Starting ASTON MARTIN DB7 1997 Workshop Manual

^=2?
Electrics
Airbag System
Eye Protection
Chemical protective goggles are recommended
where there is a possibility of eye contact with the
propellant. Safety glasses with side shields are
recommended for all other operations.
Protective Clothing
Approved protective gloves, overalls and shoes/
boots should be worn.
Handling and Storage Precautions
Do not store airbag modules near live electrical
equipment or circuitry. Store in a dry environment
at ambient temperatures.
Good housekeeping and engineering practices
should be employed to prevent the generation and
accumulation of
dusts.
Store in compliance with all
local state and federal regulations.
Driver and Passenger Airbag Modules
Assembly/Removal/Service Instructions
WARNING: In the event of a vehicle impact where the
airbags and the seatbeltpretensioner (if fitted) are
deployed, the following actions MUST be
performed:
Check the condition of the seatbelts, steering

wheel,
steering column, all connections to airbags,
and the column switchgear connectors for integrity
and damage. If in any
doubt,
replace suspected
parts for new parts.
Replace both crash
sensors,
the
safing sensor
and
the seatbelt pretensioner module (if fitted).
On completion of all repair procedures, switch on
the ignition and check that the
Airbag/SRS
warning
light comes on when the ignition is switched on
and extinguishes after approximately six seconds
indicating satisfactory completion of the airbag
and pretensioner
system
self
tests.

WARNING: Before starting
work,
ensure
that the ignition
switch is in position 'O' and the ignition key is

removed.
Disconnect the battery negative lead
within 12 seconds of switching off the ignition to
prevent the alarm system triggering.
As the airbag control module is equipped with a
back-up power source and due to the risk of the
airbag being inadvertently deployed, wait one
minute or longer after disconnecting the battery
before starting work on the airbag module.
• Disconnectingthe battery negative cable cancels
the memory for the 'one-touch' window down
system and stops the vehicle clock. Reset the
window memory and the clock when work is

completed.

• Never use airbags from other vehicles, always
use new parts.
• After work is completed, reconnect the battery
and perform the airbag warning light check
• Never use electrical probes to check voltage or
electrical resistance of the airbag modules.
• Disconnect the airbag before carrying out any
work on, or in the vicinity of the module, or
when using electric welding equipment.
• Always ensure that the battery negative lead has
been disconnected for at least one minute before
commencing any removal procedure.
September 1996 6-71

'^^
Electrics
Seat Belt Pretensioner

6.6.26.1
Pretensioner Control Module -
Renew
Read the warnings given in system fault strategy
and service instructions on the previous page before
starting the following procedure.
Procedure

1.
Disconnect the battery ground (black) lead and
wait at least 10 minutes for the pretensioner power
supply to fully discharge before working on the
pretensioner system.
Note:
The
vehicle battery must
be
disconnected within
12
seconds
of switching off
the
ignition to avoid the alarm
siren sounding.
2. Motor the right front seat to its rearmost position.
3. Remove the floor carpet and the ECU cover.

4.
Disconnect the pretensioner control module
connector (orange connector with black safety

clip).

5. Remove 3 flange screws securing the module,
noting the position of the earth strap.
6. Fit the new pretensioner control module with the
connector facing to the rear and secure with 3
flange screwsensuringthatthe earth strap is secured
with the outboard rear screw.
7. Connect the orange connector to the control
module.
8. RefitandsecuretheECU cover and the floor carpet.
9. Reconnect the battery ground (black)
lead.

Note:
The
vehicle clock and the window control unit will
need
resetting
after completion of this procedure.

10.
Switch on the ignition and check that the airbag
warni ng I ight comes on when the ign ition
is
switched
on and extinguishesafterapproximately sixseconds
indicating satisfactory completion of the
pretensioner and airbag system self tests.

6.6.24.1
Pretensioner Assembly Renew
Read the warnings given in system fault strategy
and service i nstruaions on the previous page before
starting the following procedure.

1.

2.

4.

