instrument panel JAGUAR XJ6 1994 2.G Electrical Diagnostic Manual

Automatic Transmission (V12) ~ Pow. rtrain
Engine
Torque Reduction and Malfunction Indication
This signal, to the ECM, has three modes of operation.
1. To indicate normal engine operation to the ECM.
2. During gearshifts, to request reduction of engine torque
3. During fault conditions, to inform the ECM.
During normal operation
theTCM outputs a constant duty cycle signal to the ECM. The signal is changed when torque
reduction is required to indicate to the ECM the degree of ignition retardation necessary. If a fault condition, relating
to OBD
II CARB legislation, occurs the TCM will transmit a signal to the ECM relating this event. The ECM will only
respond to this signal if its duration is 100 milli-seconds or longer.
If the signal from the torque reduction line is either HIGH or LOW for 2 or more seconds the EMS will recognise that
a fault may be present and transmit this information to the TCM.
If the signal from the torque reduction line lasts for 2 or more seconds the EMS will return to normal operation.
Sport Mode Indicator Lamp
The sport mode indicator lamp, mounted on the instrument panel, is illuminate when sport mode is selected and the
ignition switch is ON. Sport mode is selected at a two position switch mounted to the rear of the gear selector assembly.
Gearbox Failure Warning Lamp
The gearbox failure warning lamp, mounted on the instrument panel, is illuminated when afault is detected bytheTCM within the transmission electrical or mechanical systems.
Vehicle Speed (12 cylinder vehicles only)
This output signal is calculated from the transmission output speed and supplied to the ECM as an indication of vehicle
speed.
8.2.5 DIAGNOSTIC LINKS
Diagnostic
L line
One of a two wire interface used to activate stored diagnostic codes for reading by external equipment.
Diagnostic K Line
One of a two-wire interface used to communicate stored diagnostic codes for reading by external diagnostic equip- ment.
X300 EDM 7 Issue 1 August 1994

Brakes
12.2 SYSTEM DESCRIPTION
The anti-lock braking system (ABS) and traction control system CTC) comprise the following components:
0 Hydraulic module: incorporating a pump, motor, low pressure accumulator, valve block, and either an ABS Con-
trol Module (ABS CM) or an ABS / TC Control Module (ABS / TC CM).
U!&: Within the hydraulic module are contained the electro-hydraulic inlet and outlet valves which regulate brake
system pressure.
o Four wheel speed sensors; hub end mounted.
0 Three warning indicators plus a Brake Warning Lamp and a Traction OFF / ON switch; fascia mounted.
0 Throttle valve flap positioning mechanism; mounted adjacent to the hydraulic module.
0 Various auxiliary inputs; providing information to ABS / TC CM.
0 Diagnostic IS0 communication BUS input / output link.
The solenoid operated hydraulic valves
are activated by signals, from the ABS /TC CM, which are generated using in-
formation received from the wheel speed sensors.
For vehicles without traction control thevalves operate on threecircuits, two front and one rear, as necessaryto prevent
wheel locking during braking. Brake pressure is modulated individually
at the front wheels and collectively at the rear.
Rear wheel control operates
a 'select low' principle such that locking in either wheel is sensed, and controlled brake
pressure is applied to both wheels.
Vehicles with traction control fitted have
all four wheels individually controlled allowing selective regulation of tractive
and braking force to each wheel as necessary when traction control is in operation.
The ABS
/ TC system as a whole is monitored constantly by the ABS / TC CM and is disabled (switched off until fault
is rectified) automatically when certain failures are identified. In the event of
a failure being detected the ABS and TC
MIL lamps, located on the instrument panel will illuminate. Full boosted brake operation and normal acceleration con- trol is available when ABS /TC is disabled. The system will be disabled when the following conditions occur:
0 Valve failure.
0 Sensor failure.
0 Main driver failure (internal ABS / TC CM fault).
0 Redundancy error (internal ABS / TC CM fault).
0 Over-voltage.
0 Pump motor failure.
0 Throttle valve actuator motor failure.
In the event
of under-voltage both ABS and TC will be disabled and the ABS andTC MIL lamps on the instrument panel
will illuminate.
U!&: The TC MIL lamp will only illuminate providing a voltage is still present at pin 15 'IGN FEED'
Throttle potentiometer failure will disable the TC function only and illuminate the TC MIL lamp.
The
moduleABS/TC CM is activated when ignition is ON, after an initiation period of approximately 1.7 seconds. After
this time delay the control module is ready to process signals provided from the various input sources and, using the
software defined algorithm, control the electrical and hydraulic circuits.
The inductive sensors attached to each of the four wheels provide speed signals to the ABS
/ TC CM. These signals are processed by ABS/TC CM giving comparison between individual wheel speeds, controlling braking or traction as
necessary and generating a pulse to drive the speedometer. Each sensor is monitored for open and short circuit failure,
causing disabling of ABS / TC on detection of a fault condition.
Issue 1 August 1994 2 X300 EDM

