1997 ASTON MARTIN DB7 Instrument

^?
Air Conditioning Repair Procedures
upper/Lower Servo Feedback Potentiometer Renew

8.2.03.1
Upper Servo Feedback
Potentiometer Renewal

8.2.04.1
Lower Servo Feedback
Potentiometer Renew

1.
Disconnect the battery earth
lead.

2.
(On left hand cars) Remove the instrument paci<
and surround
trim.

2.
(On right hand cars) Remove the glove box
assembly.
3.
Remove the
securing screws
and
the potentiometer
assembly. Disconnect the electrical connector.

4.
Fitting a new potentiometer is the reverse of the
removal procedure.

1.
Disconnect the battery earth
lead.

2.
Un-clip and remove the left hand underscuttle

casing.

Figure 1.
3. Disconnect the electrical block connector
(Fig.
1).

4.
Remove the securing screw and the potentiometer
assembly.
5. Fitting a new potentiometer is the reversal of the
removal procedure.
May 1996 8-57

'nzm^=2?
Air Conditioning Repair Procedures
Blower Motor Renewal
8.2.07.1 Ambient Temperature Sensor
Renew

?\gure
1.
The ambient temperature sensor is located in the
left hand side of the air plenum chamber under the
lower windshield panel (Fig. 1-1).
Procedure

1.
Disconnect the battery earth
lead.

2.
(On left hand cars) Remove the steering wheel
(mark the position on the column shaft for re­
assembly), instrument pack and surround
trim.

2.
(On right hand cars) Removethegloveboxlidand
liner.
3. Disconnect the hose from the distribution box to
the side vent outlet. Reposition the hose for access.

4.
Disconnect the sensor block connector.
The sensor has locating clips and is a push fit into
the plenum chamber.
5. Lever the sensor free.
8.2.08.1 Blower Motor Driver Side
Renewal
8.2.09.1 Blower Motor Passenger Side
Renewal

1.
Move seat
fu 1
ly rearward.

2.
Disconnect vehicle battery ground
lead.

3. Remove the under scuttle/knee pad bolster.

4.
Remove the lower brace bar/facia assembly
underscuttle knee pad.
Driver Side Only
5. Removetheinstrumentpack, bonnetreieasehandle
mounting bracket and steering column..
6. Disconnect the air hose from the facia side air
outlet.
Passenger Side Only
7. Remove the glove box lid and liner.
Both
8. Remove the nuts securing the component panel

(Fig.
1-1).
Figure 1.
9. Ease the component panel clear for access to the
blower assembly mounting bolts.

10.
Disconnect the pliable trunking from the stub pipes
on either side of the air conditioning unit
(Fig.
1
-3).

11.
Disconnect the blower motor electrical harness at
the block connector.
May 1996 8-59

Air Conditioning Repair Procedures
Water Temperature Switch/Heater Matrix Renew •=2?
8.2.12.1 Water Temperature Switch
Renewal

1.
Disconnect the battery earth
lead.

2.
Un-clip and remove the left hand underscuttle

casing.

Figure.
3. Note and disconnect the feed wires from the switch

(Fig.
1-1).

4.
Displace and remove the switch from the water

pipe.

5. Fitting a new switch is the reversal of the removal
procedure.
8.2.13.1 Heater Matrix Renewal

1.
Disconnect the battery earth
lead.

2.
Remove the left hand underscuttle panel.
3. (On right hand cars) Remove the glove box
assembly.
3. (On left hand cars) Remove the instrument pack
and surround
trim,
steering column and mounting
bracket.

4.
Drain the coolant into a suitable container.
5. Remove the matrix cover panel securing screws.
6. Removethe rear
panel,
displacethefront panel and
foam seal for access.
7. Place rag in position.
8. Remove screws securing the feed pipe and
disconnect the pipe from the matrix.
9. Remove and discard the gasket.

10.
Remove the screws securing the feed pipe and
disconnect the pipe from the matrix.

11.
Remove and discard the gasket.

12.
Disconnectthewatertemperatureswitchfeedwires.

13.
Remove the foam pad from the pipes.

14.
Remove the front panel from the unit.

15.
Undo the heater hose matrix pipe hose clips and
disconnect the hoses from the pipes.

16.
Reposition the pipes from the matrix.

1
7. Remove the matrix from the air conditioning unit.

18.
Fitting a new matrix is the reversal of the removal
procedure.

19.
Ensure that new gaskets are fitted.
8-62 May 1996

^>
Air Conditioning Repair Procedures
Electronic Control Module/Vacuum Solenoid Renewal
8.2.14.1 Electronic Control Module
Renew
8.3.01.1 Vacuum System Solenoid
Renewal

1.
Disconnect the battery earth
lead.

2.
Remove the right hand underscuttle casing.
3. (On left hand cars) Removethe glove box assembly.
3. (On right hand cars) Remove the instrument pack
and surround
trim.

