1994 JAGUAR XJ6 air condition

Automatic Transmission (AJ16)
TORQUE REDUCTION SIGNAL - P 1780
The diagnostic for this signal is based entirely on feedback from the ECM. If the torque reduction request is active for
greater than 2 seconds, the ECM starts the torque reduction fault timeout (IO seconds). If the signal returns to the
standby condition within this time, the timeout is reset. If the timeout matures then the ECM stores a fault code and
transmits 93% on the torque signal line and also lights the MIL where necessary.
The ECM will also initiate the torque reduction fault timeout
if the signal line is permanently high or low for greater
than 125ms. The conditions for resetting the timeout and the actions if the timeout matures are the same as previously
described above. When the TCM receives the correct indication on the torque signal line, this fault code will be stored
and
a substitute function will be adopted and the warning lamp will be illuminated. The engine management will send
normal torque signal when the torque reduction signal returns to standby or when the ignition is reset.
This torque reduction signal is used during gearshifts to conveythe actual amount of retard to be applied to the ignition
advance angle
afterthe other trims. The signal idles at 17% (or 12% if theTCM wishes to drive the MIL on), and changes
to 20% at the start of a gearshift. This represents 0" retard. When an amount of retard is required, the PWM will increase
to the desired value (between 20% and 90%) and return to 20% and then to idle state at the end of the shift.
TCM
PI HARNESS ECM
CC007/032 P1063/008 P1105/026
TORQUE SIGNAL MALFUNCTION - P 1781
The torque signal is a PWM signal from the ECM to the TCM which conveys information about the actual torque devel- oped by the engine in the range 0 to 510Nm. The base frequency is 91Hz and the signal which is active low should be
within the range 10% to 90% modulation. The torque signal is monitored continuously during initialization and oper
- ation. If the frequency of the signal is incorrect or the signal is out of range, then this fault code will be flagged. The
TCM will adopt a substitute function and the warning lamp will be illuminated. This fault code will only be flagged if the engine speed is above 448 rpm.
TCM
PI HARNESS ECM
CC007/02 1 P1063/007 PI 105/033
Possible causes:
. Faulty harness wiring I connector.
. Faulty signal from ECM.
Effects:
. Transmission warning lamp illuminated.
Substitute torque signal adopted by TCM.
. =Normal mode only available.
. No kickdown facility.
. Maximum fluid pressure applied.
Remedy:
. Repair or renew harness / connector.
Examine ECM fault diagnosis (refer to EDM, section 5.1).
Issue 1 August 1994 16 X300 EDM

Climate Control Systems
.-)
14.1 SYSTEM DESCRIPTION
The Air Conditioning electronic Control Module (A/ CCM) located on the right-hand side of the A / C unit, controls the 0 functions of the system.
These functions include:
0 In-car temperature control
0 In-car humidity control (Air conditioning vehicles only)
0 Air flow / volume and distribution
The temperature of the passenger compartment is continuously compared with the temperature selected on the con
- trol panel LCD. A digital microprocessor within the A/ CCM receives the data signals. Comparison of these signals
and those from system temperature sensors and feedback devices results in the appropriate output voltage changes
needed to vary the blend of air flow into the passenger compartment.
The climate control system peripherals communicate with the A/ CCM via three main device categories comprising
of manual inputs, automatic outputs and inputs, as shown
in Fig. 1.
Air Temperature Control I
9 Recirculation switch
. Air con on/off switch
System on/off switch
. Auto. / Man. select
Set temperature
. Air flow outlet mode set
Heated front screen switch
. Heated rear screen &
heated mirror switch
. External temp. display
switch
. FahrenheiVCentigrade switches
4
. Solar sensor
. Motorized in-car aspirator
. Ambient temp. sensor
. Evaporator temp. sensor
Heater matrix temp. sensor
. Compressor lock sensor
. Face differential temp. control
. Refrigerant pressure switch
. Engine speed signal
Engine coolant temperature
Vehicle speed signal
. Circulation pump
. Water valve
. Power transistor (fan speed
Servo motor potentiometers:
signal
control)
LH air inlet flap
RH air inlet flap
Centre vent flap
Foot flap
Defrost flap
Air by
-pass flap
Air Inlet Control
9 LH air inlet
. RH air inlet
CONTROL PANEL
1
A / CCM
I I
I . External temp. display I
. Coolant recirculation valve
. Coolant recirculation pump
LH blower motor & power transistor
. RH blower motor & power transistor
. LH high speed relay
Air Distribution Control
Servo motor for:
9 Centre vent flap
Foot flap
Defrost flap
Fig. 1 Schematic view A / CCM Inputs & Outputs
X300 EDM 1 Issue 1 August 1994