Climate Control Systems
28-
I llSA I
1.
2.
3.
4.
5.
6.
7.
8.
9.
IO.
11. 12.
13.
14.
15.
21J 20
Instrument pack
Fascia switch pack
Defrost servo.
Air distribution box Solar sensor
Control panel
Centre console
LH blower motor
Water valve
Circulation pump
Coolant temperature sensor
LH front fuse
-box
Circulation pump relay
Ambient temperature sensor
A
/ C compressor
17
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27. 28.
29.
16 1's J86 1767
Compressor clutch relay
Trinary pressure switch
Radiator fan pressure switch
Control module
RH blower motor
Engine control module
Motorized
in-car aspirator
A
/ C isolate relay
RH blower motor high speed relay RH blower motor relay
LH blower motor high speed relay
LH blower motor relay
-
-
Fig. 1 Component Location Diagram
Issue 1 August 1994 2 X300 EDM

E I ect r ica I
15.1 SUPPLEMENTAL RESTRAINT SYSTEM
15.1.1 System Description
The Supplemental Restraint System (SRS) installation comprises:
0 electronic Diagnostic Module (DM)
0 driver and passenger-side air bag modules (including firing mechanisms)
0 two front impact sensors (left and right)
0 one safing sensor
0 dedicated wiring harness
0 two cable reel cassettes (integral part of the steering column harness)
0 Malfunction Indicator Lamp (MIL) and driver information message
The system is designed to provide protection for both driver and front seat passenger by automatically deploying air
bags in the event of a collision during forward travel. The driver
-side air bag is located in the centre of the steering
wheel assembly and the passenger-side air bag in the fascia panel.
In the event of a collision the impact
/ safing sensors operate, completing the electrical firing circuit and causing the
air bags to inflate within 32 milliseconds. At least two of the three sensors (at least one impact, and the safing sensor)
.must be activated to initiate firing. System operation is dependent upon battery voltage supplied directly, and via the
ignition switch, to the DM and the correct installation and operation of all system components, including the wiring
harness. Faults in system components, installation or wiring will be indicated by the MIL Lamp, located on the instru
- ment panel, which will illuminate 'SRS AIR BAG'. Indication is also given by the driver information message'AIR BAG'
displayed on the LCD panel below the speedometer.
15.1.2.1 Diagnostic Module (Fig. I)
The Diagnostic Module (DM), mounted below the passenger-side air bag module, behind the console fascia panel, is
the electronic microprocessor unit which monitors the whole SRS system. The state of the three system sensors, two
air bag modules and the wiring harness is monitored constantly to detect activation criteria and component faults.
15.1.2 COMPONENT DESCRIPTIONS
The unit also confirms correct supply conditions by compar- ing a direct battery voltage input with an input, via the igni- tion switch, of the same voltage value. Detection of system
faults will be relayed by the DM to the instrument panel and
the air bag MIL Lamp illuminated.
The DM contains a reserve power supply unit, enabling the
air bagsto fire even if supply voltage is lost during an impact
situation. The reserve power charge will be retained for ap
- proximately one minute after the positive supply voltage is
disconnected. An auxiliary internal circuit, known as the
'dwell enhancer', provides a temporary ground to compen
- sate for damaged primary crash sensors. If either primary
crash sensor operates for 5 milliseconds the 'dwell en- hancer' circuit will turn on, completing the firing circuit to
ground for 90 milliseconds. The purpose of this is to allow
air bag deployment even if the operated primary crash sen- sor circuit is defective or opens.
15.1.2.2 Wiring Harness
Fig. 1
A dedicated wiring harness, covered with yellow sheathing, independent of any other vehicle system, is used to electri- cally connect all the component items. To allow movement of the steering mechanism, two cable reel cassettes are
incorporated into the driver-side air bag module circuitry, as a means of compensating for steering wheel rotation is
required to prevent harness damage or disconnection. The two cable reel cassettes form an interface between the
steering column and air bag module and, due to their coiled construction, are able to contract or expand as required.
15.1.2.3 Air Bag Modules
The two air bag modules, driver and passenger side, are
each activated when either front impact sensor (Fig. 2) and
the safing sensor operate simultaneously. Both modules
contain a charge of sodium
azide/copper oxide which, when
ignited by an electrical impulse, generate a volume of ni
- trogen gassufficientto inflatetheair bag. Theamountof gas
generated is greater in the passenger-side air bag due to its
larger size. Both modules, including surrounding trim pan- els, are non-serviceable and once activated must be re-
newed as a complete assembly.
Fig. 2
X300 EDM 15.1 - 1 Issue 1 August 1994

