1997 ASTON MARTIN DB7 sensor

The Aston Martin Lagonda Diagnostic System
Users Guide ^7
TCCS Torque Convertor Clutch Solenoid
The torque converter clutch solenoid is mounted on the
valve body. The signal is Pulse Width Modulated at 32Hz
to provide closed loop control of the pressure across the
converter clutch plates. 1 bit = 0.39% Range 0 to 100%
TP Throttle Position
This is provided by the EECV Engine Management System
as a Pulse Width Modulated signal derived from the
throttle position signal read by that module from the
throttle position sensor.
TCS Torque Convertor Slip
Torque converter slip is defined
as
the difference between
the Input/turbine (ni) speed and the Engine speed (Ne):
Slip = Ne-Ni. The PWM duty cycle may increase from 0
to 100% when TCC is fully applied. In practice a 100%
duty cycle will be achieved only if
a
large slip is detected.
Normal ly only a 50 to 95% duty cycle will be required for
full application of the TCC. Slip is expressed in rpm. 1 Bit
- 1/8 rpm. Range -4096 to +4096 rpm.
TCSW Transmission Control Switch
A three position switch allows the driver to select Sport,
Normal or 1st Gear Inhibit mode. When 'Sport' is selected
gearshifts take place at higher engine revs. When '1st
Gear Inhibit' is selected, the transmission only operates in
the higher forward ratios to prevent wheel slip in icy
conditions.
TISSA Turbine Input Shaft Speed
Turbine speed is the speed of the input shaft of the
transmission measured by the input speed sensor mounted
on the transmission. An alternating waveform is induced
in the sensor by 31 serrations on the forward clutch
housing as it rotates. The waveform frequency and
amplitude is low at low speeds and high at high speeds.
The TCM changes this signal into a digital signal. 1 bit =
1/8 RPM. Range: 0 - 8192 RPM.
TOS+ Transmission Output Speed
The output speed sensor is mounted on the transmission
case and measures the speed of the output shaft. As the
shaft rotates an alternating waveform is induced in the
sensor which varies in frequency and voltage. The wave
form is converted into
a
digital signal by the TCM and used
to control TCC, line pressure, shift timing and torque
management. 1 bit = 1/8 RPM. Range 0-8192 RPM
TRX Transmission Control Switch X
TRY Transmission Control Switch Y
TRZ Transmission Control Switch Z
The transmission range is detected by the pressure switch
manifold (PSM) and input to the
TCM.
The signal consists
of three discrete lines X, Y, Z which transmit a 3 bit binary
code as shown in the table below.
0 = open circuit
1 = short circuit to ground
X Y Z
p
R
N
D
3
2
Error
0
1
0
1
0
0
1
0
0
0
0
1
1
1
0
1
0
0
1
0
1
VS Vehicle Speed
Veh icie speed
is
derived from
a pu Ised
wave form generated
by the speed sensor in the hypoid unit. There are 40 pulses
per shaft rotation and the TCM converts this to vehicle
speed and applies correction for axle ratio and road wheel
diameter. 1 bit -
1
kph. Range 0 - 255kph
Transmission Diagnostic Trouble Codes
The diagnostic trouble codes supported by the CM 4L80-

E
Transmission Control Module are covered indetail inthe
DB7 OBD II Diagnostics Manual.
TOT Transmission Oil Temperature
The transmission temperature sensor signal is used to
control TCC and line
pressure.
It
has a
negative temperature
coefficient so when the temperature is cold its resistance
is high and the TCM sees
a
high voltage. Asthe temperature
warms the volts drop across the sensor decreases and the
signal voltage becomes lower. The TCM converts this
analogue input into a digital signal.
1 bit =
1
°C Range -55°C to +200°C.
9-42 September 1996

^?
The Aston Martin Lagonda Diagnostic System
Users Guide
Climate Control Diagnostics
The air conditioning control module is located at the right
end of the air conditioning unit. Since this controller uses
a unique communications protocol, the PDU must be
connected directly to the unit via the Vehicle Inerface
Adaptor as shown in the following cable setup screen.
Cable Setup
Adigitalmicroprocessorwithin the control module receives
data signals from the operator controlled switches.
Comparison of these signals with those returned from
system temperature sensors and feedback devices results
in the appropriate output voltage changes needed to vary:
Blower motor speed, flap position and the solenoids
which respond to operator selected temperature demand.
The air from two blower motors is passed through the
evaporator matrix which, depending on the positions of
the humidity buttons, removes heat from the incoming air.
Dependingon the position of the two blend flaps, the cold
air either passes directly to the vehicle outlet vents, or is
passed through the heater matrix to be reheated and then
to the vehicle outlet vents.
The amount of air passing through the heater matrix is
infinitely variable depending on ambienttemperature and
the temperature selected within the vehicle.
Selecting 'Climate Control' from the vehicle area menu,
will presentthetechnician with the dataloggertool selection

screen.