Climate Control Systems
System Differences
m:
Heater only vehicles do not have the following fitted:
This section applies generally to both air conditioning and heater systems. System specific descriptions, pro-
cedures, tests etc. are indicated.
0 Solar sensor
0 Clutch request and acknowledge circuitry.
0 Refrigerant pressure switch.
0 Control panel - deletion of air conditioning button.
6 cyl. engined vehicles do not have either the electrical load inhibit or the compressor lock sensor.
Heated Front Screen
(HFS) is optional on both air conditioning and heater panel versions.
14.2 COMPONENT DESCRIPTIONS
14.2.1 Control Panel
The control panel (Fig. 1) provides the operator interface with the climate control system.
The control panel communicates with the
A / CCM via a serial data communications link. During each data transfer
cycle the control panel states whether it is an air conditioning or heater version, thus enabling the A/ CCM to control
the system functions accordingly.
Tontrol panel operation is described in detail in the 'Climate Control Systems' section of the VSM.
-
Fig. 1 Control Panel (A / C with Heated front Screen)
J86 - I726
14.2.2 Control Panel Inputs /Outputs
Description I CableColor
I 1 I Output clock I Grey I
2 Output start Grey / Red
3 Input data
in Grey / Yellow
4 Output
data out Grey / Green
5 Output
ignition positive White / Red
6 Output auxiliary positive
White / Blue
7 Output
ground Black
8 Dimmer
Red
9 Dimmer override Red / Green
I 10 I Not connected I- I
I 11 I Not connected I- I
I 12 I Not connected l- I
X300 EDM 3 Issue 1 August 1994

Climate Control Systems
14.2.3 Solar Sensor (Fig. 1)
The solar sensor is mounted on top of the facia, between the
facia defrost grilles.
The sensor isconstructed around
a photo-diode to measure
direct sunlight. The sensor provides an output response sig-
nal totheA1CCM;thisensuresthe in-cartemperaturestabil- ity whilst reducing outlet temperature to compensate for
solar load heating. The solar sensor is fitted to aircondition- ing vehicles only.
14.2.4 Engine Speed Signal
The A 1 CCM receives an engine speed signal from the En- gine Control Module (ECM).
This signal facilitates compressor lock sensing (12 cyl. ve- hicles only).
This signal also aids the A
1 CCM inhibition of the heated
screen relays. At engine speeds lower than 800 RPM the A I CCM assumes poor idle or engine not running and will not
permit the selection of the heated screens.
14.2.5 Ambient Temperature Sensor (Fig. 2)
The ambient temperature sensor is located within the LH
brake cooling duct.
The sensor detects exterior airtemperature and provides the
A
I CCM with a signal to allow compensation for ambient
conditions.
The A
1 CCM is then capable of informing the control panel of the ambient air temperature in both Centigrade and
Fahrenheit, and updates the information every four
seconds.
The sensor is damped and
so does not detect temperature
fluctuations as quickly as other temperature sensors. This
facility prevents temporary temperature fluctuations affec
- ting overall temperature control.
14.2.6 Vehicle Speed Signal
The A 1 CCM receives a road speed signal from the instru- ment pack, derived from the ABS 1 TC CM.
This signal is required to control the blower fan speed to mi
- nimise the effects of ram air, i.e. blower fan speed changes
in proportion to vehicle road speed.
The signal also determines the frequency
at which the ambi- ent air temperature is updated. The road speed compensa-
tion for blower control is inhibited when the selected
temperature is 'LO (maximum cooling) and 'HI' (maximum
heating) and defrost mode.
14.2.7 Evaporator Temperature Sensor
Located next to the evaporator fins, the sensor detects the air temperature leaving the evaporator, and sends this sig- nal to the A 1 CCM.
When the temperature approaches
OOC, the A 1 CCM disen-
gages the compressor to prevent freezing conditions. When
thetemperature rises above3OC.theAlCCM re-engagesthe
compressor.
J82-L06 Fig. 1
Fig. 2
0
0
Issue 1 August 1994 4 X300 EDM

