
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  

IW Automatic Transmission (AJ16) 
TRANSMISSION  FLUID TEMPERATURE  SENSOR INPUTS P 0712 / P 0713 
The transmission  fluid temperature  sensor is a positive  temperature coefficient  thermistor bead, located in the internal 
wiring  harness  of the transmission assembly  and immersed in the transmission  fluid in the unit  sump.  The wiring  is 
taken  out through  the transmission connector and  runs through the rotary switch and  then into the gearbox  harness 
to  the  TCM.  The pin outs  on the  relevant parts  are as follows. 
TCM  ROTARY SWITCH  TRANSMISSION 
55 WAY CONNECTOR  12 WAY  MULTI-LOCK 9 PIN  DEUTSCH 
(CC007) (GB002) (GB003) 
PIN 46 - SIGNAL  PIN 8 -SIGNAL  PIN D -SIGNAL 
PIN 
44 -GROUND  PIN 9 - GROUND  PIN J -GROUND 
TRANSMISSION FLUID TEMPERATURE  SENSOR LOW INPUT- P 0712 
This input  is continuously  monitored during initialization  and operation by the  processor  and is checked against spe- cific  limits  to be  in range. If the  temperature indicated by  the sensor  is too low then this fault  code will be stored and 
the  processor  will use a substitute value  for the transmission  oil temperature. 
The  low limit  is approximately 
-50" C. This  fault  would  indicate  that the output signal line  (Pin 46) is probably short 
circuit  to ground. 
TRANSMISSION  FLUID TEMPERATURE  SENSOR HIGH INPUT- P 0713 
This input  is continuously  monitored during initialization  and operation by the processor and is checked against  spe- cific limits to  be in range. If the  temperature indicated by  the sensor  is too high  then this fault  code  will be stored and 
the  processor  will use a substitute value  for the transmission  oil temperature.  The high  limit is approximately 185" C. 
This fault  would  indicate  that the input  signal  line (Pin 46) is probably open  circuit or short circuit  to battery  positive 
voltage (+I2 nominal). 
Possible causes: 
. Faulty  sensor. 
. Faulty harness  wiring or connection  to sensor. 
Effects: 
. Substitute  oil temperature adopted by  TCM. 
Remedy: 
Renew internal  harness. 
. Repair or renew  harness I connectors. 
Issue 1 August 1994 8 X300 EDM  

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  

Automatic Transmission (AJ16) w 
8.1.5 
nector. 
TRANSMISSION  CONNECTOR 
(GB003) 
TRANSMISSION  ELECTRICAL PIN POINT TESTS 
THE FOLLOWING  TESTS describe  methods  of testing the  transmission  control solenoid  valves from the multi-pin con- 
0 A = Road Speed Sensor 
0 B = Pressure Regulator 
0 D = Oil Temperature  Signal 
0 F = Road Speed Sensor 
0 H = MVI Solenoid 
0 J = Oil Temperature  Ground 
0 K = MV2 Solenoid 
0 L = MWVK Solenoid 
0 M = Solenoid Supply 
The  solenoid  valves are located  on the  valve block  in the  transmission  assembly and can be identified by their  position. 
Connection  is made via  a connector  located on the  LHS  of the  transmission  assembly. 
Impedance  Checks 
M
-L) 
M
-K)  28-60ohm 
0 M-H) 
M-B 5-70hm 
M)(A 
K)(D 
L 1-( F O/C 
H)(J 
B)( 
L-K) 
L
- H ) 56- 120  ohm 
K
-H) 
L
-B) 
K
-B)  33-67ohm 
H
-B) 
All  Pins 
- Ground OK 
5 
m- 1738 
Fig. 1 Transmission  Multi-plug Connector 
X300 EDM 27 Issue 1 August  1994  

