Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Hazard Warning Lamps

The hazard warning lamps are controlled by a non-latching switch in the centre of the instrument panel. The hazard warning lamps operate at all times when selected and are not dependent on the ignition power mode.

When the hazard warning lamps are selected on, all of the turn signal indicators operate as previously described and both left and right turn signal indicators in the Instrument Cluster (IC) also flash. The hazard warning lamps flash at a rate of 400ms on and 400ms off. When the hazard warning lamps are active, they override any request for turn signal indicator operation.

If a trailer is fitted, the trailer turn signal indicators will flash at the same frequency as the vehicle turn signal indicators. The trailer warning indicator in the IC will also flash. If a trailer turn signal indicator bulb is defective, the trailer warning indicator will not flash.

The hazard warning lamps can also be activated by a crash signal from the Restraints Control Module (RCM). This is received by the CJB which activates the hazard warning lamps. The hazard warning lamps can be cancelled when crash mode is cancelled by the RCM.


Several different types of trailer socket can be fitted to the vehicle depending on market specifications. Refer to the Electrical Reference Library for specific socket details.

The CJB monitors the turn signal indicators and can detect if more than two lamps are fitted. When a trailer is detected, the trailer warning indicator in the IC will flash in synchronization with the turn signal indicator.

If one or more of the turn signal indicators on the vehicle or the trailer are defective, the trailer warning indicator will not flash to alert the driver to the bulb failure.


Daytime Running Lamps (DRL) are a market requirement in certain countries.

For market information and DRL functionality refer to the DRL section.

For additional information, refer to: Daytime Running Lamps (417-04 Daytime Running Lamps, Description and Operation).

Halogen Headlamps

The DRL and Side lamps use the same string of LED's. The DRL operate at a higher intensity than the side lamp illumination.

Xenon Headlamps

The DRL's and Side lamps use the same string of LED's. The DRL operate at a higher intensity output than the side lamp illumination.


For details of the trip computer function refer to Information and Message Centre.

For additional information, refer to: Information and Message Center (413- 08 Information and Message Center, Description and Operation).



The dimmer rotary thumbwheel controller is located adjacent to the headlamp LEVELLING control (when fitted) in the auxiliary lighting switch.

The dimmer control provides a PWM output to control the illumination brightness of the Instrument Cluster (IC), switches and other instrument panel illumination.

The dimmer rotary thumbwheel is connected to a rheostat and a high side switch. The rheostat is a variable resistor which provides a high or low resistance according to its set position. This output is passed to a switchable capacitor or a high side switch. The high side switch uses the output from the rheostat to determine the switching frequency of the capacitor which provides the PWM output of between 8 and 12V to determine the brightness of the illumination.



  1. Side lamps
  2. Headlamp high beam
  3. Turn signal indicators
  4. Rear fog lamps
  5. Auto high beam
  6. Adaptive front lighting system

The AFS warning indicator is activated by a high speed CAN bus message from the headlamp LEVELLING control module to the instrument cluster.

The remainder of the exterior lighting warning indicators are activated by the CJB using medium speed CAN bus messages to the instrument cluster.



The diagnostic socket is located in the lower instrument panel closing panel, on the driver side, below the steering column. Various lighting system functions are monitored by different systems which can store fault information. This can be retrieved using a Land Rover approved diagnostic system.



     Central Junction Box

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