4.
Disconnect the earth wire and three block
connectors from the control module (Fig.
1
-2).
5. Remove the securing screws and module from the
air conditioning unit (Fig. 1-1).
Fitting a new module
is
the reversal of the removal
procedure.
The flaps in the cabin air distribution vents and the
water valve in the pipe line from the engine coolant
system to the heater matrix are all operated by
vacuumactuators.The vacuumfor these issupplied
by four solenoids mounted in a manifold pack
located behind the front left hand footwell outlet.
Failureof a solenoid will require replacement of the
manifold pack.
Procedure

1.
Disconnect the battery earth
lead.

2.
Remove the following:
• glove box and lid
• facia trim (walnut strip)
• radio and ashtray
• centre console switch assembly
• left hand underscuttle casing/knee bolster
Detai
Is
ofthe above operations can be found in the
trim and the electrical sections.

2.
Remove thefixings joining the centre console to the

facia.
This allows the front of the console to be
repositioned for access.
3. Disconnect the ducting from the left hand footwell
outlet.

4.
Remove the two plastic fixings that secure the
slotted footwel
I
outlet and
si
ide the outlet out ofthe
unit.
7. Cut the tie strap holding the vacuum lines and
electrical harness to the underside of the air
conditioning unit.
8. Remove the screws that secure the manifold pack
to the underside of the air conditioning unit and
slide out the plate complete with the manifold
pack.

10.
To fit a new manifold pack reverse the steps for the

removal.

May 1996 8-63

' -^ ^ The Aston Martin Lagonda Diagnostic System
Installation Instructions
Service Centres
UK and EIRE
GenRad Limited, Horsefield Way, Bredbury Industrial Park, Bredbury, Stockport, Cheshire SK6 2SU, England
Telephone: 061-406-8209 Fax: 061-406-8480
Germany
GenRad GmbH, Neumarkter Strasse 83, 81673 Munchen, Germany
Telephone: 01049-89-431990 Fax: 01049-89-43199101
Switzerland and Austria
GenRad AG, Drahzug Strasse 18, Postfach 8032, Zurich, Switzerland
Telephone: 010411-422-2420 Fax: 010411-422-2065
Italy
GenRad SPA, Via Fantoli 21/13, 20138 Milano, Italy
Telephone: 01039-2-502951 Fax: 01039-2-5063331
France, Spain and Portugal
GenRad Europe Paris, Succursale de GenRad Europe Limited, 6 Rue Vincent Van Gogh, 93364, Neuilly Plaisance
Cedex, France.
Telephone: 01033-1-49442200 Fax: 01033-1-49442298

Sweden,
Norway, Denmark and Finland
Lagercrantz Kontest AB, Kung Hans vag 3, Box 986, 191 29 Sollentuna, Sweden
Telephone: 01046-8-626-06-20 Fax: 01046-8-754-88-67
Netherlands, Belgium and Luxembourg
Multidata BV, Postbus 137, Bedrijvencentrum "De Baanderije", ParallelwegZuid 33/1,5280 AC Boztel, Netherlands
Telephone: 01031-4116-83775 Fax: 01031-4116-85359
USA and Canada
GenRad Inc, 300 Baker Avenue, Concord, Massachusetts,
1
742, USA.
Telephone: 0101-508-369-4400 Fax: 0101-508-287-2011
Singapore, Taiwan, Hong Kong and Thailand
GenRad Inc, 73 Science Park Drive, Cintech Building #03-04, Singapore, Singapore 0511.
Telephone: 01065-2784400 Fax: 01065-7766422
Australia and New Zealand
Nilsen Instruments, 25-27 Paul Street North, North Ryde, New South Wales 2113, Australia.
Telephone: 01061-2-7362888 Fax: 01061-2-7363005
Japan
Tokyo Electron Limited, 2-30-7 Sumiyoshi-Cho, Fuchu City, Tokyo, Japan 183
Telephone: 01081-423-33-8377 Fax: 01081-423-33-8489
May 1996 9-21

^^
The Aston Martin Lagonda Diagnostic System
Installation Instructions
Statement of Calibration
Product Range Aston Martin Diagnostic System
Product Type Portable Diagnostic Unit
Product Number 3130-001 7
We certify that the above product has been tested and found to conform to the product specification, priorto dispatch
from GenRad. The measurements performed by this equipment are traceable to international measurement
standards. Calibration records, including the date of calibration and the serial numbers of the measurement
instruments are maintained by GenRad and are traceable through the PDU System serial number.

