive.” Considering the
wealth of information listed below on repairing the antenna, maybe this lubrication is a good idea.

MERLIN ANTENNA DRIVE WIRE REPLACEMENT: Steve Leamy says: “Some models use a plastic drive wire
instead of metal; you can repair these with weed eater line but you have to remove the motor base and ant to service it.”

Dan Jensen tried using 0.080” grass cutter line, and it didn’t work. “The main problem was it was stiff enough when
coiled into the tight end of the coil guide that it popped out between the guides and jammed. I think having a material
that (a) is reasonably flexible, (b) is tough enough to stand repeated uncoiling and coiling, and (c) has an o.d. near 0.125
are all important. I see no reason why grass cutter string would not work, but the o.d. needs to be close to 0.125 in.
Note that the original extend/retract cable has a small hole in the center, i.e., it is very thick-walled tubing vs. flexible
rod.”

“I also tried PTFE (Teflon), but it quickly failed due to the repeated flexing. Ultimately, I used 0.125 inch flexible
polyethylene rod purchased from a local valve supply company. This has worked without problems.”

MERLIN ANTENNA MAST REPLACEMENT: Hal Rogers of H. D. Rogers & Sons (page 709): “It does not have a
replaceable mast, never did.”

ANTENNA CLUTCH ADJUSTMENT: Steve Leamy sends instructions on adjusting the drive clutch, apparently on
the Hirschmann antennas but perhaps applicable to all: “This repair covers ant that just won’t quite make it up or down
and still makes a clicking noise before stopping.

“You want to get to the side of the unit that looks like a cup and has a screw in the middle of it. Remove the screw and
the cover and you will have now exposed the clutch drive for the ant. On the shaft in center you will find a locking nut
which you will now back off 1 or 2 turns, now grip the metal clutch and tighten 1/2 turn. Retighten locking nut and
prop unit up so you can test it. Turn key on and radio and ant will raise in 15 to 20 seconds, once ant reaches full height
you should hear 3 bumps and ant motor should shut off. Turn key off and ant should go down completely and 3 bumps
and motor will cut off. If ant still does not go full up or down adjust clutch in quarter turns until a full stroke is attained.

“On 88 and above XJ’s I have found three different manufacturers of ant in the cars I have serviced the but all of them
use some type of clutch system and can be fixed by resetting of the tension on it.”

HIRSCHMANN ANTENNA MAST REPLACEMENT: While the Merlin mast is driven via a plastic wire, the
Hirschmann mast is driven by a plastic strip with a row of teeth down one side. These teeth engage a drive sprocket
inside the unit.

A repair kit is available for Hirschmann antennas, including the mast and the plastic gear rack. The Jaguar part number
is DBC2200. According to Hal Rogers, “The mast is the same for some German cars.”

John Goodman suggests: “Replace the mast the easy way!!!

“1. Undo mast securing nut on top of wing/fender(leave unit intact in car).

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“2. Get helper to switch radio on, while you pull up on the mast, the motor will extend the mast right out of the car
complete with nylon cable.

“3. Put new mast into hole, get helper to turn radio off, motor will pull new mast into hole, tighten securing nut.”

HIRSCHMANN ANTENNA -- BROKEN DRIVE COG: Samuel J. Louw shares his experience on his ’89 XJ-S with
the Hirschmann antenna: “I tested it with the cover off and saw that the motor was driving the gear, but that the second
gear driving the antenna was not turning. I took the two gears apart and found the plastic pin transferring the driving
force from the drive gear via the internal spring to the antenna gear broken off. The first glue attempt was unsuccessful,
but on second attempt I enlarged the hole, which the plastic pin already has, a bit and fitted a small self-tapping screw,
together with some steel epoxy. Antenna is working fine now. Glue and screw just needs to be flush with the gears.”

HIRSCHMANN -- OTHER FAILURES: Most automatic antennas have a motor with a worm gear on the shaft that
drives a wheel connected to the spool that winds the mast up and down. The Hirschmann has a difference: instead of
the worm gear being on the motor shaft, it’s alongside the motor and there is a tiny toothed belt driving it. So, if the
thing isn’t working, it may be because this tiny belt has snapped.

ANTENNA REPLACEMENT: The original Jaguar antennas are incredibly expensive, even when the mail order shops
put them on sale. If you’re not real concerned about originality, you can replace either the Merlin or Hirschmann
antenna and its delay relay with any of several antennas from J. C. Whitney or any local auto parts store for around $40.
It won’t have that 10-second delay before going down, but nobody’s ever figured out what that’s for anyway.

If you’re replacing a Merlin, there are aftermarket antennas with remote drive arrangements available for a few more
bucks if you’d like to locate the drive in the same place the original was. Hal Rogers of H. D. Rogers & Sons (page
709) says, “The unit that we sell which is a replacement unit, not exactly the original, and you may need a fitting kit as
well...It replaces DAC3542 or DAC4090 Jaguar part number.”

You don’t really need a remote type unit, though; you can install a cheap replacement with the motor right on the
bottom of the mast rather than remotely connected, so it’s in plain view within the trunk. You can fashion a cute
housing or cover around it if you wish. Typically, a remote drive antenna is used where space is a problem, but it’s not
a problem in the XJ-S; there’s no telling why Jaguar selected the remote Merlin unit for its early models.

When selecting an antenna, always insist on one that is “fully automatic”, meaning it raises or lowers automatically
when the radio is switched on or off; the “semi-automatic” antennas are electric motor driven, but you must control
them manually from a rocker switch installed somewhere. The difference is only a couple bucks, so it’s not worth the
effort to install and use a semi-automatic.

Also note that the ideal extended length for an FM antenna is about 31”. Any shorter or longer will give less-than-
optimum FM reception.

The aftermarket fully automatic antennas usually have two wires aside from the coax cable itself, one that should be
connected to 12V power and one that should be connected to a signal wire from the radio. If you are installing a
generic antenna, remove the original antenna along with the green delay relay attached to it. Connect the WK wire in
the car to the signal connection on the antenna. Connect the NP wire in the car to the 12V connection on the antenna.
If the antenna came with a fuse in the line you can include it in the circuit, but the XJ-S already has fuses in the circuits
so you can just discard it if you’d prefer. If the antenna has a black wire, connect the black wire in the car to it; if not,
make sure the housing of the antenna motor is grounded to the car, either by the mounting scheme or by connecting the
black wire to it.

Also, both the original antennas as well as the aftermarket units have a drain tube to dispose of rain water that runs
down the antenna into the housing; route the drain tube somewhere outside the car.

The antenna installation instructions also direct you to adjust the antenna trimmer on the radio. However, if your radio
has an electronic tuner (digital display instead of mechanical needle), it probably has no such adjustment.