1997 ASTON MARTIN DB7 Workshop Manual

5^^?
Electrics
Seat Belt Pretensioner
The Seat Belt Pretensioner System (where fitted)
Description
The DB7 seat belt pretensioner system operates the drivers seat belt pretensioner in conjunction with the Airbag

system.
The seat belt pretensioner control module is located under the right hand seat, beside the right hand seat
control module.
The pretensioner control module calculates changes in vehicle speed using an input signal from an accelerometer.
When a collision is detected (Rapid reduction in vehicle speed) and the safing sensor in the airbag system is also

activated,
the pretensioner charge
is
fi red usingelectrical energy stored in a capacitor within the pretensioner control
module. Firing of the pretensioner charge applies additional tension to the drivers seat belt.
The airbag and seat belt pretensioner systems share the SRS (Airbag) warning lamp. Any fault detected by the
pretensioner control module is indicated by constant illumination ofthe
SRS
(Airbag) warning lamp. Flashing of the
SRS warning lamp indicates a fault in the airbag system.
Should both systems develop faults, the pretensioner system will permanently illuminate the warning lamp. This
would mask the airbag system warning indication. Therefore, rectify the pretensioner fault and then retest for faults
in the airbag system
The pretensioner control module can log up to 10 diagnostic trouble codes together with a time since each fault was
alerted to the driver. Each
fau It
wi
11
be identified as 'Permanent' or 'Intermittent' on the PDU diagnostic trouble codes

screen.

System Connections
DB7 is fitted with an Autoliv ECS or RC5 Pretensioner Control Module. The Pretensioner Control Module has an 18
pin connector featuring six shorting bridges. The mating halves of the connector may be securely locked using a
double mechanical locking system.
The following pins on the control module connector are used in the Aston Martin seat belt pretensioner system:
Pin 1 Ground
' ' "L Pin 2 Airbag Warning Lamp
Pin 11 Drivers airbag positive
Pin 12 Drivers airbag negative
Pin 14 Serial communications
Pin 15 12 volt positive feed
Case Ground

15.
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16 illn
^
Note: Pins
1
-2, 3 -4, 5 -6, 7 -8,9 -
10
and 11-12
are
shorted
together
by internal shorting links within the connector when
it
is
disconnected.
The
short circuits may
be
temporarily
overcome
for fault analysis
purposes
by inserting
a
suitable non-metallic

cheater
(the
sBfTiG
size
3s
the
p€gs
in the controller connector) into the rectsngul^r hole opposite the relevsnt p3ir of pins.
September 1996 6-101

Electrics //—>> ^^^^^^ • >^
Seat Belt Pretensioner I'•—
-"i-t.
^-^
JH—X

System Fault Strategy
No single fault may cause an unexpected deployment. The controller will supervise the pretensioner electrical
system in order to warn the driver should a fault occur. Any fault detected by the self diagnostics shall cause the SRS/
airbag warning lamp to be activated, and in some cases the pretensioner control module to enter shutdown mode.
In shutdown mode, the energy of the reserve capacitors shall be discharged to avoid unintended deployment.
As the ignition is switched on, the pretensioner controller will directly discharge the energy capacitors. When the
start up procedure is completed without detecting any faults, the DC/DC converter will be activated allowing the
capacitors to be charged. The system shall be fully active within
11
secondsafterswitchingthe ignition on providing
that no faults are detected.
All system faults monitored by the controller are filtered in software to avoid fault warnings due to transient electrical
disturbances.
If a fault which could lead to inadvertent deployment is detected by the microprocessor, a software shutdown will
be generated. However, a leakage to an earth or positive potential in the pretensioner output circuit shall not cause
the controller to enter shutdown mode.
If a permanent short of the ignition transistor occurs, a shutdown shall be generated by the hardware circuit. If a
shutdown occurs, the system shall be unable to deploy the pretensioner after a period of 3 seconds (i.e. capacitors
discharged to under minimum deployment voltage).
WARNING: To avoid the possibility of personal injury caused by accidental deployment of the pretensioner,
disconnect the vehicle battery and wait at least 10 minutes for all voltages to fully discharge before working on
the pretensioner
system.
This
covers the possibility of the normal capacitor discharge circuits being inoperative
and failing to discharge the capacitor when instructed to do so.
WA RNING: Do not make any electrical measurements on the pretensioner squib. Electrical measurement devices
can induce sufficient voltage to cause unintentional firing of the pretensioner assembly
If the module enters shutdown mode, all diagnostic functions are stopped, but the communications link remains

active.
A fault code corresponding to the cause of the problem may be read by the PDU.
Assembly/Removal/Service I nstructions
WARNING: In the event of a vehicle impact where the airbags and the seatbelt pretensioner (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.

