Land Rover Defender Electrical Library 3rd Edition Nas Rover Manual

							Electrical Library 
						

							CONTENTS
DEFENDER 90 NASREV: 9/97INTRODUCTION.................................................................................1
FUSE DETAILS....................................................................................1
CIRCUIT OPERATION
ENGINE IMMOBILIZATION (CODING) ................................1
STARTING AND CHARGING  ...............................................2
GENERIC ENGINE MANAGEMENT SYSTEM (GEMS)   .....4
SEAT BELT WARNING  .......................................................12
AIR CONDITIONING.............................................................13
HEATER BLOWER.................................................................16
HEATED REAR WINDOW  ...................................................17
WIPERS AND WASHERS  ....................................................19
EXTERIOR LAMPS - Brake and Reverse Lamps  ........................23
EXTERIOR LAMPS - Head, Side and Number Plate Lamps ...........24
EXTERIOR LAMPS - Lights On Alarm   ....................................26
INDICATORS / HAZARD WARNING LIGHTS   ..................27
INTERIOR LAMPS  ...............................................................29
INTERIOR ILLUMINATION  ................................................30
INSTRUMENTS  ....................................................................32
CLOCK  ..................................................................................35
CIGAR LIGHTER  ..................................................................36
IN-CAR ENTERTAINMENT   ...............................................37
IGNITION AND SHIFT INTERLOCK  ..................................39
CONNECTOR DETAILS........................Indexed by connector number 
						

							INTRODUCTION
DEFENDER 90 NAS1This Reference Library is designed to be used in conjunction with the Circuit Diagrams
as an aid to the diagnosis of electrical faults. When diagnosing faults using TestBook, the
circuits and library will prove a useful source of additional information, enabling you to
study the operation of the circuit, isolate the suspect sub-circuit and quickly locate
connectors, without unnecessary removal of trim. The library has 2 sections; Circuit
Operation and Connector Detail.
1. Circuit Operation
This section contains a description of operation for every circuit diagram, with the
exception of Power and Ground Distribution. Each description attempts to detail
current flow in the circuit under all operating conditions. Wires are identified by their
color, and where appropriate, their corresponding connector and pin numbers. Where
circuits contain microprocessor control units, the descriptions concentrate on the
system inputs and outputs.
2. Connector Detail
This section is effectively an index of every electrical connector on the vehicle,
including header joints and eyelets. A page is dedicated to each connector, with the
information presented in a standard format. The connector number is displayed on
each page header to ease reference. Connector Detail information comprises:
· Connector Number - The assigned number, prefixed “C”.
 
· Connector Name - Usually derived from the component to which the connection is
made.
 
· [number] Way - Number of pins if applicable. This is a statement of the pin
locations in the connector housing (receptacle) and should not be confused with the
number of wires actually populating these locations, which is usually less.
 
· Male/Female - If applicable, shows whether the connector pins (NOT the housing)
are of a Male or Female gender. Generally, connectors mating directly to a
component have Female pins.
 
· Color - If applicable, the color of the connector housing is shown. NATURAL is
used to describe connectors with a clear/translucent plastic finish.
 
· Location Statement - Used in conjunction with the photograph to determine the
exact location of the connector.
 
 
  
						

							INTRODUCTION
2DEFENDER 90 NAS 
 
 
· Photograph - Shows the location of the subject connector. In most cases, the
photograph will indicate the amount of trim removal necessary to reveal the
connector.
 
· Face View - An outline of the connector housing, drawn from the front, showing pin
numbers (if applicable).
 
· Pin-out Table - A three column table, detailing the color and position of each wire
in the connector:
Cav - The connector pin (cavity) number.
Color - The color of wire populating the connector pin.
Cct - Shows the derivatives of vehicle using the wire. ALL means
applicable to all vehicles in the range. 
						

							FUSE DETAILS
DEFENDER 90 NASREV: 9/971INTRODUCTION
The following tables give details of power supply through the engine and passenger
compartment fuse boxes.
Note:Some fuse numbers may be followed by a letter, either an ‘E’ or a ‘P’. ‘E’ denotes
a fuse located in the engine compartment fuse box, and ‘P’ a fuse located in the
passenger compartment fuse box.
Engine Compartment Fuse BoxLinkRatingFunction1100 AmpLink 3, Link 4, Link 5, Link 6, Fuse 1 (E), Fuse 2 (E), &Fuse 3 (E).260 AmpFuse 13 (P), Fuse 14 (P), Fuse 15 (P), & Fuse 16 (P).360 AmpLighting switch.430 AmpLighting switch.560 AmpFuse 2 (P), Fuse 3 (P), Ignition switch, & Starter relay.630 AmpHeater rear screen relay.FuseRatingFunction130 AmpInterior Lamp Unit.220 AmpColumn switch, Multi-function ECU, Interior lamp -front, Analogue clock, Key-in sensor.330 AmpEngine immobilisation ECU.410 AmpNot used.530 AmpHazard warning switch.615 AmpEngine management relay module.720 AmpEngine management relay module. 
						