Automatic Transmission (V12) Powertrain 
8.2.1 POWERTRAIN 
41-80-E TRANSMISSION,  SYSTEM DESCRIPTION 
The electronic  transmission system  fitted to 6.0 liter and  4.0 liter super-charged  vehicles  comprises  the following  com- ponents: 
0 Hydra-matic 4L-80-E Automatic  Transmission 
0 Electronic Transmission  Control Module 
0 Performance  Mode Switch 
0 Kickdown  Switch 
0 Gear Selection  Module (illuminated) 
System  control is effected  by the transmission  control module 
(TCM), located  behind the passenger  side fascia, which continuously  monitors requests made bythe driver via the  gearselector,  throttle pedal etc. This  data  is used inconjunc- 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  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  selector  switch surround, can  be either  NOR- MAL, 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. 
8.2.2  COMPONENT  DESCRIPTIONS 
Transmission  Unit 
The powertrain  4L-80-E transmission  unit houses  the two  solenoid  valves which control  gear shifts. A pressure  control 
valve is  also located  on the  solenoid valve  block. These three valves  initiate  and control  shift patterns  within the  trans- mission unit by regulating  fluid flow. 
Performance  Mode Switch 
The two  position  performance  mode switch allows  selection of 'sport'  or 'normal'  mode as required  by the  driver.  The 
switch input to TCM  causes a  gear shift pattern change so that gear  shifts  take place at  higher engine  revs, enhancing 
performance,  when in 'sport'  mode.  For everyday  use, 'normal'  mode utilises  a shift pattern  for optimum  driver com- fort. 
Kickdown  Switch 
The 'kick-down'  facility  is activated  when full downward  travel of the  accelerator  pedal occurs. 
Activation  of the switch  provides a signal  to TCM  indicating  that greater  acceleration,  and hence  downward  gear shifts 
are  required.  Switch height is adjustable 
so that kick-down  can be achieved  at a pre-determined  throttle opening. 
Gear Selection Illumination Module 
This module  is located above  the gear  selector  mechanism  and its sole purpose is  to display  the selected gear (in red) 
on  receipt  of a signal  from the decoder  module. 
X300 EDM 1 Issue 1 August 1994  

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  

Automatic Transmission (V12) Powertrain 
Engine Speed 
The engine  speed is provided by  an open collector  signal supplied  from the engine  management  control module 
(ECM). 
Throttle Position 
This signal,  from the ECM,  performs the  following two functions: 
1. 
2. 
Engine  Torque  (and warm-up) 
This signal,  from the ECM,  performs the  following three functions: 
1.  During  cranking  to convey  the completion  of an  engine warm
-up  cycle  to TCM. 
2. To  convey engine  torque information,  under normal running  conditions, to TCM. 
3. To  convey engine  torque fault signals to TCM. 
Engine ‘warm
-up’  cycle commences  from ignition ON until 500ms after the engine  exceeds 400rpm. After this time 
delay  either  an engine torque,  or torque  fault signal  will be transmitted. 
Transmission Input Speed 
The  transmission  input speed sensor  is mounted  within the transmission housing  and produces a variable frequency 
signal,  directly  proportional  to forward  clutch housing rotational  speed which  is transmitted  to the  TCM.  Sensor resis- tance equals 1.25kQ f 0.25. 
Transmission  Output Speed 
The transmission  output speed sensor is mounted  within the transmission housing  and produces a variable frequency 
signal,  directly  proportional  to the  rear carrier  rotational speed which  is transmitted  to the  TCM.  Sensor resistance 
equals 
1.25w2 + 0.25. 
hake Application 
When a brake  application signal  is received, due  to brake  switch  operation,  the torque  convertor clutch  lock-up sole- noid  is de-energized,  releasing lock-up mode  if already  applied 
Transmission  Oil Temperature 
The  transmission oil temperature  sensor, located within the internal  harness,  monitors  oil temperature  and transmits a corresponding signal  to the  TCM. 
To convey  throttle position information  to the  TCM. 
To  indicate  fault conditions  between ECM and throttle  potentiometer. 
8.2.4.2 OUTPUTS 
Gear  Shift Solenoids 
The two  gear  shift solenoids, located  within the transmission  housing, determine  gear ratio  when  the selector  is in  any 
of the forward  gear positions. 
Force Motor 
The force  motor,  mounted within the transmission  housing acts as a transmission  torque fluid pressure regulator. 
Torque  Converter  Clutch (TCC) Solenoid 
The torque converter clutch  solenoid, mounted within the transmission  housing, provides a direct drive from the en- gine, via  the converter  clutch, to the driven  wheels, giving the  efficiency of a manual  gearbox.  The  solenoid also pro- vides a  ’ramp‘ apply and  release to engage / disengage  the clutch  gently. 
0 
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0 
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X300 EDM Issue 1 August 1994 6  

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Brakes ( 
12.1 COMPONENT LOCATlONS 
Fig. 1  AJ16 (normally aspirated) 
Fig. 
2 AJ16 (supercharged) 
Fig. 
3 VI2 
Key to Figs. 1,2 and 3: 
1. Throttle  position  sensor 4. ABS motor 
2. Traction control actuator 5. Valve block 3. Pump 6. Control module (ABS / TC CM) 
X300 EDM 1 Issue 1 August 1994