Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Door Mirrors


There are 2 modes of heated door mirror operation; manual and automatic.

Manual operation is activated by pressing the Heated Rear Window (HRW) switch . When the switch is pressed, the status LED in the switch illuminates and the door mirror heater element is energized. Manual operation is discontinued when the HRW switch is pressed a second time, between 5 and 21 minutes have elapsed (dependent on ambient air temperature), or the engine stops.

Automatic operation is initiated when low ambient air temperatures are experienced. The CJB receives the ambient air temperature value from the Engine Control Module (ECM) on the HS CAN Powertrain bus. The CJB converts the ambient air temperature value to an on-time percentage and transmits it on the MS CAN Body bus to the two door modules, which then energize the door mirror heating elements accordingly. The on-time percentage is increased while the windshield wipers are on.



Adjustment is enabled while the ignition is on and, provided the driver door is not opened, for up to five minutes after the ignition is switched off.

When the L or R select switch is pressed, the tell-tale LED in the switch illuminates and the adjustment switch can be used to move the mirror glass of the related door mirror. The driver door switchpack interprets adjustment switch movement and transmits it to the DDM on a LIN bus. Adjustment signals for the passenger door mirror are transmitted from the DDM to the PDM on the MS CAN Body bus. On receipt of an adjustment signal, the appropriate door module connects a power supply and ground to the relevant adjustment motor to produce the required movement of the mirror glass. When the adjustment switch is tilted in the opposite direction, the door module reverses the polarity of the adjustment motor, to move the mirror glass in the opposite direction.

Memory Recall

The vehicle can memorize up to three different positions for the door mirrors, the driver seat and the steering column. This enables three different drivers to achieve their optimum driving position at the touch of a button.

The memory store and memory pre-set switches are located on the driver door casing.

The memory function is incorporated into the CJB.

Memory Recall

The memory switches form a resistive ladder in hardwired connections with the driver seat switchpack. When a position is stored or recalled for channels 1 to 3, the driver seat switchpack transmits the information on a LIN bus to the seat memory module, which relays it to the CJB on the MS CAN Body bus. It is then relayed to the door modules. Each door module evaluates the recall or storage command and performs the necessary adjustments to the exterior mirrors. If a manual mirror adjustment is selected while a memory recall is operating, it will over-ride the memory recall movement.

For mirror memory to operate, the mirror adjustment potentiometers must deliver a voltage value in the range of 80 mV - 4.8 V. Should a voltage applied be outside of this range the mirror will not operate when memory is selected

Reverse Dipping

Reverse dipping can be enabled and disabled in the vehicle set-up section of the vehicle information and settings menu. If reverse dipping is enabled, both of the exterior mirrors automatically dip, to provide a better view of  the kerb, when the ignition is on and reverse gear is engaged. The mirrors return to their original position immediately reverse gear is disengaged, or if the vehicle speed in reverse exceeds 7.5 mph (12 km/h).

The dipped positions of the door mirrors are stored in the CJB, which signals the front door modules on the MS CAN Body bus to move the mirror glass into and out of the dipped positions. Reverse gear engagement and disengagement is signaled to the CJB on the HS CAN Powertrain bus by the TCM (Transmission Control Module) (automatic transmission) or on hardwire by the reverse switch (manual transmission).

The dipped mirror position can be adjusted using the mirror switches while reverse gear is selected and the ignition is on. Any adjusted position will be automatically saved to whichever memory pre-set function is in operation at the time.

On vehicles with automatic transmission, reverse gear must be selected for approximately 0.5 second before the door mirrors move to the dipped position. The time delay prevents nuisance movement of the door mirrors when the transmission selection moves between Park and Drive.

Mirror Foldback

If mirror foldback is incorporated, pressing the L and R mirror select switches at the same time folds the door mirrors. Pressing both of the switches again unfolds the door mirrors. Operation of mirror foldback is inhibited at speeds over 70 mph (112 km/h). If the door mirrors are accidentally knocked out of synchronization (i.e. with one mirror folded and the other in the normal position), pressing both of the switches again resynchronizes them.

On vehicles with mirror foldback, automatic operation can be enabled and disabled using Land Rover approved diagnostic equipment. When automatic operation is enabled, the door mirrors automatically fold and unfold when the vehicle is locked and unlocked using the smart key.

However, if the mirrors are folded using the mirror switches, they will not automatically unfold when the vehicle is unlocked.

To prevent the foldback motors from overheating, the foldback function is disabled for 3 minutes if the mirror foldback function is selected ten times within 60 seconds. On the tenth selection within 60 seconds, the door mirrors will only unfold; if the selection is for the door mirrors to fold, the selection is ignored.



NOTE: A = Hardwired; O = Local Interconnect Network (LIN) bus; AN = High Speed (HS) Controller Area Network (CAN) Powertrain bus; AO = Medium Speed (MS) CAN Body bus.


  1. CJB
  2. TCM
  3. ECM
  4. PDM
  5. DDM
  6. Driver Seat Module (DSM)
  7. Rear view mirror
  8. Driver seat switchpack
  9. Seat memory switchpack
  10. Driver door switchpack
  11. Right door mirror
  12. Left door mirror (containing the AAT sensor)
  13. Ground
  14. Power supply
  15. Reverse switch (manual transmission vehicles)
  16. RJB
  17. BJB
  18. Battery


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    PRINCIPLES OF OPERATION For a detailed description of the Rear View Mirrors, refer to the relevant Description and Operation section in the workshop manual. REFER to: Interior Rear View Mirror (501-09

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     Turn Signal and Hazard Lamps

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     Windshield Wiper Fast/Slow/Single Wipe - Operation

    OPERATION Slow Wipe When the driver moves the wipers and washers control switch to the slow wipe position, the Central Junction Box (CJB) detects a Local Interconnect Network (LIN) bus message and energizes the wiper on/off relay in the Battery Junction Box (BJB). Power flows to the relay contacts o

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