| Instrument Problems
Not with standing the problems that these units suffer from,
the Pre facelift models have the most ugly looking instrument
binnacle ever fitted to a Jaguar but luckily there are a number
of options available to make a bad job look a whole lot nicer.
for further information follow the Upgrade Options link. If
on the other hand you’re here because you have an issue
with your instrument binnacle please read on.
Instrument problems on the XJ-S are common place and seem
to fall into the following categories..
- Inadequate illumination of the gauges at night
- Gauges giving incorrect or erratic information
- Flickering warning lamps
In this article we’ll explore the various reasons for the faults and explain how to improve the situation.
If you think your unit is working correctly, think again.
Unless you have stripped it down and done a fair bit of remedial
work, your instruments are most likely lying to you, the illumination
is not as good as it could be and you could, in the worst
instance, be damaging your engine.
Firstly lets take a look at the stock unit and how it works.
Illumination: The binnacle has 5 x 2.2 watt
cap less lamps fitted inside it (2 around the speedometer
(1 on earlier models), 2 x below the monitor gauges and 1
around the rev counter) these are covered by small translucent
green plastic domes. Light from the lamps shines onto the
rear of the face panel and is reflected back onto the face
of the instrument in question to give a nice even glow. The
back of the face plate is painted matt dark grey and the internal
cavity is made from white plastic.
Gauges: The information/electrical signals
for the gauges come from various sensors around the car.
- Temperature is from a sender mounted on the
LH bank of the
engine V12 and on the hot water rail for the
induction manifold on the 3.6.
- Oil pressure is via a sender on the Oil filter interface.
- Battery charge is from the terminal post via fuse 4.
- Fuel level from a sender in fuel tank.
- The revolution counter gets its signal from the the ignition
amplifier.
- Speedometer from a transducer fitted to the LH side of the
Gearbox (GM400)
- The signals enter the instrument binnacle through conventional
wires
via two large plugs in the rear of the main instrument
body where
they pass via the Printed Circuit Mat (PCM) to
mounts on the gauge in
question which then respond to the
data they are receiving accordingly.
The same is true of the warning lamps which again get information
from various sensors the location of which are beyond the
scope of this article.
It can be seen clearly that there are some obvious reasons
why problems exist. Bad connectors are by far the most common
cause. Another is wiring which can snap due to vibration and
hardening cause by the heat from the engine. On the whole
the senders themselves are fairly reliable although these
can and do, break down occasionally.
When all is said and done, if you are confident that the
wiring is OK and that all earths and connectors are clean,
tight and firm but you are still getting problems, before
shelling out bucket loads of money on new senders your should
give consideration to the cheapest option; that of removing
and overhauling the instrument binnacle
We offer a replacement
unit that just requires the use of your existing speedometer
and rev counter and these units have been upgraded and overhauled
to correct the various problems encountered. But if you fancy
having a go yourself. the Instrument Problems article explains
the procedure to complete all the necessary work and is achievable
by the competent owner. |
