1998 JAGUAR X308 engine

Input speed is monitored by the TCM with a rationality check being made against output speed. A fault will be flagged if the
indicated input speed exceeds 7400 rpm. Additionally, a failure judgement will be made if the indicated input speed is <160
rpm with engine speed >608 rpm and output speed >224 rpm
The procedure is similar for the output sp eed diagnostic. A fault (non OBDII) will be flagged if the indicated input speed
exceeds 6712 rpm. Additionally a failure judgement will be ma de if the indicated output speed is <160 rpm and the average
road wheel speed exceeds 100 rpm.
Under normal circumstance s after the output speed diagnost ic fault code has been set, the TCM uses rear wheel speed
information to compute its calculations, this has no effect on transmission operation. However, should a second fault occur,
in the ABS system, thus making rear wheel speed information unavailable, an additional fault code will be logged.
Control Systems
Introduction
Gear selection is achieved by controlling the flow of transmission fluid to internal multi-disc clutches.
The three solenoid valves direct the transmission fluid flow to the selected clutches and the pressure regulators control the
fluid pressure to each component. One pr essure regulator serves as a master pressure control for the entire system and a
second is used exclusively for torque converter clutch lock-up operation.
The TCM controls the internal components thus determining gear selection and shift pattern.
In the event of an electronic system fault the basic function s Park, Reverse Neutral and Drive Fourth are retained by the
hydraulic system.
Transmission Control Module (TCM)

The TCM is located in the same housing as th e ECM and is accessed in the same manner.
The TCM performs several 'self check' procedur es to ensure correct operation. It is possible due to the nature of these faults
that the module will fail to communicate with other nodes. However, condemnation of the TCM should not take place until
any CAN or power supply related problems have been resolved.
There are three self check procedures for the TCM. 1. 1. Check on ROM by calculatin
g a checksum and comparing this with a known stored value.

2.2. Check on non-volatile diagnostic memory by wr iting a test pattern and then reading it back.
3. 3. Internal 'watchdog' hardware to check whether the TCM has crashed.
Transmission Control Module Supply Voltage
The TCM monitors battery and igni tion switched supply voltages.
A permanent supply is used to maintain a battery backed 'memor y'. Should this supply be cut, due to battery disconnection
perhaps, the 'adaptive shift' valu es will be lost. This will result in a small reduction in shift quality for a period until th e
adaptions are 're-learned'
The TCM will adopt 'limp home' mode as a result of the supply voltage being >16V or <7V with an engine speed >1600
rpm.
Should the ignition supply be >7V but <9V the TCM will hold the gear that it has currently selected. If after 2.5 seconds,
with the engine speed >1600 rpm, the voltage remains at this level, 'limp home' mode will be adopted. The 2.5 second
delay is built in to prevent reaction to a momentary voltage fluctuation.
Operation
CAUTION: Disconnection of the TCM and / or the vehicle batt ery will cause system adaptions to be lost; this may be
apparent by shift quality degradation. Fo llowing reconnection, a period of 'varied' driving will reinstate adaptions and thus
normal operation. Please ensure that the customer is made aware that the adaption period is variable and may occur after
handover, as the transmission re-learns the prevailing driving style.
• NOTE: Should the TCM fail, please ensure that the control housing cooling fan is operating correctly. Failure of the cooling
fan MUST be rectified before renewing the TCM and details of a fan fa ilure should accompany the returned TCM.
The TCM processes information received in both analogue and digital form, such as:
Transmission input speed Transmission output speed Throttle position Pedal demand Gear selector position Engine torque Engine speed Transmission oil temperature Mode switch
This information is then used by the TC M to control shift energy management and decide which shift program to implement
and which gear to select.
The TCM uses the various sensors and inpu ts to monitor the correct operation of the system an d is programmed to take
default action and inform the operator when a fault occurs.
Safety Functions
The safety functions are designed to safeguard against inappr opriate actions by the operator as well as against system
malfunctions. The system prevents reve rse gear from being engaged at high forward speeds and prevents manual
downshifting at excessive engine speeds; these functions are not operational in mechanical limp-home mode.
The TCM constantly monitors the transmissi on for faults. In the event of a problem the TCM will adopt a 'limp home' mode
in which only P R N D - (selector in D but only fourth gear is enabled) are available. The operator will be made aware of
certain faults by an in strument panel warning.
The electrical and diagnostic system has been designed such that system integrity is protected at all times, the safety
concept being based on th e following three points:

