1994 JAGUAR XJ6 engine

Automatic Transmission (AJ16) w
8.1.1 ZF 4HP 24 E TRANSMISSION, SYSTEM DESCRIPTION
The electronic transmission system fitted to normally aspirated 4.0 liter vehicles comprises the following components:
0 ZF 4HP 24 E Automatic Transmission
0 Rotary selector switch
0 Electronic Transmission Control Module
0 Decoder Module
0 Performance Mode Switch
0 Kickdown Switch
0 Gear Selection Illumination Module
System control is effected by the transmission control module (TCM), located behind the passenger side fascia, which
continuously monitors requests made by the drivervia the gearselector, throttle pedal etc. This data is used
inconiunc- tion with the speed input from the transmission and inputs from the engine management system, to calculate optimum
shift points and control parametersfor shift pressure and ignition retardation to enhance shift quality and reduce trans-
mission unit wear.
TheTCM is also able to detect faults within the system and store the relevant fault codes for interrogation with diagnos-
tic equipment.
Gear shifts are controlled by three solenoid valves, and
a pressure control regulator, located on the valve block within
the transmission unit assembly. If a serious fault occurs, the TCM removes all electrical power from these valves and
the transmission system reverts to a mechanical default condition. This condition allows only mechanical selection
of reverse and one forward gear, either third or fourth, depending on prevailing conditions at the time of the default.
The decoder module receives inputs from the rotary switch and decodes these to drive one of six possible outputs,
illuminating the correct gear indicator on the gear selector illumination module.
The performance mode switch and kick
-down switch are used to adjust transmission operation as required by the
driver. Performance mode selection, made via a switch mounted on the gear selector mechanism surround, can be
either NORMAL, for everyday use, or SPORT, for enhanced performance. Kick
-down is activated by a switch mounted
below the accelerator pedal and is used to initiate a downward gear change, increasing torque and acceleration.
8.1.2 COMPONENT DESCRlPTIONS
Transmission Unit
The ZF 4HP 24 E automatic transmission unit houses the three solenoid valves which control gear shifts. A pressure
control valve is also located on the solenoid valve block. These four valves initiate and control shift patterns within
the transmission unit by regulating fluid flow.
Rotary Selector Switch
The seven position rotary gear selector switch is mounted on the LH side of the transmission unit and indicates gear
selection to the TCM and decoder module.
Transmission Control Module
The electronic transmission control module regulates gear changes by controlling the operation of the transmission
unit solenoid valves, and monitoring the state of other vehicle systems which have an effect on torque demand, vehicle
speed etc. The module also interfaces with the engine management system, climate control system, body processor
unit and ABS
I traction control system.
Connections from the TCM are listed on the following page.
X300 EDM 1 Issue 1 August 1994

Automatic Transmission (AJ16)
8.1.3 DIAGNOSTIC FAULT CODES
The following codes are stored within the TCM whenever a fault is detected on the system. The codes can be accessed
using Jaguar Diagnostic Equipment or a hand held, proprietary scan tool.
Code Description
MIL Indication Page No.
P 0603 Internal control module memory error MIL on 26
P 0605 Internal control module ROM test error
MIL on 26 I P 0702 Transmission control system electrical MIL on 5
P 0705 Transmission range sensor circuit malfunction MIL on 6
P 0706 Transmission range sensor circuit range / performance MIL on 6
8
8
P 0712 Transmission fluid temperature sensor low input -
P 0713 Transmission fluid temperature sensor high input -
P 0721 Output speed sensor circuit range / performance MIL on 10
P 0722 Output speed sensor circuit no signal MIL on 10
P 0726 MIL on 12
P 0727 1 Engine speed input circuit no signal MIL on 12
P 0743 Torque converter clutch system electrical MIL on 14
P 0748 Pressure control solenoid electrical MIL on 14
' Engine speed input circuit range / performance
P 0753 Shift solenoid A electrical MIL on 14
P 0758 Shift solenoid B electrical MIL on 14
P 1608 TCM watch-dog fault MIL on 26
P 1780 Torque reduction signal malfunction - 16
P 1781 Torque signal malfunction - 16
P 1782 Traction control input electrical - 18
P 1785 Transmission fault lamp malfunction - 20
P 1790 TP signal system range / performance MIL on 21
P 1791 TP electrical signal system MIL
on 21
P 1792 Sport mode indicator - 23
P 1794 System voltage malfunction MIL on 24
P 1796 Kickdown switch system - 24
t: Codes which do not cause the MIL to illuminate cannot be read by the hand-held scan tool as they are not SA€ P- generated.
I. Transmission Control Module (TCM)
2. Transmission Unit
3. TCM Multi-pin Connector
4. Transmission Rotary Switch
5. Transmission Connector Plug
6. Engine Control Module
7. Instrument Pack
8. ABS /Traction Control Control Module
9. Kickdown Switch
Issue 1 August 1994 4 X300 EDM