E I ect r ica I rl
Electrical schematic - No Air Bag MIL Lamp
0
+12v
1. Instrument Panel Fuse 2. Engine Compartment Fuse 3. Safing Sensor
4. Cable Reel Cassettes
5. Driver-side Air Bag
Fig.
1
J86-1663
6. Passenger-side Air Bag 7. RH Impact Sensor 8. LH Impact Sensor
9. Air Bag MIL Lamp
10. Diagnostic Module
X300 EDM 15.1 -7 ~~ Issue 1 August 1994

Electrical schematic - Continuous Air Bag MIL Lamp Illumination
0
J86-16&
1. Instrument Panel Fuse
2. Engine Compartment Fuse 3. Safing Sensor 4. Cable Reel Cassettes
5. Driver-side Air Bag
Fig.
1
6. Passenger-side Air Bag
7. RH Impact Sensor 8. LH Impact Sensor 9. Air Bag MIL Lamp
10. Diagnostic Module
X300 EDM 15.1 -9 Issue 1 August 1994

Electricalschematic - Fault Code 12
0
a
e
+12v
1 p=-+-
rn 4 rn
-
P15 !J23 P16
P12
P13
PO3 I
10
1. Instrument Panel Fuse 6. Passenger-side Air Bag 2. Engine Compartment Fuse 7. RH Impact Sensor 3. Safing Sensor 8. LH Impact Sensor
4. Cable Reel Cassettes 9. Air Bag MIL Lamp
5. Driver-side Air Bag 10. Diagnostic Module
Fig. 1
J86-1665
X300 EDM 15.1 - 11 Issue 1 August 1994

E I ect r ical n
-
Electrical schematic - Fault Code 13
0
0
0
+12v
+12v
I_i
I 10
4
1. Instrument Panel Fuse 6. Passenger-side Air Bag
2. Engine Compartment Fuse 7. RH Impact Sensor
3. Safing Sensor 8. LH Impact Sensor
4. Cable Reel Cassettes 9. Air Bag MIL Lamp 5. Driver-side Air Bag 10. Diagnostic Module
Fig. 1
586-1668
X300 EDM 15.1 - 13 Issue 1 August 1994

Electrical rl
Electrkal schematic - Fault Code 14
0
0
0
0
J86-1667
1. Instrument Panel Fuse 6. Passenger-side Air Bag
2. Engine Compartment Fuse 7. RH Impact Sensor 3. Safing Sensor 8. LH Impact Sensor 4. Cable Reel Cassettes 9. Air Bag MIL Lamp
5. Driver-side Air Bag 10. Diagnostic Module
Fig. 1
X300 EDM 15.1 - 15 ~~ Issue 1 August 1994

E I ect r ica I rl
Electrkal schematic - Fault Code 2 1
0
0
0
0
2 P15 P23 PI 6
i I
10
1. Instrument Panel Fuse 6. Passenger-side Air Bag 2. Engine Compartment Fuse 7. RH Impact Sensor
3. Safing Sensor 8. LH Impact Sensor 4. Cable Reel Cassettes 9. Air Bag MIL Lamp
5. Driver-side Air Bag 10. Diagnostic Module
Fig. 1
J86-1668
X300 EDM 15.1 - 17 Issue 1 August 1994