1.1. The hydraulic system has 'fail-safe' characteristics regardin g its electrical operation, such that should the power
supply be lost to the electro-hydraulic actuators the transmission will initiate a limp-home mode.
2. 2. Recognition of critical shift operation by monitoring the last element in the signal path, ie the solenoid valve, and
checking by means of redundant me asured variables, ie engine speed, input speed and output speed.
3. 3. Each time the vehicle is started there is a check on the entire safety hardware and the associated program parts
and signal paths. A malfunction in this part of the system, or triggering of the safety circuit, is communicated to
the operator through the illumination of the transmission warning lamp.
TCM Inputs
Input Speed Sensor (Torque Converter Turbine)
The input speed sensor provides the TCM with transmission inpu t shaft speed information. This signal is produced from an
inductive pick-up, generating 30 pulses per revolution.
Transmission Output Speed Sensor
The output speed sensor provides the TCM with transmission ou tput shaft speed information. This signal is produced from
an inductive pick-up, generati ng 36 pulses per revolution.
Transmission Oil Temperature Sensor
A thermistor which provides an electrical indication of the oi l temperature to the TCM. The signal is measured as a voltage
with reference to analog ue ground in the TCM.
Kickdown Switch (where fitted)
Kickdown is intended to provide maximum vehicle acceleration , via the appropriate downshift(s), when the operator uses
full throttle. A kickdown switch provides an electrical signal to the TCM wh en the accelerator pedal is fully pressed. The
switch is normally open, connected to vehicle ground. Should the switch fail the TCM will detect kickdown using the
accelerator pedal position.
Throttle Pedal Stop (where fitted)
This component, used where the kickdown switch is not fitted, limits throttle pedal travel .in the same way. The kickdown
feature is retained, but is controlled by throttle position only. The pedal stop must be set, using the PDU, in the same way
as the kickdown switch to optimize performance.
Mode Selection Switch
The mode selection switch is a two position switch indicati ng to the TCM the current performance mode selected by the
driver. The switch generates a tw o-bit digital input to the TCM.
Rotary Position Switch
The rotary position switch detects the position of the transmis sion selector shaft. The switch is supplied as part of a new
transmission assembly, mounted on the transmission body. The swit ch is used to indicate to the TCM the six positions of the shaft: Park, Reverse, Neutral, Drive, Third and Second. The switch provides a four-bit input to the TCM.
Drive to Fourth Switch
Detects the movement of the selector lever from Drive to Fourth position. The selector cable, and therefore the transmission selector shaft, does not move as the lever is operated between these two positions. The switch is located within the 'J-gate'
assembly, producing a digital output to indicate to the TCM that the lever has moved from D to 4 .
Serial Communications Interfaces

Controller Area Network (CAN)
The TCM is an integral part of the CAN system which facilitates the interchange of real-time data between control modules
and sensors. Please see section 303- 14 for a full description of CAN.
OBDII Interface
Data concerning OBDII related transmission failures is stored in the ECM for access via the J1962 socket.
System Functions
Range Selection
The selector lever is connected to the transmission via a bowden cable, which operates the transmission selector shaft
between all positions except Drive to 4 .
The TCM detects the gear selected by means of a rotary position switch fitted to the transmission selector shaft. A separate
Drive to 4 switch is located within the 'J' gate' assembly.
Movement of the selector lever between Park, Reverse, Neutral and Drive manually directs th e flow of transmission oil; the
TCM having control of the forward gears selected while the lever is in the Drive position.
Shift Point Selection
The gearshift points are selected, by the TCM, as a function of the output speed, engine load, selector position and shift
program selected. The operator has control over the shift points via the selector lever, throttle pedal movement, kickdown
function and mode switch.
'J' Gate Layout

Mode Switch
This switch allows the driver to select one of two base shift maps; Normal and Sport modes, the switch being illuminated
when Sport is selected.
Special Shift Programs
These specific condition shift maps are available to enhance the operation of the vehicle under specific driving conditions.
and are listed below in order of priority / title and operating condition.
1. 1. Traction: When traction intervention is active
2. 2. Hot mode: Extreme engine / transmission temperatures

