Discovery 2. Manual - part 780

INSTRUMENTS

DESCRIPTION AND OPERATION

88-29

Water in fuel filter warning lamp 

The water in fuel filter warning lamp within the instrument pack utilises an amber LED and a clear legend. On vehicles 
with diesel engines the LED is illuminated when the water sensor detects water is present in the fuel filter, providing 
the driver with a visible warning. 

When the ignition is switched on, the instrument pack illuminates the LED to provide a self-check, providing there is 
no water present in the fuel filter it will remain illuminated for 3 seconds or until the ignition is switched off.

The power input for the LED is supplied by the instrument pack via fuse 27. The water sensor provides the earth path 
to illuminate the warning lamp. The voltage on the earth path from the sensor to the instrument pack is as follows:

l

< 1.8 volts = warning lamp on.

l

> 7.7 volts = warning lamp off.

INSTRUMENTS

88-30

DESCRIPTION AND OPERATION

Water sensor 

On vehicles with diesel engines a water sensor is located in the bottom of the fuel filter. The sensor utilises the 
different resistance properties between water and diesel fuel to determines the presence of water in the fuel.

The sensor receives a battery voltage supply from the fuel pump relay. The sensor output is supplied to the instrument 
pack. The water sensor provides the earth path to illuminate the warning lamp. 

l

< 1.8 volts = warning lamp on.

l

> 7.7 volts = warning lamp off.

INSTRUMENTS

DESCRIPTION AND OPERATION

88-31

Seat belt warning lamp

The seat belt warning lamp within the instrument pack utilises a red LED and a clear legend. The BCU utilises a switch 
in each of the front seat belt buckles to determine if a seat belt is not fastened.

When the ignition is switched on, the BCU illuminates the LED for 6 seconds or until the BCU determines that a seat 
belt is fastened which extinguished the warning lamp. This provides the driver with a visible reminder that the seat 
belts are not fastened.

The instrument pack provides the self-check if the diagnostic connector fails.

The power input for the LED is supplied by the instrument pack via fuse 13. The BCU provides the earth path to 
illuminate the seat belt warning lamp.

The seat belt buckle switches complete the earth path in the BCU sensing circuit, the BCU commands the instrument 
pack to switch on the seat belt warning lamp.

The BCU earth path to the seat belt buckle is as follows:

l

< 1.8 volts = warning lamp off.

l

> 7.7 volts = warning lamp off.

INSTRUMENTS

88-32

DESCRIPTION AND OPERATION

Transmission high temperature warning lamp

The transmission high temperature warning lamp within the instrument pack utilises a red LED and a clear legend. 
On vehicles fitted with automatic gearboxes, the transmission high temperature warning lamp is utilised to provide the 
driver with a visible warning that the automatic gearbox oil has exceeded a normal operating temperature. The 
warning lamp will extinguish if the gearbox oil returns back to normal operating temperature.

When the ignition is switched on, the instrument pack illuminates the LED to provide a self-check, providing there is 
no fault it will remain illuminated for 3 seconds or until the ignition is switched off.

The power input for the LED is supplied by the instrument pack via fuse 13. The temperature sensor provides the 
earth path to illuminate the transmission high temperature warning lamp.

The transmission high temperature warning lamp is controlled according to the voltage present on the temperature 
sensor to instrument panel earth path:

l

< 1.8 volts = warning lamp on.

l

> 7.7 volts = warning lamp off.