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Lotus Elise / Lotus Exige. Instruction - part 51

Page 7

Lotus Service Notes

Section GH

GH.6 - TYRE PRESSURE MONITORING SYSTEM (TPMS) - USA ONLY

All USA Elise/Exige models from ‘08 model year onwards are ﬁtted with a tyre pressure monitoring system.

A sensor incorporated into each of the tyre valves monitors the air pressure inside the tyre, and supplies an

onboard control module with this data by radio transmission. If any tyre pressure should fall below 75% of the

recommended value, an alert message is sent to the instrument panel, and the tyre pressure tell tale

will light up amber. The fuel gauge display will then be overwritten with a message to indicate which tyre is

concerned, with text such as:

LF Low (left hand front tyre low pressure). This message will show for 5 seconds

before the display reverts to the fuel level bar graph, but will repeat for 5 seconds at 30 second intervals.

The TPMS incorporates self-malfunction recognition, and if a fault is detected, the tell tale will ﬂash for one

minute and then remain constantly lit. The LCD panel will also ﬂash ‘TPMS FAULT’ for 5 seconds, and repeat

at 30 second intervals; no indication of low tyre pressure will be displayed.

Tyre ﬁtters and service technicians should be made aware that TPMS is ﬁtted, and that the tyre valves

include pressure sensors. If the emergency tyre inﬂator aerosol has been used, it will be necessary to renew

the tyre valve/pressure sensor. If a fault is indicated after wheel or tyre replacement, it is likely that a sensor

has been incorrectly ﬁtted or damaged. If a tyre valve is renewed, or is moved to a different wheel position, the

TPMS will automatically identify the new conﬁguration.

Note that the pressure sensors are powered by integral batteries, with an average service life of 10 years.

It is recommended to renew all pressure sensors at this time interval.

If renewing a wheel, ensure that only a TPMS compatible wheel is used, as the installation angle of the the

tyre valve is modiﬁed to accommodate the pressure sensor. Compatible cast wheels are identiﬁed by 'TPMS'

within one of the recesses in the hub mounting face. On TPMS compatible forged wheels, the proﬁle of the

wheel rim outboard of the central well, is modiﬁed in order to allow local machining around the valve hole on

the inside of the rim to provide a shallower installation angle. If no machining is evident, the wheel is not TPMS

compatible. In addition, a batch code is engraved onto the inner rim in the form of 'PS123456'. The ﬁrst three

numbers indicate the week and year of manufacture, and any wheel with a code of PS267### (week 26 of

2007) or later, will be TPMS compatible. TPMS type wheels may be ﬁtted on all cars.

Lotus Service Notes Section HG

Page 1

STEERING

SECTION HG

Sub-Section Page

General Description

HG.1

Steering Wheel

HG.2

Upper Column Assembly

HG.3

Intermediate Column

HG.4

Front Wheel Alignment & Rack Gaiters

HG.5

Rack & Pinion Assembly Removal/Replacement

HG.6

Adjustment of Rack Bar Thrust Pad

HG.7

Lotus Service Notes Section HG

Page 2

Upper column

assembly

mountings

Track rod
end

Intermediate
column

Lower
u/j

Upper u/j

Rack mounting
plinth

Thrust pad
adjuster

Rack housing

Gaiter

Track rod

h55

HG.1 - GENERAL DESCRIPTION

The steering system of the Elise comprises a telescopically collapsible upper column assembly, connect-

ing to a rigidly mounted rack and pinion assembly via a universally jointed intermediate shaft. The steering
rack tie rods connect to rearward facing steering arms bolted to the forged steel front hub carriers, with geom-
etry providing 30% Ackermann effect, and a toe-out on bump characteristic. No power assistance is provided.
Prior to June '04, the steering rack assembly used a one-piece, alloy, pinion/rack housing, superseded after
that time by a cast alloy pinion housing mated to a tubular steel rack housing.

The upper column is fixed to the scuttle beam, with the column upper bearing carrier also providing

mountings for the steering lock and column switches. 'Break out' inserts fitted in the column upper mounting
flanges, allow for telescoping of the column in a frontal collision. The steering rack assembly, which provides
2.4 turns from lock to lock at a 15.8:1 ratio, is rigidly mounted inside a chassis transverse extrusion behind the
top wishbone rear pivots.

HG.2 - STEERING WHEEL

Non Airbag Type: The alloy three spoke steering wheel, has a leather trimmed rim and moulded rubber
covered spokes, and is secured to the column via a 36 spline boss. The horn button is mounted in the steering
wheel centre pad which is supported by a collapsible steel spider bolted to the hub of the wheel. The positive
feed to the horn button is supplied via a spring loaded contact housed in the column switch carrier, and a slip
ring mounted on the forward side of the wheel. The earth contact of the button is connected to a terminal on the
spider.
Airbag Type: The alloy three spoke steering wheel has a leather trimmed rim and moulded rubber covered
spokes which incorporate horn buttons in the outer ends of each of the nominally horizontal spokes. An airbag

Lotus Service Notes Section HG

Page 3

module is incorporated in the centre of the wheel, and uses a rotary coil unit to maintain cable continuity to the
airbag and horn buttons.

To Remove Steering Wheel (non airbag type)
1.

Pull off the centre trim pad with horn
button, and disconnect the two horn
leads.

To allow access for a steering wheel
puller tool, it is necessary first to remove
the column shroud:

Release the four screws securing the
shroud upper section, turning the steer-
ing wheel as necessary to permit access.

Pull out the grommet from around the
ignition switch, and remove the three
screws securing the lower shroud.

If necessary, disconnect or remove the
trip/panel lights control button from the
lower shroud.

Remove the nut securing the steering wheel boss to the column. Match mark the boss and column to
enable alignment to be maintained on re-assembly.

Use a suitable steering wheel puller tool to locate behind the steering wheel boss and bear against the
end of the column.
CAUTION: If excessive force is applied to either the wheel or column without an appropriate
puller, the telescoping mechanism of the outer column may be overridden, necessitating column
replacement.

If necessary, unclip the slip ring from the steering wheel boss and withdraw with the horn lead. Withdraw
the column bearing preload spring.

To refit the steering wheel, reverse the above procedure with the following notes:

Clip the horn slip ring to the steering wheel boss with the turn indicator cancelling vane on the left hand
side.

Ensure that the column bearing preload spring is fitted over the inner column before fitting the wheel with
the match marks aligned. If re-alignment is necessary, see later.

Torque tighten the steering wheel to column nut to 25 Nm.

Column upper shroud

Lower shroud
mounting
bracket

Column lower
shroud

b258a

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