Quick Reference: Top Twenty XJ Repair Issues
Here are some quick remarks on some of the more common repair issues and
questions. This list is not intended to replace actual trouble-shooting
and more detailed information can be found in the Archives or elsewhere
in the FAQ section.
Wipers don't self-park
The fault here almost always lies with the column mounted control switch
and not with the ³park switch² on the wiper motor. (Ser II, III)
Clunk, rattle, crunch noise over bumps
The upper bushings for the front shocks are almost always disintegrated
on these cars, allowing the shock to rattle against the inner
fenderwell. New replacement bushings are available separately and many
owners have successfully used generic bushings from a local parts
Also check the braces which run diagonally from the cowl to the fenders
(wings). Make sure they are tight....*very* tight. Anything thing less
will allow them to makes noise as the body flexes.
Power door locks inoperative or slow working
In about 80% of the cases the recalcitrant locks can be brought back to
life by removing the door trims and thoroughly lubricating all the
linkages and sliding points. Use an aerosol lubricant, silicone spray
works well. (Ser II and III)
Vibration felt when brakes applied
This is usually caused by warped brake rotors. Rotors can often be taken
to a machine shop and be resurfaced but most owners replace them with
new ones. The new ones are not too expensive and, since the job is
labor-intensive, it makes sense to just install new ones.
Speedometer inoperative or erratic
In about mid-1982 or so (for North American market cars, later for
rest-of-world) Jaguar switched from a cable-operated instrument to an
electric one. A transmission-mounted transducer produces a signal which
is sent to the speedometer. This transducer is the most common culprit
when you speedo acts up or just plain quits. Of course the connections
should be checked first. (SerIII)
Cruise control does not work
There are many possibilities here but often the fix is easy. First,
check the 2-amp fuse (#12 fuse, main fuse box). Next check the vacuum
bellows. This often leaks at the edges and can be cleaned and resealed
with silicone sealer. Don¹t forget to check the vacuum supply to the
bellows. The hose may have perished with age. (SeriesIII)
Engine will not crank
Assuming the battery is good, here are a couple of quick checks.
Examine the battery cables/terminals for cleanliness and tightness.
Ditto for the two firewall-mounted junction posts. Also try tapping the
starter relay (firewall mounted, silver, oblong). If tapping the relay
brings the starter back to life then replace the relay or disassemble it
and clean the contacts.
Power antenna won¹t retract all the way
Examine the mast for slight bends and gently reshape by hand, if needed.
Thoroughly clean the mast and lubricate it with an aerosol lube
(silicone, graphite, etc). In nearly all cases this is all that's
required. (Series II and III)
What is normal engine temperature?
Normal operating temperature is 88C-90C degrees. This is the beginning
of the green band on the temperature gauge (SeriesIII cars). If the
cooling system is in good order you should have no problem staying at
the 88C-90C range unless you are in extreme conditions, i.e.:
bumper-to-bumper traffic and/or ambient temps of 90-100F degrees. The
auxiliary electric fan will come on at about 95C degrees. In high
ambient temps I would say that anything over 100C degrees is cause for
concern. In cooler temps, anything over 90C merits investigation.
Identification of sensors on the water rail
On the fuel injected 6-cylinder cars, here's what the different sensors
are and what they do, starting from the front position.
First is the Thermotime Switch. This is a heated switch. It controls the
cold start injector. This switch operates only when the starter is
engaged and only when the engine is cold.
Next is the sending unit for the dashboard mounted temperature gauge.
Next is the fuel injection coolant temp sensor, which sends a signal to
the boot-mounted ECU (Electronic Control Unit). This sensor is an
important part of the fuel metering system.
Rearmost is the temperature switch for the air injection pump and the
canister purge system. On some non-North American and/or SeriesII cars
this sender is replaced by a vacuum switch for the EGR-equipped cars.
Identification of firewall relays
On 6-cylinder fuel injected cars, starting from the right (viewed from
driver's seat) you have:
The all-red Diode Pack. This is not actually a relay. It has several
diodes inside and directs the flow of voltage in the fuel pump circuit.
