1994 JAGUAR XJ6 service

Automatic Transmission (V12) Powertrain
8.2.3 OPERATING PRlNClPL ES
The electronic control system is split into four main functional areas:
0 Shift Point Control
0 Lock-up Control
0 Pressure Modulation
0 Engine Torque Control
0
Shift Point Control
The optimum gear ratio is selected as a function of transmission output speed, engine load, position of selector switch
and program switch.
Lock-up Control
The torque converter clutch is engaged as a function of load, output speed, gear selected and drive program. Lock-up
is possible in second, third and fourth gear. Apply and release quality is controlled by the pulse width modulated pres-
sure regulator solenoid.
Pressure Modulation
Hydraulic pressure in the transmission shift friction elements is accurately matched to transmission output torque
using an electrically operated solenoid valve to control pressure level. Transmission input torque is calculated from
an output torque value, supplied by EMS, and converter slip.
Engine Torque Control
Engine torque control reduces the energy dissipated within the system during gear shifts. The effect of this control
increase the transmission service life by reducing slippage time, increases comfort by reducing clutch torque trans- mission and allows a greater transfer of power by the transmission unit.
8.2.4 INPUTS / OUTPUTS
8.2.4.1 INPUTS
Transmission Range
The transmission range is detectec ,ythe pressureswitch manifold located within the transmission unit. The manifold
transmits a coded message to the TCM indicating gear selector position.
Performance Mode Select
Performance mode select uses a two wire input to the TCM allowing selection of different transmission operating
modes.
Line A; Used for selection of traction control shift pattern and controlled
by the ABS /TC CM.
Line
B; Used for selection of 'Normal' or 'Sports' mode, manually selected at a two position rocker switch mounted
on the gear selector unit. Switch resistance is equal to or greaterthan look$, open circuit and equal to or less than 0.5$ closed circuit, measured across contacts at a current of 10mA.
Kickdown Switch
This signal is controlled by the operation ofthe kickdown switch on depression of the accelerator pedal to its full extent.
The switch remains in 'normally open' position until contact with the pedal closes the contacts. Switch resistance is
equal to or greater than look$, open circuit, and equal to or less than 0.5$ closed circuit, measured across contacts at
a current of
10Ma.
Calibration Select
The calibration select input allows identification of different vehicle specifications, ie 4.0 liter supercharged, or 6.0 liter (V12). The link, to ground, from the TCM is either short or open circuit, dependant upon internal software calibration
for each vehicle variant.
X300 EDM 5 Issue 1 August 1994

Climate Control Systems
High speed operation at all times - RH blower
a Cause:
1. Faulty high speed relay.
2. Faulty harness wiring.
Remedy:
1. Check the relay contact is not stuck 'ON'.
2. Check continuity of wiring harness between blower motor pin 8 and ground, pin 10 and A / CCM pin 42 (16-way connector) and pin 13 and A/ CCM pin 41 (16-way connector).
High speed operation at all times - LH blower
Cause:
1. Faulty high speed relay.
2. Faulty harness wiring.
Remedy:
1. Check the relay contact is not stuck 'ON'.
2. Check continuity of wiring harness between blower motor pin 8 and ground, pin 10 and A / CCM pin 50
(16-way connector) and pin 13 and A / CCM pin 49 (16-way connector).
14.7.23 Water Valve
For mechanical diagnosis of the water valve, refer to section 14 of the Vehicle Service Manual.
The solenoid coil fitted to the water valve housing has
a resistance of 17.4Q f 1P at 5 - 35 "C.
Check the continuity between pin 2 water valve white 2-way multi-plug and the A/ CCM (pin 52,26-way connector).
Check for ground
at pin 1 water valve white 2-way multi-plug.
14.7.24 Wafer Pump
Disconnect the black 2-way connector.
The motor operation can be checked by applying battery voltage to pin 1, motor 2
-way connector, and ground to pin 2.
Inspect the harness for open circuit or short circuit to ground. Rectify as necessary. If no harness faults are apparent,
renew the
A / CCM.
CAUTION: If removed the water pump should not be operated dry, and for a maximum of five minutes when wet. Failing to observe this may result in pump rotor and shaft damage.
The application of reverse polarity voltage at pins 1 and 2 will result in damage to the pumps internal cir-
cuitry.
X300 EDM 25 Issue 1 August 1994

