Discovery 2. Manual — part 772

NAVIGATION SYSTEM

DESCRIPTION AND OPERATION

87-9

Steering Wheel Switches
The steering wheel switches provide remote control operation for some of the navigation computer functions. The
switches can be used to select between the radio/CD/navigation modes, to adjust the volume (in all modes) and to
select search/preset up/down for radio and CD operation.

Remote Control Interface Unit
The remote control interface unit converts the analogue signals from the steering wheel switches into digital signals
for use by the navigation computer. The remote control interface unit is installed in a bracket immediately below the
navigation computer.

The radio remote switches form a resistance ladder between two wires with the resistance across wires dependent
on which switch is pressed. The remote control interface unit monitors the two wires and converts their input into
Instrument (I) bus protocol messages, which it outputs on a dedicated serial link to the navigation computer.

NAVIGATION SYSTEM

87-10

DESCRIPTION AND OPERATION

NAVIGATION SYSTEM

REPAIRS

87-11

REPAIRS

Interface electronic control unit (ECU) -
remote control

$% 86.53.15

Remove

1. Remove navigation display unit.

+

NAVIGATION SYSTEM, REPAIRS,

Display unit.

2. Remove automatic temperature control unit.

+

AIR CONDITIONING, REPAIRS, ECU

- air temperature control.

3. Remove 2 nuts securing interface carrier

bracket, carefully pull bracket out of fascia.

4. Release interface ECU from bracket,

disconnect multiplug and remove ECU.

Refit

1. Secure interface ECU in bracket and connect

multiplug.

2. Carefully position carrier bracket in fascia,

secure with nuts and tighten to 10 Nm (7 lbf.ft).

3. Fit automatic temperature control unit.

+

AIR CONDITIONING, REPAIRS, ECU

- air temperature control.

4. Fit navigation display unit.

+

NAVIGATION SYSTEM, REPAIRS,

Display unit.

M86 5760

M86 5762

NAVIGATION SYSTEM

87-12

REPAIRS

Display unit

$% 86.53.20

Remove

1. Fit tool LRT-86-009 into slots ensuring correct

handed key is in correct slot.

The tools are stamped either 'TOP L' or 'TOP
R', ensure the stamping is facing upwards
when removing the unit.

2. Pull display unit from fascia.

3. Disconnect 3 multiplugs and 2 coax cables

from display unit and remove unit.

4. Push display unit retaining clips inwards and

remove keys.

Refit

1. Position display unit to fascia, connect

multiplugs and coax cables.

2. Push display unit into fascia until retaining clips

engage.

3. Enter security code and check system is

operational.

M86 5824

M86 5825