Climate Control Systems
14.2.8 Heater Matrix Temperature Sensor
This sensor is positioned inside the air conditioning unit just
downstream of the heater matrix. The sensor monitors the
post
-heater air temperature, before the air is distributed to
the passenger compartment. In conjunction with the A / CCM this sensor provides the input to maintain a constant
outlet temperature.
14.2.9 Coolant Temperature Signal
This input is required to provide blower inhibit control, to
avoid cold
air being delivered in heating mode when the en- gine coolant temperature is below 3OOC. The input also
monitors the temperature of the coolant delivered to the
heater matrix to assist outlet temperature control.
14.2. IO Compressor ON Signal
This signal line monitors the compressor relay to inform the
A/ CCM of the compressor status and to facilitate lock detec-
tion and error sensing.
14.2.11 Motorized In-car Aspirator (Fig. 1)
The Motorized In-car Aspirator (MIA) detects the air tem- perature within the passenger compartment. A small motor
driven fan (blown aspirator) draws air across the thermistor,
which changes its electrical resistances in response to
changes in air temperature, converting
a temperature rating
into an electrical signal.
The MIA is located on the back of the driver's side knee
bolster.
14.2.12 Compressor Lock Signal - 12 cy/. vehicles only
This signal provides the A / CCM with compressor rotation
speed. This is then compared with engine rotation speed.
If the ratio of the compressor speed against engine speed
drops belowthe A/CCM limits, indicating compressor/ belt
slippage, the compressor clutch is disengaged.
When compressor clutch disengaging commences the A/C
LED on the control panel will flash once per second.
14.2.13 Refrigerant Pressure Switch (A/C Vehicles only)
The refrigerant pressure switch (Fig. 2) is located under the
hood on the liquid line.
The switch contacts open when abnormal pressures are
sensed. This action inhibits the compressor clutch drive.
14.2.14 Water Valve
The water valve is used in conjunction with the water pump
to regulate the output air temperature. The water valve is off when the ignition is on, engine not running.
14.2.15 Water Pump
The water pump is energized in all engine running modes
except for under cold coolant condition at blower inhibit and
in panel
off mode. The water pump is off when the ignition
is on, engine not running.
If
J82-488
KI Fia. 1 I
Fia. 2
X300 EDM 5 Issue 1 August 1994

Climate Control Systems
14.2.16 Servo Motor Control
The system incorporates several servo motors which direct the flow of air through the air conditioning system. The
motors are driven by A / CCM signals in either a clockwise or anti-clockwise direction.
Servo motor position is monitored via
a feedback potentiometer situated within the motor housing.
The system servos comprise:
o RH and LH Air intake servos (Fresh / Recirc.).
0 Centre vent servo.
o Defrost (screen vent) servo.
0 Footservo.
0 Cool air by-pass servo.
14.2.17 Blower Motor Control
The A/ CCM controls two blower motors, delivering airflow
to the evaporator / heater unit, at variable fan speeds. The
blower motors are regulated by power transistor modules
which provide linear variation of blower speed; the blower
speed
is increased or reduced progressively in response to
vehicle speed, minimising the ram effect of forward motion.
The blower motors are inhibited when engine coolant tem
- perature is below 30°C and heating is requested.
14.2.18 Differential Control
The differential control is mounted on the facia centre vent. It is used to control the temperature difference between the
upper and lower outlets. Fig.
1 Servo
Motor
14.2.19 Heated Rear Window, Door Mirrors and Front Screen
The Heated Rear Window (HRW) function can only be activated with the ignition on and the engine running. Operation of the HRW switch operates the status condition LED on the control panel and switches on the HRWfor approximately 21 minutes. Selection of the HRW also operates the door mirror heaters for approximately 11 minutes. The operation
can be cancelled by switch re-selection or ignition off. System off does not cancel the HRW operation.
The Heated Front Screen
(HFS) function can only be activated with the ignition on and the engine running, and either
‘defrost’ mode selected or HFS selected. Each half, left and right hand split, switches on for approx. 6.5 minutes. The
operation can be cancelled by switch re-selection or ignition off. System off does not cancel the HFS operation.
0
0
Issue 1 August 1994 6 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

IT Electrical
15.1.2.4 Impact Sensors
The three impact sensor devices determine when air bag fir- ing is necessary by detecting crash conditions according to
direction of travel and force of movement. An impact of
sufficient force in a forward direction will close contacts in
either one or both of
the front impact sensors, left and right.
When either (or both) of the front sensors contacts are
closed then the impact force must be sufficient to close the
safing sensor contacts also, before air bag firing can com
- mence. The front impact sensors are mounted between
each headlamp mounting bracket and bonnet hinge mount- ing (Fig. 2, previous page), the safing sensor is mounted on
the right-hand side footwell at the base of the 'A' post (Fig.
1). Fig. 1
1.
Driver-side Air Bag Module 6. RH Impact Sensor
2. Cable Reel Cassette 7. Ground 3. Passenger-side Ait Bag Module 8. Rear Safing Sensor 4. Diagnostic Module 9. Cabin Harness Connector
5. LH Impact Sensor
Fig.
2 SRS System Schematic
Issue 1 August 1994 15.1 - 2 X300 EDM