w Automatic Transmission (AJ16)
TRANSMISSION RANGE SENSOR - P 0705 / P 0706
The rotary switch is located on the LH side of the transmission. The harness incorporates the transmission wiring and
runs into the car through the a hole in the LH side of the tunnel. The connectors GBOOI and GB002 are located on the
side of the selector mechanism ‘J’ gate assembly.
TRANSMISSION RANGE SENSOR CIRCUIT - P 0705
This test is performed continuously by the background diagnostics during operation. The test is a plausibility check
on the 3 bit Gray code. The test criteria is that an invalid code must not be seen. If a Z code is seen for more than looms,
then this fault code will be stored and the transmission will adopt the default function.
TRANSMISSION RANGE SENSOR CIRCUIT RANGE/ PERFORMANCE - P 0706
This is a plausibilitycheck on the 3 bit Gray code which is only performed once during cranking when the engine speed
reaches
a specific threshold. If the gear is not P or N when this test is performed, then this fault code will be flagged
and the transmission will adopt the default function.
ROTARY SWITCH
(GB002)
PIN 1 -SWITCH COMMON
PIN
2 -CODE X OUTPUT
PIN
3 -CODE Y OUTPUT
PIN
4 -CODE Z OUTPUT
Possible causes
Open circuit on X, Y or Z line from rotary switch.
9 Faulty operation of rotary switch.
Effects:
. MIL illuminated.
. Transmission warning lamp illuminated.
. Maximum fluid pressure applied.
. Limp home mode applied.
Remedy:
. Repair or renew harness I connectors.
. Check selector cable and adjust or renew if necessary.
. Check rotary switch and adjust or renew if necessary.
X300 EDM Issue 1 August 1994 6

Automatic Transmission (AJ16)
OUTPUT SPEED SENSOR - P 0721 / P 0722
The output speed sensor is located on the rear of thevalve block assembly inside the transmission. Connection is made
via pins A and F of the %way transmission connector located on the left hand side of the transmission assembly. The
wiring runs through the rotary switch harness and the vehicle gearbox harness to the TCM on pins 2 and 38 of the 55 way multi-plug. These wires are shielded by a screen which is terminated on pin 20 of the TCM multi-plug. The sensor
detects the motion of the output shaft via a 36 toothed wheel.
TCM ROTARY SWITCH TRANSMISSION
(CC007) (GB002) (GB003)
PIN 2 -SIGNAL PIN 11 -SIGNAL PIN F -SIGNAL
PIN 38
- GROUND PIN 12 -GROUND PIN
A - GROUND
OUTPUT SPEED SENSOR CIRCUIT RANGE/ PERFORMANCE - P 0721
This test is only performed when a downshift takes place and therefore the vehicle must be in a forward gear ie D, 3, 2, 1. A fault will be flagged if the engine speed is above a threshold which is dependant on the shift and the state of the lock up clutch.
This fault code would suggest that there is an intermittent fault in the circuit.
OUTPUT SPEED SENSOR CIRCUIT NO SIGNAL - P 0722
The background diagnostic software continuously monitors the output speed and flags this fault if the output speed
is zero when the engine speed is greater than 2000 rpm and a forward gear, D, 3,2,1, is selected.
This fault code would suggest
a permanent fault, either open circuit, short to ground or short circuit to battery positive
voltage (+12V nominal).
Possible causes:
Faulty sensor.
Faulty harness wiring I connectors.
Effects:
MIL illuminated.
Transmission warning lamp illuminated.
Maximum pressure applied.
Limp home mode applied.
Remedy:
Renew sensor.
Repair or renew harness I connectors. ~~~~ ~~
Issue 1 August 1994 10 X300 EDM