NOTE:
The PDU will not require any periodic adjustment in order to maintain specified measurement accuracy.
Calibration Measurements
Ambient temperature during calibration 20±1 °C.
The test resistances in the table below are applied between the red and black probes. The PDU is set to measure
resistance between these probes using the DMM function. The PDU reading must be between the limits shown.
Test Resistance
10Q
10MQ
PDU Reading Limits
9.84f2-10.16Q
8.22MQ -11.78MQ
The test voltages in the table below are applied between the red and black probes. The PDU is set to measure voltage
between these probes using the DMM function. The PDU reading must be between the limits shown.
Voltage
50mV
lOOmV
160mV
350mV
720mV
1.45V
2.90V
7.25V
14.5V
29V
49V
98V
175V
PDU Reading Limits
48mV - 52mV
98mV - 102mV
157mV -163mV
345mV-355mV
712mV-728mV
1.43V - 1.47V
2.86V-2.94V
7.1 7V - 7.33V
14.35V- 14.65V
28.7V-29.3V
48.5V-49.5V
97.0V-99.0V
173.7V-176.3V
May 1996 9-25

^^?
The Aston Martin Lagonda Diagnostic System
Users Guide
Transmission Diagnostics
Selecting 'Transmission from the vehicle area menu will
present the technician with the following transmission
diagnostic tools menu:
Transmission Diagnostic
• Datalogger
• Diagnostic Trouble Codes
o
The Datalogger function is fully described in the worked
example at the rear of this PDU Users Guide.
Transmission Datalogger
The PDU datalogger function may be used to monitor the
following transmission controller signals
DIGS Number of DTCs Logged
The Diagnostics status manager (DSM) receives and
processes fault information and decides when a DTC
should be logged and the MIL turned on (if enabled). The
actual total stored is indicated by the parameter DTCS.
FBRAKE Brake Switch
The footbrake switch signal is input to the
TCM.
The input
is normally at ground potential and goes open circuit
when the brakes are applied. If the torque converter
clutch is applied it will disengage when this signal is

detected.

FMA Actual Force Motor Current
The force motor regulates the transmission fluid pressure.
It is a variable force solenoid whose coil current is
determined by the TCM. Range 0 -1.245 amps. A driver
circuit limits excessive current flow and performs a
ratiometric comparison of Desired (commanded) Force
Motor Current and Actual Force Motor current. The
parameter monitors the Actual Force Motor current 1 Bit
= l/204.8amps.
HOT Hot Mode
The signal from the transmission temperature sensor is
used to control TCC and line pressure. It is also used in
many diagnostic signals and is a critical component for
OBD II. Above 120°C the TCC is on in 2nd, 3rd and 4th

gears.
This reduces transmission temperature by decreasing
the heat generated by the torque converter. It also
provides maximum cooling by routing transmission fluid
directly to the transmission cooler in the radiator. When
the Hot Mode is ON the bit is set to 1.
IGN+ Ignition Feed Positive
The TCM receives ignition voltage through TCM pin 53.
MD Desired Force Motor Current
The force motor regulates the transmission fluid pressure.
It is a variable force solenoid whose coil current is
determined by the TCM. Range 0 -1.245 amps. A driver
circuit limits excessive current flow and performs a
ratiometric comparison of Desired (commanded) Force
Motor Current. The parameter mon itors the Desired Force
Motor current 1 Bit = 1/204.8amps.
RATIO Actual Gear Ratio
The diagnostic detects malfunction in the transmission
output components by monitoring the actual gear ratio.
The actual gear ratio is calculated using input (Ni) and
output speed (No): Ratio = Ni/No. This is compared with
the standard gear ratio for each gear. Malfunction can be
defined as: actual gear ratio is not equal to any of the
standard gear ratios.
RPM Engine Speed
The engine speed signal is input from the instrument pack.
The
signal
origi
nates
at the crankshaft
sensor.
The crankshaft
sensor signal is modified by the PCM and the instrument
pack before being input to the TCM.
SSA Shift Solenoid A
Shift solenoid A is attached to the valve body and its outlet
is open to exhaust when it is switched off. A OFF - outlet
open - 2nd and 3rd gears selected. The solenoid is
energised by the TCM providing an internal ground to
close the outlet. A ON - outlet closed -1 st and 4th gears

selected.

SSB Shift Solenoid B
Shift solenoid B is attached to the valve body and its outlet
is open to exhaust when it is switched off. B OFF - outlet
open - 1st and 2nd gears selected. The solenoid is
energised by the TCM providing an internal ground to
close the outlet. B ON - outlet closed - 3rd and 4th gears

selected.

September 1996 9-41

^^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