Procedure
Motor the drivers seat to its rearmost position.
Disconnect the battery ground (black) lead and
wait at least 10 minutes for the pretensioner power
supply to fully discharge before working on the
pretensioner system.
Note: Disconnect the battery within 12 seconds of
switchingoffthe ignition to avoid the alarm siren sounding.
Remove the pretensioner trim cover. Unbolt the
drivers seat. Tip the seat rearwards and disconnect
the seat and pretensioner squib connectors.
Release one bolt at the
base
of the seat belt
stal k
and
remove the pretensioner assembly.
Ensure that the safety clip is fitted to the connector
at the pretensioner squib. Fit the new assembly,
locating the anti-rotation peg into the rear hole of
the mounting bracket. Secure the assembly with
one bolt. Torque the bolt to 35Nm.
Safety Clip in place
5. Route the pretensioner lead between the seat and
the frame. Reconnect the seat and pretensioner
connectors. Ensure that the pretensioner connector
safety clip is secured. Refit the drivers seat and
loosely secure.
6. Reconnect the battery ground (black)
lead.

Note:
The
vehicle clock and
the
window control unit will
need
resetting
after completion of this procedure.
7. Switch on the ignition and check that the airbag
warn i ng I ight comes on when the ignition
is
switched
on and extingu
ishes
after approximately six seconds
indicating satisfactory completion of the
pretensioner and airbag system self tests.
8. Fit the front screws ensuring a 1.2mm gap between
screws and slide. Power the seat forwardTorque the
rear screws to 25 Nm. Power the seat backward.
Torque the front screws to 25 Nm.
September 1996 6-103

^=2?
Air Conditioning
System Trouble Shooting
System Trouble Shooting
There are five basic symptoms associated with air conditioning fault diagnosis. It is very important to identify the area of
concern before starting a rectification procedure. Spend time with your customer on problem identification, and use the
following trouble shooting guide.
The following conditions are not in order of priority.
No Cooling

1.
Is the electrical circuit to the compressor clutch functional?

2.
Is the electrical circuit to the blower motor(s) functional?
3. Slack or broken compressor drive belt.

4.
Compressor partially or completely seized.
5. Compressor shaft seal leak (see 9).
6. Compressor valve or piston damag^ (may be indicated by small variation between HIGH & LOW side pressures
relative to engine speed).
7. Broken refrigerant pipe (causing total loss of refrigerant).
8. Leak in system (causing total loss of refrigerant).
9. Blocked filter in the receiver drier.

10.
Evaporator sensor disconnected?

11.
Dual pressure switch faulty?
Note:
Should a
leak or low
refrigerant be established as
the
cause,
follow
the procedures
for
Recovery-Recycle
-Recharge,
and
observe all refrigerant and oil handling instructions.
insufficient Cooing

1.
Blower motor(s) sluggish.

2.
Restricted blower inlet or outlet passage
3. Blocked or partially restricted condenser matrix or fins.

4.
Blocked or partially restricted evaporator matrix.
5. Blocked or partially restricted filter in the receiver drier.
6. Blocked or partially restricted expansion valve.
7. Partially collapsed flexible pipe.
8. Expansion valve temperature sensor faulty (this sensor is integral with valve and is not serviceable).
9. Excessive moisture in the system.

10.
Air in the system.

11.
Low refrigerant charge.
May 1996 8-17

Air Conditioning
System Fault Diagnosis ^=2?
System Fault Diagnosis
Probable causes of faults can be found by comparing actual system pressures, registered on the manifold gauge set
or recovery-recharge-recycie station, and the pressure to temperature relationship graphs found on the previous

page.
The chart below shows the interpretation that may be made by this difference. The 'Normal' condition is that
which is relevant to the prevailing ambient and evaporator temperatures.
Note: If erratic or
unusual gauge movements
are experienced, check the equipment
against a
known manifold
gauge
set.

Low Side
Normal
Gauge
Normal to low
Low
Low
Low
Low
High
High
High Side Gauge
Normal
Normal
Low
Low
Low
Normal to high
Low
High
High
Fault Finding
High
Symptom
Discharge air initially cool
then warms up
As above
Discharge air slightly cool
Discharge air warm
Discharge air slightly cool or
frost build up at expansion
valve
Discharge air slightly cool
Compressor noisy
Discharge air warm and high
side pipes hot
Discharge air warm
Sweating or frost at evaporator
Diagnosis
Moisture in system
As above
HFC 134A charge low
HFC 134A charge very low
Expansion valve stuck closed
Restriction in High side of system
Defective reed valve
HFC 134A charge high or
condenser malfunction
Expansion valve stuck open
Caution:
The microprocessor is extremely sensitive
and should only
be tested
using
a
digital multimeter with no
less
than a 3.5
digit display and a
resistance
of no
less than
2 M
ohms.
The use
of any other form of multimeter will
damage the microprocessor

irreparably.
Note: Always allow time for the
servo
motors and blower motors to come to a
rest
before starting a
check.