3.3. Gradient: Under specific speeds and loads
4. 4. Cruise: During cruise control
5. 5. Manual: Shift map when the LH side of the 'J gate' is used
Three specific condition shift maps have a higher priority than the two base shift maps and will intervene when appropriate
conditions prevail for traction, gradient or cruise.
When traction control (engine or brake system derived) is operational the TCM will implement the traction map to maximise
control of wheel slip.
The gradient maps are intended to enhance vehicle drivability when towing or climbing a gradient. The TCM will implement
the maps when increased driving resistan ce is detected and enhanced drivability, cooling and increa sed performance is
appropriate.
The cruise map is intended to minimize unwanted gearshifts and 'hunting' and is activated when cruising near to the set
speed, or resuming.
Connector Pins Identification
Connector Pin Identity Chart for EM007

Pin NumberCircuit Function
001Pressure regulator 2
002Mode switch status
003Not used
004Pressure regulator #4
005Pressure regulator #1
006Power ground
007Not used
008Rotary switch L2
009Rotary switch L4
010 to 011Not used
012Mode switch Pin B (Sport)
013D to 4 switch
014Input speed sensor (-)
015Output speed sensor (screen)
016Output speed sensor (+)
017Not used
018Kickdown switch (where used)
019 to 020Not used
021Analogue ground
022Fluid temperature sensor
023Input speed sensor (screen)
024 to 025Not used
026B+
027Not used
028Digital ground
029Pressure regulator #3

Automatic Transmission/Transaxle - 4.0L NA V8 - AJ27/3.2L NA V8 - AJ26
- Diagnostic Strategy
Diagnosis and Testing
Quick Reference Fault Chart
Quick Reference Fault Chart
Special Tool(s)

Digital multimeter

Generic scantool
SymptomPossible SourcesAction
Normal transmission
operation but fault codes
stored• NOTE: If P0706 is logged ignore P0742
Output speed sensor circuit fault
TCM faulty
ABS system fault (this code may log er roneously following an ABS problem)
Position switch and D to 4 switch circuit fault
P R 4 circuit fault

*
*
*
*
*
GO to
P0721 GO to
P1603 GO to
P0742
*
*
*
Sport mode will not selectMode switch circuit fault
*GO to
P0790
*
Mode switch state lamp not
workingMode switch supply
Mode switch circuit fault
*
*GO to
P0790
*
Poor, or reduced shift
qualityPresence of EMS faults
(may affect the accuracy of the torque signal)
*GO to EMS *
Transmission temperature sensor circuit
*GO to
P0710
*
Out of sequence shiftOutput / input speed sensor circuit fault
Mechanical fault (check all other operations)
*
*GO to
P1731
*
No torque converter lock-
upP R 4 circuit fault
*GO to
P0743
*
Mechanical fault, should P R 4 be OK
*GO to
P0741
*
Harsh shifts, engine stalling (torque converter stuck on)P R 4 circuit fault
Mechanical fault, should P R 4 be OK
*
*GO to
P0742
*
Default to 4th gearSolenoid / pressure regulator supply from TCM
*GO to
P0702
*
• NOTE: If the code logs wh
en 3rd is selected, then the D to 4 switch is the most probable cause If the code logs when D is selected fro m the LH side of the gate,
then check selector cable adjustment
'J gate' or selector ca ble out of adjustment
D to 4th switch
Rotary position switch circuit
*
*
*GO to
P0706
*
Input speed sensor circuit fault
Input speed sensor faulty
*
*GO to
P0715
*
Solenoid #1 circuit fault
*GO to
P0753
*
Solenoid #2 circuit fault
*GO to
*