Details of the signals which may be monitored in the
system may be found in the DB7 Workshop Manual -
Section 8 - Air Conditioning'
Anti-Lock Braking Diagnostics
The Teves Mk IV Braking System consists of two sub­
systems, power braking and anti-lock braking.
The PDU software(DataLogger) only allows the monitoring
of the anti-lock braking system.
The ABS System consists of:
Four wheel speed sensors.
One control module.
Seven solenoid valves.
One pressure switch.
One fluid level switch.
The ABS System
is
controlled and continuously monitored
by the ABS control module, which automatically
switchesoffthesystemifafailure is identified, illuminating
a warning lamp and leaving
full,
boosted braking to all
wheels. A wheel speed sensor is installed at each wheel.
Their wheel speed related signals are processed by the
control module, which triggers the solenoid valves to
modulate hydraulic pressure, preventing the wheels from

locking.
The control module also monitors the fluid
level and will inhibit ABS operation should lowfluid level
be detected.
The Datalogger function will permit monitoring of the
complete system apart from the solenoid valves. The
control module transmits short duration test pulses of 25
to 100 microseconds to the solenoid valves. These
pulses are too fast for the PDU to monitor and as a result
would cause confusing waveforms.
Selecting 'Anti-Lock Braking' from the vehicle area menu,
will present the technician with the following menu of
diagnostic tools screen:
Anti-Lock Brakes Diagnostic
Datalogger
Diagnostic Trouble Codes
o
ABS Diagnostic Trouble Codes
The DTCs which are supported in the Teves Mk IV ABS
system are listed in the workshop manual - Section 5
Brakes Wheels and Tyres.
September 1996 9-43

The Aston Martin Lagonda Diagnostic System
Users Guide
Em^'^?

ABS Datalogger
The following signals in the Teves Mk IV ABS system may
be monitored using the datalogger function.
DTCs Number of DTCs Logged
The Diagnostic status manager (DSM) receives and
processes fault information and decides when a DTC
should be logged and the MIL turned on. The actual total
stored is indicated by the parameter.
FBRAKE Brake Switch
The signal from the brake switch is used by the CM to
ensure that traction control is inhibited when the brakes
are applied. The input circuitry within the CM is a
1
OK
pull-up to ignition voltage. When the switch is closed the
parameter is set to 1.
FLWS Front Left Wheel Speed Sensor
An indication sensor outputs a sinusoidal wave form 48
pulses per revolution. The output is processed by the CM
to control braking and traction. The sensor is continually
monitored for open and short failure and operating range.
If its output exceeds 330km/h it is deemed to be faulty and
the CM is disabled. The parameter tracks the sensor
weaveform through 255 steps.
FRWS Front Right Wheel Speed Sensor
An indication sensor outputs a sinusoidal wave form 48
pulses per revolution. The output is processed by the CM
to control braking and traction. The sensor is continually
monitored for open and short failure and operating range.
If its output exceeds 330km/h it
is
deemed to be faulty and
the CM is disabled. The parameter tracks the sensor
weaveform through 255 steps.
RLWS Rear Left Wheel Speed Sensor
An indication sensor outputs a sinusoidal wave form 48
pulses per revolution. The output is processed by the CM
to control braking and traction. The sensor is continually
monitored for open and short failure and operating range.
If its output exceeds 330km/h it
is
deemed to be faulty and
the CM is disabled. The parameter tracks the sensor
weaveform through 255 steps.
RRWS Rear Right Wheel Speed Sensor
An indication sensor outputs a sinusoidal wave form 48
pulses per revolution. The output is processed by the CM
to control braking and traction. The sensor is continually
monitored for open and short failure and operating range.
If its output exceeds 330km/h it is deemed to be faulty and
the CM is disabled. The parameter tracks the sensor
waveform through 255 steps.
Passive Anti Theft (PATS) Diagnostics
Security System Diagnostics
Becauseof the requirementto maintain vehicle security,
the PATS and Security System operating instructions
and diagnostics are covered in the Vehicle Security
supplement to section 6 of the workshop manual. This
supplement has restricted circulation and is only
available to Aston Martin Dealers.
9-44 September 1996

