Instruments

INTRODUCTION

Vehicle instrumentation comprises two electrically connected computer based Systems; a Control System which monitors manually operated switch conditions to implement low current switching of the vehicle electrical devices. and a Display System which provides visual indication of both journey information and monitored vehicle conditions on the instrument pack. Each system operates under microprocessor control with timed functions being performed by software.


DISPLAY SYSTEM

The Display System presents information in alphanumeric, graphic and bar-graph formats using a Vehicle Condition Monitor (VCM) and vacuum fluorescent tubes. These devices are positioned to the side and beneath two moving coil instruments (speedometer and tachometer) which are located at the fascia centre.

The vacuum fluorescent tubes are illuminated at one of two intensities; bright when the vehicle sidelights are OFF, and dimmed when the vehicle sidelights are ON. In the dimmed mode, the moving coil instruments are also illuminated and the intensity of all displays can be varied by means of a potentiometer located on the left-hand side of the column switchgear.

Displayed vehicle conditions can be divided into two categories; those which are shown during normal vehicle operation (normal displays), and those which are shown only when a fault exist (hazard/fault displays). Information for all displays is derived, from either the Central Processing Unit (CPU) or direct from sensors.


Normal Displays

Normal displays are derived from instrument pack inputs. These inputs are processed to drive the following devices:
Speedometer.
Odometer.
Tachometer.
Battery condition indicator.
Oil pressure indicator.
Coolant temperature indicator.
Fuel level indicator.
Gearbox indicator (automatic only).
Direction indicator symbol.
Headlamp main beam symbol.
Caravan symbol.

HAZARD/FAULT DISPLAYS

Hazard/fault information is shown on the VCM as a two line message displayed below an appropriate International Standards Organization (ISO) graphic symbol. Each symbol is displayed within either a red or amber surround which identifies the condition as either critical or non-critical.

Critical (red) and non-critical (amber) hazard/fault displays are derived from instrument pack inputs and are as follows:

Fasten seatbelt.
Circuit failure (either 1,2 or 3).
Bulb failure.
Fuelling failure (3.6 litre engine only).
Brake failure.
Brake pad low.
Brake fluid low.
Coolant level low.
Park brake on.
Washer fluid low.
Door open.
Boot open.
Anti-lock failure (ABS only).

Should two or more hazard/fault conditions exist, each condition is displayed at 2 second intervals in sequence. In addition, fault conditions are re-presented immediately following a two second display test each time the ignition is switched ON.

A facility exists which permits condition messages to be erased thus allowing trip computer information to be presented. This facility is selected by operating a CLEAR push-button on a trip computer keyboard. When selected, the function is maintained until another fault condition is detected and the facility revoked.

A test facility is included which, provided that no red condition exists, performs display sequencing of the ISO symbols when a VCM push-button on the trip computer keyboard is operated. At the end of the test sequence, normal system operation is resumed