							FUSE DETAILS
2DEFENDER 90 NASREV: 9/97Passenger Compartment Fuse BoxFuseRatingFunction115 AmpInstrument pack, Multi-function ECU, Headlamp relay,Interior lamp - rear, & Warning light check unit.210 AmpRadio cassette player.35 AmpDiagnostic socket.415 AmpBlower motor - front.57.5 AmpRadio cassette player.615 AmpRadio cassette player.77.5 AmpHeadlamp - RH.87.5 AmpHeadlamp - LH.97.5 AmpHeadlamp - RH.107.5 AmpHeadlamp - LH.115 AmpIn-line resistor, Front side lamp - LH, Front siderepeater - LH, Trailer pick-up, Rear number plate lamp -LH, Tail lamp - LH, Rear side marker lamp - LH,Illumination relay, Instrument illumination dimmer, &Radio cassette player.125 AmpFront side lamp - RH, Front side marker lamp - RH,Rear side marker lamp - RH, Tail lamp - RH, Trailerpick-up, & Instrument pack.1320 AmpNot used.1420 AmpNot used.1530 Amp.Blower relay.1620 Amp.Air conditioning compressor clutch relay, & Condenserfan relay.1715 AmpEngine immobilisation ECU, Blower relay, Airconditioning compressor clutch relay, Rear wiper relay,Rear wiper switch, Rear screen wiper motor, Rearwasher switch, Brake pedal switch, Hazard warningswitch, & Illumination relay.1815 AmpRough road detection ECU, Front wiper relay,Windscreen wiper motor, Wash wipe switch - frontscreen, Auto transmission inhibitor/reverse light switch,Brake pedal switch, & Interlock relay.1920 AmpCigar lighter - front.2020 AmpEngine management relay module, HO2S sensors, &Ignition coils. 
						

							CIRCUIT OPERATION
DEFENDER 90 NASREV: 9/971ENGINE IMMOBILIZATION (CODING) 
DESCRIPTION  
The vehicle engine immobilization (coding) is not detectable to the customer under
normal operating circumstances.  If the code of the engine immobilization unit does not
match the code of the ECM, when power is supplied to both units, the engine will be
immobilized.  In practice this should only happen if the ECM or engine immobilization
unit are renewed without reprogramming the ECM using TestBook.  
OPERATION   
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through fusible link 1 and fusible link 5 of
the engine compartment fuse box which are connected in series. Fusible link 5 (C570-2)
is connected to the ignition switch (C28-1) by the brown wire.  
With the ignition switch in position II, power flows through the switch (C94-1) to fuse
17 of  the passenger compartment fuse box (C581-13).  Fuse 17 (C581-14) is connected
to the engine immobilization unit (C61-10) by the green wire.  
With a 12 volt feed applied to the engine immobilization unit (C61-10), a coded signal is
sent from the immobilization unit (C61-15) to the ECM (C636-26) on the black wire. If
the coded signal from the immobilization unit does not match the signal expected by the
ECM, the ECM immobilizes the engine and does not supply a ground signal (C634-22) to
the immobilization control unit (C61-11), or the Malfunction Indicator Lamp (MIL)
(C233-10) on the red/slate wire. The MIL lamp will not operate if the ECM is
immobilized. The immobilization unit inhibits the starter relay and the engine will not
crank unless the key is held in the crank position for more than 5 seconds. The engine will
then crank, but will not start as the fuelling will still be inhibited by the ECM.
Fuse 3 of the engine compartment fuse box (C571-1) provides the engine immobilization
unit (C61-25) with a permanent 12 volt supply on the purple wire.  
The engine immobilization unit (C57-10) is connected to the starter inhibit/reverse light
switch (C69-4) by the black/orange wire.  
The engine immobilization unit (C61-17) is connected to the diagnostic socket (C40-8) by
the orange/light green wire.  
						

							CIRCUIT OPERATION
2DEFENDER 90 NASSTARTING AND CHARGING  
CHARGING - DESCRIPTION  
The charging system consists of a generator containing a rectifier pack and regulator to
maintain a constant direct current (d.c.) voltage in the system.  The generator is belt
driven from the crankshaft and cooled by a fan mounted behind the pulley.  The generator
has a fixed coil wound stator in which a field coil rotor rotates. Slip rings conduct current
to and from the field coils via 2 carbon brushes.  The regulator senses output voltage and
controls this to 14 volts.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through fusible link 1 and fusible link 5 of
the engine compartment fuse box which are connected in series. Fusible link 5 (C570-2)
is connected to the ignition switch  (C28-1) by the brown wire.  
With the ignition switch in position II, a current flows from the ignition switch (C94-1) to
fuse 1 of the passenger compartment fuse box (C580-1) on the white wire.  Fuse 1 feeds
the instrument pack ignition/no charge warning light (C230-4) on the white/green wire.
The warning light (C230-5) is grounded via the diode (C116-1) on the yellow/brown wire
and through the generator field windings (C185-1) on the brown/yellow wire.  The flow
of current through the warning light and field windings partially magnetizes the rotor. A
resistor (C37 & C38) is wired in parallel with the warning light to ensure continued
exciter voltage in the event of bulb failure. When the engine starts, the magnetized rotor
rotates within the stator windings, generating a 3 phase alternating current (a.c.) and
voltage which rises rapidly with rotor speed.  The field diodes convert the alternating
current to direct current and the generated voltage is fed back to the field windings.  As
the feed back voltage increases, the magnetic influence of the rotor also increases,
resulting in self-excitation of the rotor.  Generated current and voltage increases with
rotor speed until the generator is fully excited.  
When the generator outputs a voltage equal to that supplied by the battery, the ignition/no
charge warning light is extinguished as the potential difference across the light is 0 volts.
The diode between the generator and warning light prevents reverse flow through the
light.  The regulator functions as an electronic control switch on the ground side of the
field coils.  The regulator rapidly switches the ground circuit off and on to control the
generated voltage and current to safe limits.  
If the battery is in a low state of charge or current draw from the electrical system is high
and causes a voltage drop, the generator charges at its maximum rate until 14 volts is
generated. As battery voltage rises, the generator current output reduces.  
						

