Discovery electrical Manual - part 81

THEFT ALARM SYSTEM (NAS)

T2

CIRCUIT OPERATION

3

VEHICLE STATUS INDICATION

Vehicle status is indicated by up to three devices:

1. Hazard lamps

2. Theft Alarm LED (contained in the Instrument

Cluster (Z142))

3. Horns (K128, K134)

Hazard Lamps

When the vehicle arms in either mode, the hazard
lamps will flash up to three times when the alarm is
armed and one time when disarmed.

Theft Alarm LED

Slow Flash: Immobilised or immobilised and ar-
med

Rapid Flash: Volumetrically armed

Intermittent Rapid Flash: Perimetrically armed

No Flash for 10 Seconds: Mislock

Continuous: Driver’s door open (or ignition on)
and immobilised

NOTE: The Theft Alarm LED may also be used to
indicate other conditions.

HANDSET TRANSMITTER RESYNCHRONISA-
TION

The Theft Alarm Unit (Z163) will remain
synchronised with the handset unless:

The handset’s batteries have been removed

The vehicle’s battery has been disconnected

NOTE: All handsets must be resynchronised when
the vehicle’s battery has been disconnected.

To resynchronise a handset the vehicle must be in
an unlocked and disarmed state. Resynchronisation
consists of 4 presses of either the lock or unlock
button.

HANDSET LOW BATTERY WARNING

When the handset batteries are low, the Theft Alarm
Unit (Z163) will enter the “low battery mode”. The
Theft Alarm LED will flash to indicate “low battery
mode”, and the hazard lamps will not flash when the
alarm is disarmed.

POWER UP MODE

The alarm system always remembers the state it
was left in when power was removed. If the alarm
powers up in an alarmed state, it will enter a special
”power up mode”.

BUILT IN TEST PROCEDURE

The built in test procedure is accessed as follows:

1. Starting conditions: ignition off, doors unlocked,

alarm disarmed, bonnet switch depressed.

2. Carry out instructions 3 to 7 within 2 seconds.

3. Release bonnet switch.

4. Switch ignition on.

5. Open driver’s door.

6. Switch ignition off.

7. Switch ignition on.

If alarm is correctly accessed, the horns will sound
briefly and the Theft Alarm LED and hazard lamps
will flash. The following checks can then be made:

THEFT ALARM SYSTEM (NAS)

T2

CIRCUIT OPERATION

4

Perimetric Testing

1. Open and close driver’s door or tailgate – Theft

Alarm LED and Hazard lamps will flash.

2. Depress and release bonnet switch – Theft

Alarm LED and Hazard lamps will flash.

3. Pull the driver’s door sill button up – Theft alarm

LED and Hazard lamps will flash.

4. Turn driver’s door key lock cylinder – Theft Alarm

LED and Hazard lamps will flash.

HANDSET INITIALISATION

The Theft Alarm Unit (Z163) must be programmed
whenever handsets are replaced. The serial
communications line is used to activate the “learn
mode” of the Theft Alarm Unit (Z163). Then the
handset(s) to be initialised must be made to transmit
their coded data to the Theft Alarm Unit (Z163).

NOTE: All handset(s) must be programmed during
the same learn mode period. It is not possible to
simply add a handset to the Theft Alarm Unit (Z163)
which has been programmed to other handsets.

When the “learn mode” of the Theft Alarm Unit
(Z163) has been accessed, the handset(s) are
programmed using the following procedure:

1. Starting conditions: Theft Alarm disarmed and

vehicle mobilised.

2. Press the handset unlock button a minimum of 8

times.

3. If the handset has been correctly programmed,

the horn will briefly sound and the hazard lamps
will flash once.

4. The next handset, up to a maximum of 4, can

now be programmed using the same procedure.

NOTE: It is very important that each handset be
programmed separately. If the Theft Alarm Unit
(Z163) receives key presses from two handsets,
then neither handset will be programmed.

The “learn mode” is terminated using the serial
communications line. If the Theft Alarm Unit (Z163)
would not accept reprogramming, the original
handset(s) will still function.

THEFT ALARM SYSTEM (NAS)

T2

5

CIRCUIT DIAGRAM

REV: 06/97

S204

30

F 1

15 A

E200

15

F 5

10 A

P127
Satellite Fuse
Box 1

Z163
Theft Alarm Unit

P

25

GK

10

C225

HJ3

BO

GK

30

F 4

30 A

P125
Engine Compart-
ment Fuse Box

PN

8

C274

S2089

11

C274

S2017

B

1

C101

See Ground Dis-
tribution

See Fuse Details

Z147
Window Lift ECU

See Fuse Details

HJ4

PR

18

9

C287

KB

17

C225

8

C2083

X318
Data Link Con-
nector (OBDII)

Up to VIN 550522
& 717858

THEFT ALARM SYSTEM (NAS)

T2

6

CIRCUIT DIAGRAM

S332

Z163
Theft Alarm Unit

3

3

WB

20

20

1

BN

21

C225

C277

C335

2

C335

B

E401

26

WB

C225

Antenna

See Ground Dis-
tribution

Shield

X213
Alarm Sensor

13

SCR