w Automatic Transmission (AJ16)
ENGINE SPEED INPUT - P 0726 / P 0727
The engine speed input signal is a square wave output from the ECM. The signal is 12 volt active high with a duty cycle
of 50" / 120" of crankshaft revolution ie 3 pulses per revolution. The frequency of the signal is proportional to engine
speed.
TCM
PI HARNESS ECM
CC007/003 P1063/002 Pl104/022
ENGINE SPEED INPUT CIRCUIT - RANGE / PERFORMANCE P 0726
Engine speed is continuously monitored by the background diagnostics. This fault is flagged if the engine speed ex-
ceeds the maximum speed threshold (approx 6800 rpm). This fault code would suggest an intermittent fault in the cir- cuit.
ENGINE SPEED INPUT CIRCUIT NO SIGNAL - P 0727
If the engine speed drops below 95 rpm and the selected gear is not P or N, then the TCM will initiate the default mode.
This fault code will only be stored if the output speed is greater than 300 rpm. This is to prevent spurious flagging of
codes if the engine stalls.
Possible causes:
. Faulty harness wiring 1 connectors.
. Faulty signal from ECM.
Effects:
. MIL illuminated.
. Transmission warning lamp illuminated.
. Maximum fluid pressure applied.
. Limp home mode applied.
Remedy:
. Repair or renew harness /connectors.
. Examine ECM fault diagnosis (refer to EC Section 1).
Issue 1 August 1994 12 X300 EDM

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

Automatic Transmission (AJ16)
TP ELECTRICAL SIGNAL SYSTEM - P 1791
If the throttle angle signal line is held permanently high or low for more than looms, then this fault will be recognised
and stored. The TCM will adopt the substitute throttle value and turn on the warning lamp. The fault code will only be
stored if the engine speed is greater than 400rpm.
TCM PI HARNESS ECM
CC007/047 P1063/00 1 PI 1041032
Possible causes:
Faulty harness wiring I connection.
. Faulty ECM signal.
Effects:
Transmission warning lamp illuminated.
. MIL illuminated.
Normal mode only available.
Substitute throttle angle adopted.
No kickdown facility.
Remedy:
Repair or renew harness 1 connector.
Examine ECM fault diagnosis (refer to EDM, Section 5.1).
TP SIGNAL SYSTEM RANGE/ PERFORMANCE - P 1790
The throttle signal is a pulse width modulated (pwm) input which runs at a constant frequency of 183 Hz the information is contained in the duty cycle of the signal. If this information is out of range, that is, the duty cycle is less than 5% or
greater than 94%, then the TCM will use a substitute throttle value of 47% and will light the warning lamp and this fault code will be stored. During cranking, this signal is used to convey the engine coolant temperature. The coolant tem- perature signal persistsfor 500 msec after reaching the engine run threshold of 400 rpm. If theTCM does not recognise a valid throttle angle signal afterthis time then a substitute throttle value (47%) will be used and the warning lamp will
be
lit and this fault code will be stored. A fault code will only be stored if the engine speed is greater than 400 rpm. If an out of range coolant temperature is received then a substitute coolant temperature value (77" C) is used but no fault is stored.
X300 EDM 21 Issue 1 August 1994

lw Automatic Transmission (AJ16)
SYSTEM VOLTAGE MALFUNCTION - P 1794
The TCM monitors the supply voltage and will log this fault if the voltage is less than 10.5V when the engine speed is
greaterthan 1600rpm. This fault code is unlikelyto becaused by afault within theTCM and assuch thevehicle harness
and fuses etc. should be completely tested before the TCM is condemned.
Possible causes:
. Blown fuses.
. Faulty harness wiring /connections.
Effects:
Transmission default settings adopted.
. MIL illuminated.
Transmission warning lamp illuminated.
. Maximum fluid pressure available.
. Limp home mode applied.
Remedy:
Examine fuse F14 in LH heelboard fuse-box. Renew (if necessary) after determining cause of rupture.
. Repair or renew harness / connector.
KICK-DOWN SWITCH SYSTEM - P 1796
The diagnostic check on the mode switch input is a plausibility check which is performed continuously while in oper- ation. A fault is determined when kickdown is seen when the throttle angle is less than 50%. However a fault will only
be logged if the output speed is greater than 256 rpm. No fault is logged if there is already a throttle signal fault. The
kickdown switch is located on the floor under the accelerator pedal and is operated when the throttle is fully open (ap- prox 90%). It is a normally open switch with one contact permanently to ground and the other is a signal to the TCM.
The signal wire is routed through the bulkhead harness and the gearbox harness to the TCM.
LHD
(FCO19) PIN 2 GROUND PIN 1 KD
SIGNAL
RHD
(CA074) PIN 2 GROUND PIN 1 KD
SIGNAL
Possible causes
. Faulty harness wiring /connections.
. Faulty switch (or switch adjustment).
Effects:
No kickdown facility.
Remedy:
. Repair or renew harness /connector.
. Re-adjust or renew switch.
0
0
0
Q
Issue 1 August 1994 24 X300 EDM