^^2?
The Aston Martin Lagonda Diagnostic System
Users Guide
Airbag System Diagnostics
WARNING: Whilst it
is
completely safe to
access

and read the airbag diagnostic module memory at
the diagnostic socket, significant personal risks
exist in the performance of any other
tasks
on the
airbag system or components. Therefore all
workshop manual warnings must be read and all
safety procedures must be followed before, during
and on completion of any other practical work on
the airbag system.
System Description
The airbag system installation comprises:
Airbag Diagnostic Module
Driver and passenger airbag modules
Two front impact (crash) sensors
One 'safing' sensor
Dedicated wiring harness
SRS indicator/warning lamp
The system is designed to provide protection for both
driver and front seat passenger by automatically
deploying airbags in the event of a collision during
forward travel.
Intheeventof
a
collision, the crash and safing sensors
will operate, completing the firing circuit and causing
the airbags to inflate within 32 milliseconds. At least
one crash sensor and the safing sensor must operate to
fire the airbags.
Any faults in system components, installation or wiring
will be indicated by a flashing code on the SRS/
AIRBAG warning lamp. Fault code information may
also be monitored using the PDU or scan
tool.

A full description of the airbag system components is
included in the workshop manual.
Airbag Diagnostics
The Airbag Control Module indicates a fault by
transmitting a pulsed signal down the Airbag System
Failure line to flash the SRS/AIRBAC warning lamp.
The fault code is repeated continuously. If there are
two or more faults, the fault code with the highest
priority is transmitted first. The second fault code is
only transmitted when the first fault has been rectified.
TheSRS/AIRBAC warning lamp is also used to indicate
any problem in the seat belt pretensioner system (if
fitted). Flashing of the lamp indicates an airbag fault,
constant illumination of the lamp indicates a seat belt
pretensioner fault.
At the top left of the PDU screen there is a bullet mark
which indicates the current state of the Airbag System
Failure line. As a code is transmitted the bullet mark
can be seen to flash.The PDU reads the fault code, and
writes the code number and fault description to the

screen.
The PDU continues to monitor the transmitted

code.
If the transmitted code changes, the new code
number and description will appear below the first.
PMC Airbag
32 Drivers airbag circuit
shorted or open
o
when remedial action has been taken to correct a
fault, press the Clear Button to clear down the PDU
display. Then use the PDU to ensure that no faults are

reported.

A series of audible beeps, continuously transmitted by
the Airbag Diagnostic Module, indicates that there is
an Airbag System fault to report and that the Airbag
System Failure line
is
open circuit. The PDU is notable
to monitor the fault line in this situation as there is no
pull-up resistor, normally provided by a warning lamp
in the instrument pack.
Rapid continuous flashing of the Instrument Pack
Airbag Failure Lamp indicates that both front impact
sensors are disconnected. No fault code is reported on
the PDU, however on close inspection the bullet mark
can be seen to flicker.
September 1996 9-45

The Aston Martin Lagonda Diagnostic System //~~^ ^?~?^ " ^ ^
Users Guide
Airbag Diagnostic Trouble Code Monitor
The following diagnostic trouble codes are supported by the Airbag Control Module:
12 Low battery voltage
13 Air bag circuit shorted to ground
14 Front inpact sensor circuit shorted to ground
21 Safing impact sensor incorrectly mounter to vehicle
22 Safing impact sensor output shorted to battery voltage
23 Safing impact sensor input feed / return open circuit
24 Safing impact sensor output feed / return open circuit
32 Driver side airbag circuit high resistance or open
33 Passenger side airbag circuit high resistance or open
34 Driver side airbag circuit low resistance or short circuit
41 Front right impact sensor feed / return open circuit
42 Front left impact sensor feed / return open circuit
44 Front right impact sensor incorrectly mounted to vehicle
45 Front left impact sensor incorrectly mounted to vehicle
51 Airbag CM internal thermal fuse - intermittent short to ground
52 Back up power supply - voltage boost fault
53 Front impact sensor circuits resistance to ground or internal Airbag CM failure
9-46 September 1996