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

Electrical rl
15.1.3 AIR BAG DISARMING/ ARMING PROCEDURE
warnings and cautions
WARNING: DISARM SRS BEFORE SERVICING ANY SRS OR STEERING COLUMN COMPONENT.
ALLOW A MINIMUM OF ONE MINUTE TIME DELAY FOR THE BACK
-UP POWER SUPPLY TO DISCHARGE,
AFTER THE BATTERY GROUND LEAD HAS BEEN DISCONNECTED.
THE SYSTEM COMPONENTS ARE NON
-SERVICEABLE, IF FAULTS ARE SUSPECTED, CHANGE COMPO- NENTS FOR NEW ITEMS ONLY.
NEVER PROBE THE CONNECTORS OF AN AIR BAG MODULE.
FAILURE TO OBSERVE THE ABOVE PROCEDURES MAY RESULT
IN ACCIDENTAL DEPLOYMENT OF AIR
BAG.
ALWAYS WEAR SAFETY GLASSES WHEN WORKING ON AIR BAG EQUIPPED VEHICLES.
PERSONNEL CARRYING AN AIR BAG MODULE MUST ENSURE THAT THE MODULE AND TRIM COVER
ARE POINTED AWAY FROM THE BODY. WHEN POSITIONED ON A BENCH
OR WORK SURFACE ENSURE
THAT THE AIR BAG MODULE AND TRIM COVER FACE UPWARDS, LIMITING MOTION ON ACCIDENTAL
DEPLOYMENT.
ALWAYS WEAR GLOVES WHEN HANDLING DEPLOYED AIR BAG MODULE, DEPOSITS OF SODIUM HY
- DROXIDE MAY BE PRESENT ON THE MODULE SURFACE. IF SODIUM HYDROXIDE CONTACTS ANY
AREA OF SKIN, WASH THE AFFECTED AREA IMMEDIATELY WITH MILD SOAP AND WATER. DISPOSE OF
THE DEPLOYED AIR BAG USING THE CORRECT PROCEDURES, REFER TO SECTION
15 OF THE VSM.
CAUTION:
When scrapping vehicles ensure air bags have been deployed.
If
a component has been renewed and the fault does not clear, refit original item and repeat diagnostic
procedure.
After servicing repeat diagnostic procedures to ensure correct system operation.
Renew air bag module if surrounding trim panels are damaged.
Do not attempt to repaint trim covers as paint may damage cover material.
Disarming
. Allow a minimum 1 minute time delay before attempting to diagnose or renew any component in the SRS system.
Remove driver-side air bag module and connect air bag simulator to cable reel cassette multi-plug.
. Remove passenger-side air bag module and connect air bag simulator to harness.
. Re-connect battery ground lead.
Disconnect
the battery ground lead.
This delay allows the DM back
-up power supply to discharge, preventing accidental firing of the air bag.
0
Arming
Disconnect the battery ground lead.
. Remove air bag simulators and install driver and passenger-side air bag modules. Ensure fasteners are tightened
. Re-connect battery ground lead.
Switch ignition 'on' and ensure air bag MIL Lamp extinguishes.
to specified torque.
X300 EDM 15.1 -3 Issue 1 August 1994

Electrical n
15.1.4 DIAGNOSTICMODULE FAULT CODES
Fault codes can be extracted in one of two ways:
Through the
IS0 Communication Bus using Jaguar Diagnostic equipment.
As a series of flashes using the SRS Service Tool.
Each series offlashes represents a two digit number, representing the fault code. For example fault code
24 is displayed
as:
Two flashes, a one second pause, four flashes, three second pause. Then repeated.
All fault codes are listed in order of priority.