Next is the fuel pump relay.
Next is the ³main² relay, which feeds the injector ballast and a portion
of the fuel pump circuit.
Furthest inboard is the silver starter relay.
Note: The fuel pump and main relays can be inadvertently reversed. The
fuel pump relay is easily identified by the white/green wires, which are
not there on the main relay.
Incidentally, the 6-cylinder cars do not have a ³cold start² relay, the
12-cylinder cars do. The repair manual is confusing in this regard.
The SeriesII XJ6's with fuel injection have a large, single,
combination relay in place of the diode pack, main relay, and fuel
relay. This combination relay was also used on a few of the very
earliest SeriesIII cars.
Power windows inoperative
In a great many instances the cause is dirty contacts inside the window
switches. On SerII and III cars (perhaps Series I, too. Not sure...) the
switches can be easily accesses by removing the console cubby box and
releasing the switches from the rear by depressing the retaining tabs.
The switches can be removed, then, from the front. Do one at a time to
avoid mixing up the wiring.
A good aerosol contact cleaner (i.e., from Radio Shack) can be squirted
into the switches through the small holes in the sides. Or, many owners
have reported that the switches are relatively easy to disassemble and
the contacts can then be easily cleaned with a pencil eraser.
The Jag-lover archives have hours of reading on the very subjective
topic of tires. All owners agree that a high quality tire is called for.
Jaguar specifies a ³V-rated² tire for the XJ sedans and the vast
majority of owners insist that this recommendation be adhered to. The
V-rated tires have stronger casings and sidewalls.
The Series I and II cars used a 205/70x15 or ER70x15. The SeriesIII cars
also used a 205/70x15. However, about mid-way through the SeriesIII
production a 215/70x15 became standard issue on North American spec
cars. All V12 SeriesIII's used the 215/70 tire.
Interior lights inoperative from door switches
A few shots with your aerosol electrical contact cleaner will almost
always bring recalcitrant door jamb switches back to life.
Erratic headlamp operation
Detailed diagnosis can be found elsewhere in the FAQ's but in most cases
the fuses (in under-bonnet fuse box on Series III's) are dirty, loose,
or corroded. Easy fix.
Front wheel alignment on a XJ sedan is no more difficult than any other
³ordinary² car, and, in fact, is easier than many. Jaguar specified that
special links be used to compress the suspension to simulate a laden
condition. Since our Jags are seldom driven fully laden, this step is
The Jaguar adjustment shims are a bit unique but just about any
alignment specialist will have something suitable as a replacement.
Alignment of the rear wheels is limited to the camber adjustment only.
It is a very labor-intensive job and seldom required.
Automatic transmission fluid
Looked in your manuals and wondering what ³Type G² fluid is? You're not
alone. It is an obsolete designation. If you have a Borg-Warner
transmission (all 6-cylinder cars, V12's up to about 1978 or so) the
correct replacement is ³TypeF² or ³Type FA², both readily available.
Some owners use Dexron and report a softer shift with no problems.( If
you have a 12 cylinder car with the General Motors TH400 transmission
the correct fluid is Dexron and only Dexron.)
The horror stories are highly exaggerated. In many cases the problem is
not a faulty component but, instead, a faulty fuse and/or dirty, loose
connectors. If your Jag develops an electrical glitch, always start by
checking fuses and connectors. Always ! Don't assume a fuse is good just
because it looks OK. Test it or replace it to be sure.
Shocks are available from Koni, Monroe, Bilstein, KYB, Woodhead, etc.
However, the vast majority of owners seem to prefer and recommend the
Boge brand. Boge was the OEM supplier for many years.
Cold water slosh on turns
When using your air conditioner it is normal for condensation to
develop. The evaporator case has drains to let the condensate escape.
These drains often clog and the result is cold, brackish water pooling
in the case. It sloshes out on turns.
With the car safely elevated the drains can be cleared by probing them
with a piece of stiff wire. The two drain tubes can been seen existed
the floorboards on either side of the transmission tunnel, just aft of
where the engine and transmission come together.