Direction indicators and hazard warning lamps: Notes

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Land Rover Discovery, 2003 Land Rover Discovery, 2002 Land Rover Discovery, 2001 Land Rover Discovery, and 2000 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.

The BCU supplies reference voltages for the LH and RH indicators. When the direction indicator switch is used to select the LH or RH indicator position, an earth path is completed which signals the BCU that a request for direction indicator operation has been made. The BCU then communicates this request to the IDM which supplies an earth path for the coil of the relevant relay (LH or RH indicator relay). When the relay coil is energized, the relay contacts close and a voltage supply is provided via a resistor to the relevant direction indicators. The IDM controls the timing of the flash operations by continually removing and restoring the earth path to the direction indicator relay coil.

The BCU checks for the following inputs for performing the logic operations associated with the direction indicator lamps:

Ignition state.
RH indicators selected.
LH indicators selected.
Hazards selected.
Inertia switch hazard request.
One short indicator flash request (anti-theft system arming).
Two short indicator flash request (superlocking).
One long indicator flash request (anti-theft system disarming).
Alarm flashing indicators (anti-theft alarm triggered).

The following outputs are provided by the BCU as a result of the inputs received and the logical operations performed:

RH indicators enable.
LH indicators enable.
Direction indicator left message (link to IDM).
Direction indicator right message (link to IDM).