The Aston Martin Lagonda Diagnostic System
Users Guide ^?
Seatbelt Pretensioner Diagnostic Trouble Codes
050A Pretensioner squib leak to battery positive
050B Pretensioner squib leak to ground
050C Pretensioner squib high resistance
050D Pretensioner squib low resistance
0D13 Capacitor voltage error
0D14 Capacitor capacitance
0D09 Energy reserve switch
0D1E Energy shutdown switch
050E Seatbelt pretensioner switch error
0109 Accelerometer function
01OA Acceleration out of range

01
OB Accelerometer offset
0209 Safing sensor error
030A Temperature sensor error
060C Warning lamp short circuit
060D Warning lamp open circuit
060E Warning lamp driver error
OAOC Analogue voltage error
0A09 Communications error
090A EEPROM not programmed
0909 EEPROM checksum
OAOA External watchdog error
OAOB External watchdog time out
020A Safing sensor not closed
090C RAM check error
9-48 September 1996

^^?
The Aston Martin Lagonda Diagnostic System
Users Guide
The following trigger options are available:
Triggers when the signal passes above
a
specified

value,
i.e. stop lamp.
Triggers when the signal passes below
a
specified

value,
i.e. Anti-Lock brakes warning lamp.
Triggers when the signa
I
passes outside
a
specified

band,
i.e. oxygen sensor feedback.
Triggers when the signal passes into a specified

band.

Once the type of trigger has been selected the trigger
vaiue(s) (i.e. the signal level at which the trigger point wil
I

occur) should be set.
These values are set by highlighting the existing value.

i
jr:
ECT ^ 1
Trigger KBIT" ^
^^^^1

S.I.

°c
Oj
Engine coolant temperature

m
^
Highlighted Trigger Value
Press the calculator-style
icon.

A new screen should now be displayed.
Trigger Value Entry
Enter the required trigger value using the calculator-style
screen buttons.
The S.I. button enables unit selection, where applicable,
refer to S.I. Units.
Confirm the trigger value by pressing the 'tick'
icon.

The trigger screen will now be re-displayed.
Press the 'tick' icon to go back to the Parameter
Customisation screen.
Press the 'tick' icon again to return to the datalogger main

menu.

September 1996 9-59

^?
The Aston Martin Lagonda Diagnostic System
Users Guide
Datalogger Example
A customer reported intermittent illumination of the
anti-

Lock Brakes (ABS) warning lamp.
TheABScontrolmodulewas interrogated, producing fault
code 33 (95 MY), right-rear wheel speed sensor.
The PDU was used to check the wheel speed sensor
output using the ABS warning lamp as a trigger.
The PDU was setup to the vehicle's configurations and
Datalogger was accessed.
Datalogger automatically defaulted to the waveform

screen.

30V
MPROBE
OV
240KPH •
FLW<133
OKPH .
240KPH •
FRW<133
OKPH .
OS 95s 190s
^ ^ R • i=3
Datalogger Waveform Screen
The main menu icon was selected to access the main
menu screen.
The main menu screen is the main control screen for
access to Datalogger's subsystems.
^/^
The customisation icon was selected, and the
selection was confirmed using the 'tick'
icon.

The parameter customisation screen was then displayed.
Signals • c05 d^ CZf S.I.
ABSWL
BAT+P20
BAT+P3
FLS2
FLW<133
FLW>133
FRW<133
•
•
•
•
7
6

2||

3
V
V
V
1 2 3 W c
V
KPH
KPH
KPH
^=3
Parameter Customisation Screen
All pre-defined parameters were cancelled using the 'C

icon,
the screen was now similar to that below.
Signals ^ (n> •S'- rz^ S.I.
ABSWL
BAT+P20
BAT+P3
FLS2
FLW<133
FLW>133
FRW<133
V
V
V
A B C
1 2 3 ^ ^ i i C
V
KPH
KPH
KPH
Datalogger Main Menu
Fig. 35 Parameter Setup
The rectangle below the play icon next to 'ABSWl' (Anti-
lock Brakes System Warning Lamp) was selected to be

recorded.

The rectangle below the 'eye' icon in the 'ABSWl' row
was selected to be recorded.
The screen was scrolled down until 'RIW<133' was

displayed.

The rectangle below the play icon in row'RLW<133'was

selected.

The rectangle below the eye icon in row 'RLW<1 33' was

selected.

September 1996 9-63