							CIRCUIT OPERATION
DEFENDER 90 NAS3STARTING - OPERATION  
When the ignition switch is in position II, power flows across the switch to fuse 20 of the
passenger compartment fuse box (C581-13) on the white wire.  Fuse 20 (C581-20) is
connected to the fuel pump relay winding in the ECM relay module (C154-2) by the
white/green wire.  The fuel pump relay winding (C154-1) is grounded through the  ECM
(C634-24) on the blue/purple wire.  The ECM grounds the fuel pump relay winding for a
short time when the ignition is switched to position II, and continuously during cranking
and while the engine in running.  With the fuel pump relay winding energized, the fuel
pump relay closes and power from fuse 6 (C575-2) of the engine compartment fuse box
flows through the fuel pump relay (C157-7) on the purple/white wire. The fuel pump relay
(C157-4) is connected to the inertia switch (C123-3) by the white/purple wire.  Assuming
the inertia switch is closed, power flows across the switch (C123-1) to the fuel pump
(C113-4) on the white/purple wire.  The fuel pump is grounded on a black wire.  
Turning the ignition switch to the crank position III, allows power to flow across the
switch (C90-1) to the starter relay winding (C151-85) on the white/red wire. The starter
relay winding is grounded  on the black/yellow wire to the starter inhibitor/reverse switch
(C69-5).  With the gear selector lever in park or neutral, the route to ground is from the
inhibitor switch (C69-4) to the immobilization unit (C57-10) on the black/orange wire.
Assuming the engine has been mobilized, the immobilization unit is grounded on a black
wire.  With the starter relay energized, power from fusible link 5 of the engine
compartment fuse box (C570-2) flows across the relay (C151-87) on the brown wire.
The starter relay is connected to the starter motor solenoid (C179-1) by the brown/red
wire.  The starter motor solenoid is grounded through the starter motor fixing.   With the
starter motor solenoid energized, feed from the battery is connected to the starter motor
(C178-1) through the starter solenoid on a red wire.  
						

							CIRCUIT OPERATION
4DEFENDER 90 NASGENERIC ENGINE MANAGEMENT SYSTEM (GEMS)   
DESCRIPTION  
GEMS is the engine management system utilized by the vehicle to control both electronic
ignition and fuel injection systems. It is able to alter ignition and fuelling settings to
ensure that the engine is operating at its optimum performance for the prevailing
conditions.  The ECM receives signals from sensors located around the engine and uses
the data to control the fuel quantity, fuel injection timing and ignition timing in order to
achieve optimum combustion of the fuel mixture in each cylinder.  
The main features of the system are as follows: 
· A single engine control module (ECM) controls the fuel injection system and
ignition system.  The ECM incorporates short circuit protection and can store
intermittent faults on certain inputs.  TestBook can be used to interrogate the ECM
for the stored fault codes. 
· Fuel is injected sequentially. That is, when the relevant piston is on the intake stroke
and the intake valve is open.
·  The ECM is electronically coded and prevents the engine being started unless it
receives the correct code from the engine immobilization ECU. 
· Detection and correction of engine knock on individual cylinders. The ignition
timing of each cylinder can be varied independently to the other cylinders and
ensures that knock on one cylinder is eliminated without a detrimental effect on the
ignition timing of the other cylinders. 
· A diagnostic connector, located below the passenger compartment fuse box, allows
engine tuning or fault diagnosis to be carried out using TestBook. 
· If certain inputs to the ECM fail, a back-up facility enables the engine to continue
running, although at a reduced level of performance.  
IGNITION SYSTEM  
The ignition system utilizes a direct ignition system (DIS) negating the need for a
distributor.  The system comprises 4 double ended coils operating the wasted spark
principle.  The circuit to each coil is controlled by the ECM. When a coil fires, a spark is
produced in two cylinders, however, as the resistance is higher in the cylinder on the
compression stroke, more spark energy is dissipated in this cylinder.