The car should be in a workshop and the ambient
temperature
should
be
stable
e.g.
24''C
(75°F)
for at
least
30 minutes before
commencing the automatic
check.

At 24°C the
sensor
voltage is
2.972
V
± 2 mV.
The
rate of
change
is lOmVper
1
°C.

Unless
stated
otherwise,
all
checks
are carried out at the ECM
test plugs

Mode Switch: Off Ignition Switch: Aux 2
Signal Pin No.
Battery supply 1
Recirc input 9
Earth-ground 2
Earth-ground 6
Earth-ground 10
Earth-ground 38
Earth-ground 45
From mode switch 44
To mode switch 12
Voltage
n to 14v
0to2V
0 to 40mV
0 to 40mV
0 to 40mV
0 to 40mV
0 to 40mV
0 to 12V
10 to 13.3V
8-30 May 1996

Air Conditioning
Refrigerant Recovery and Recycling ^=2?
Recovery Procedure
Hote:
Run the
air-conditioning
system
for
a
few
minutes
before starting the
recovery
procedure as
this will
enable

more refrigerant to be recovered. Turn the
system
off
before
starting
the procedure.

1.
Attach the red (high side) hose oftheunittothe high
side fitting of the system on the vehicle then fit the
blue (low side) fitting to the low side on the vehicle.
Note: Make sure that the Air conditioning
system
has
pressure in it before beginning the recovery
process;
if
there is no
system
pressure there is no refrigerant to

recover.
Also
make sure that the
oil
drain
valve
is
closed.

2. Open both the high and low side valves on the
control panel.
3. Open the red CAS (vapour) valve and the blue
LIQUID valve on the tank.

4.
Turn on the MAIN POWER switch.
5. Press the RECOVERY key on the key-pad. The
display shows that the unit in the RECOVER mode
and AUTOMATIC cycle. After the compressor starts
the display shows the weight of refrigerant being

recovered.
The compressor shuts off automatically
when the recovery is complete and the display
shows the message 'CPL' and the final weight of the
recovered refrigerant.
6. Wait for five minutes and watch the manifold
gauges for a rise above 0. If a rise occurs press the
HOLD/CONT key. Repeat as needed until the
system pressure holds for two minutes.
Note: Drain the oil
separator
after
each
job.
7. Slowly open the oil drain valve and drain the oil
into the oil catch bottle. When all the recovered oil
has completely drained close the valve.
8. Replace oil lost during the recovery procedure by
measuringthe amount of oil inthe catch bottle and
adding the same amount of new oil to the system.
Note:
Dispose
of the
recovered
oil in an approved way.
9. When the recovery tank is full the compressor is
shut off and the display shows the message FULL.
Evacuating and Recycling the Refrigerant

1.
Open the red (high side) and the blue (low side)
valves on the unit and open the red GAS (vapour)
valve and the blue LIQUID valve on the tank.

2.
Enter the required time using the key-pad, press
enter,thedisplayshowstheenteredtime in minutes.
3. Start the vacuum pump by pressing the VACUUM
KEY again. The recycling process begins
approximately five seconds after the vacuum pump
starts and the message RECYCLE is displayed.
Note: If the vacuum pump
has
run for ten hours or
over

without an oil change the
message
OIL
flashes
on the
display.
Change
the pump oil and
then press
the
SHIFT/

RESET key and
the
zero key to
reset the
oil
change
timer
to zero.
The digital display counts down the evacuation

time.

4.
Check for non-condensibles after five minutes

recycling.
Ifthegauge needles are more than lOpsi
apart purge the non-condensibles from the tank by
open
i ng
the purge valve on the back of the
un
it and
continue to bleed until both needles show the same

reading.

The vacuum sequence continues until the
programmed time has elapsed at which point the
message CPL is displayed.
5. If the moisture indicator turns green recharge with
refrigerant.
or
5. If the moisture indicator has not turned green
replace the unit's filter-drier, which is probably

saturated.

Note:
Pressing
any key at this point allows the next
function to be
accessed.

To recycle the refrigerant only without pulling a
vacuum for an indefinite period of time press the
SHIFT/RESET key and the RECYCLE key on the key­

pad.
Press the SHIFT/RESET key to cancel.
For vacuum only press the SHIFT/RESET key and
the ENTER key and then press
"1".
Run the vacuum
pump as long as required and then press
"1"
or
press SHIFT/RESET to cancel.
8-48 May 1996