DTC P1745 Pressure regulator 1 malfunctionHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent, loose or corroded
*
*
*
*GO to Pinpoint
Test D
*
DTC P1746 Pressure regulator 2 malfunctionHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint
Test D
*
DTC P1747 Pressure regulator 3 malfunctionHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint
Test D
*
DTC P0743 Torque converter clutch system
electricalHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint
Test D
*
DTC P1748 Pressure regulator 5 malfunctionHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint
Test D
*
DTC P0721 Output / turbine speed sensor circuit
malfunction• NOTE: This DTC is non OBDII but is included for
reference to P1720
Output speed sensor signal faulty
Harness fault
Connector pins(s) bent , loose or corroded
Damaged harness screen
*
*
*
*GO to Pinpoint
Test E
*
DTC P1720 Loss of output speed and wheel
speed informationAs P0721
ABS fault
*
*GO to Pinpoint
Test E
*
DTC P0715 Input / turbine speed sensor circuit
malfunctionInput speed sensor signal faulty
Harness fault
Connector pins(s) bent
, loose or corroded
Damaged harness screen
*
*
*
*GO to Pinpoint
Test F
*
DTC P1722 Stall speedOutput speed sensor signal faulty
Harness fault
Connector pins(s) bent
, loose or corroded
TCM failure
Transmission mechanical fault
*
*
*
*
*GO to Pinpoint
Test G
*
DTC P1726 Engine overspeed malfunctionTransmission mechanical fault
*GO to Pinpoint
Test H
*
DTC P1730 Gear control malfunction 2,3,5,Input speed sensor signal faulty
Output speed sensor signal faulty
Harness fault
Connector pins(s) bent
, loose or corroded
TCM failure
Transmission mechanical fault
*
*
*
*
*
*GO to Pinpoint
Test I
*
DTC P1734 Gear control malfunction 4Input speed sensor signal faulty
Output speed sensor signal faulty
Harness fault
Connector pins(s) bent
, loose or corroded
TCM failure
Transmission mechanical fault
*
*
*
*
*
*GO to Pinpoint
Test I
*
DTC P1779 Load control malfunctionInput speed sensor signal faulty
Output speed sensor signal faulty
Harness fault
Connector pins(s) bent
, loose or corroded
TCM failure
Transmission mechanical fault
*
*
*
*
*
*GO to Pinpoint
Test I
*
DTC P1603 EEPROM malfunctionSee Monitoring Procedure
*GO to Pinpoint
Test J
*
DTC P1605 TCM checksum failureSee Monitoring Procedure
*GO to Pinpoint
Test J
*
DTC P1608 Watchdog malfunctionSee Monitoring Procedure
*GO to Pinpoint
Test J
*
DTC P1793 Ignition supply malfunction >16 < 7
voltsBattery charging system fault
Harness fault
Connector loose or corroded
*
*
*GO to Pinpoint
Test K
*

Pinpoint test A: P0741, P0742, P0743
Pinpoint test B: P0743
Connector pin(s) bent or tracking between
connections
*
DTC P1789 Ignition supply malfunction >7 < 9
voltsBattery charging system fault
Blown fuse
Harness fault
Connector loose or corroded
Connector pin(s) bent or tracking between
connections Ground fault
*
*
*
*
*
*GO to Pinpoint
Test K
*
DTC P0710 Transmission fluid temperature
sensor malfunctionDamaged sensor
Sensor out of range / short
Harness open circuit
Harness short
Connector loose or corroded
*
*
*
*
*GO to Pinpoint
Test L
*
PINPOINT TEST A : P0741, P0742, P0743
TEST CONDITIONSDETAILS/RESULTS/ACTIONS
A1: RETRIEVE DTCS
• NOTE: Battery and or ECM disconnection prior to scanning wi
ll erase all data, ensure that the correct DTC is present.
Connect the scan tool 1
Have the DTC(s) and freeze frame data been recorded?
Yes GO to A2
A2: RENEW TORQUE CONVERTER
Renew the torque converter 1
Has the torque converter been renewed?
Yes GO to A3
A3: END
Drive the vehicle for a period from cold to include idle, brisk
acceleration and steady state cruising up to and including
normal engine temperature. Check for the presence of DTC. 1
Has the fault code cleared?
Yes STOP
No Contact Jaguar Service
PINPOINT TEST B : P0743
TEST CONDITIONSDETAILS/RESULTS/ACTIONS
B1: RETRIEVE DTCS
• NOTE: Battery and or ECM disconnection prior to scanning wi ll erase all data, ensure that the correct DTC is present