Vehicles for the North American, Australian and Japanese markets are fitted with drivers seat belt pretensioner
systems and are fitted with a shorting plug in the yellow connector adjacent to the pretensioner control module.
Vehicles for other markets do not have drivers seat belt pretensioners fitted but have a blanking plug in the yellow
connector adjacent to the pretensioner control module.
6-102 September 1996

'^^
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

Etectrics
Seat Belt Pretensioner
Seat Belt Pretensioner Circuits
Seat Belt
Pretensioner
Module
1 o
2 O-
3 O
4 O
5 o
6o
70
80
9 O
10 o
n o-
12 O-
13o
14 O-
15 O-
Ground
c
r-1 B
> Warning
Lamp
'' Shorting
YK 2 Plug
Connector
Shorting
Links
/
/ PW
BW
3
1
O
2 1 (
LGS 1
3
YK
2
Instrument
Pack
, PCB
Squib

)

Lower
OBDII
^ Diagnostic
Socket
Air bag
* Diagnostic
Monitor
6-104 September 1996

^^
Electrics
Seat Belt 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 sv^^itch
0D1
E
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
Seat Beit Pretensioner Diagnostics
WARNING: To avoid the possibility of personal
injury caused by accidental deployment of the
pretensioner, disconnect the vehicle battery and
iva/f at least 10 minutes for all voltages to fully
discharge before working on the pretensioner
system. This covers the possibility of the normal
capacitor discharge circuits being inoperative and
failing to discharge the capacitor when instructed
to do
so.

WARNING: Do not make any electrical
measurements on the pretensioner
squib.
Electrical
measurement devices
can
induce sufficient voltage
to cause unintentional firing of the pretensioner
assembly
050 A Pretensioner Squib Leak to Battery
Positive
050A will be logged if the resistance of the
pretensioner squib feed or return line to a positive
potential falls below
1
k£2.
Procedure

1.
Read the warnings given at the start of this
pretensioner diagnostics section.

2.
Connect the PDU to the lower diagnostic socket
and access the pretensioner control module. Verify
that an 050A code is logged and note if the fault is
shown as intermittent. Note any other codes in the
DTC log and then clear all codes.
3. Switch off the ignition and wait at least 10 minutes
for the pretensioner squib firing capacitors to fully
discharge before continuing with this procedure.

4.
Disconnect the pretensioner squib connector at the
rearward harness. Disconnect the pretensioner
control module and temporarily cheat the squib
shorting link.
Note: The control module harness connector has a

shorting
link which short circuits
the
squib
lines together

when the connector is displaced. Carefully insert a

suitable non-metallic cheater to remove the short
circuit
between pins 11 and 12 before continuing with fault
diagnosis.

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I
ooo
Inserr cheater here
September 1996 6-105

Electrics
Seat Belt Pretensioner 5^^?
Switch on the ignition and check for a positive
potential on the squib feed or return lines at the two
pins of the squib harness connector (activating
circuits in the rearward harness in turn may assist in
identifyingthe voltage
source).
Ifa positive potential
is detected, switch off and repair the circuit fault.
If no short circuit is detected in the rearward
harness, go to step 6.
With the ignition switched off and the pretensioner
squib disconnected, check the squib harness for
physical damage.
If any damage is detected, replace the complete
pretensioner squib assembly.
If no damage is detected, the fault is possibly in the
pretensioner control module. Replace the control
module.
Remove the cheater from the control module
connector.
'o o 0080 000000000' 000 ™ ^^ ^^^
ir Insert cheater here
Reconnect all components. Switch on the ignition
and test the vehicle to ensure that the problem is

resolved.

050B Pretensioner
Squib
Leakto Ground
050B will be logged if the resistance of the
pretensioner squib feed or return line to ground
falls below
Ikfi.

Procedure

1.
Read the warnings given at the start of this
pretensioner diagnostics section.

2.
Connect the PDU to the lower diagnostic socket
and access the pretensioner control module. Verify
that an 050B code is logged and note if the fault is
shown as intermittent. Note any other codes in the
DTC log and then clear all codes.
3. Switch offthe ignition and wait at least 10 minutes
for the pretensioner squib firing capacitors to fully
discharge before continuing with this procedure.

4.
Disconnect the pretensioner squib connector at the
rearward harness. Disconnect the pretensioner
control module and temporarily cheat the squib
shorting link.
Note: The control module harness connector has a
shorting link which
short
circuits
the squib lines together

when the connector is displaced. Carefully insert a

suitable non-metallic cheater to remove the
short circuit
between pins 11 and 12 before continuing with fault
diagnosis.

'o
o 00 8 o 000000000' 000
Insert cheater here
Check for a short circuit to vehicle ground on the
squib feed or return lines at the two pins of the squib
harness connector. If a short circuit is detected,
switch off and repair the circuit fault.
If no short circuit is detected in the rearward
harness, go to step 6.
With the ignition switched off and the pretensioner
squib disconnected, check the squib harness for
physical damage.
If any damage is detected, replace the complete
pretensioner squib assembly.
If no damage is detected, the fault is possibly in the
pretensioner control module. Replace the control
module.
Remove the cheater from the control module
connector. Reconnect all components. Switch on
the ignition and test the vehicle to ensure that the
problem is resolved.
6-106 September 1996

D=27
Electrics
Seat Belt Pretensioner
050C Pretensioner Squib High Resistance 050D Pretensioner squib low resistance
050C will be logged if the resistance of the
pretensioner squib circuit rises above 4.5 ±0.5C2
050D will be logged if the resistance of the
pretensioner squib circuit falls below 1.4 ±0.4Q
Procedure
Read the warnings given at the start of this
pretensioner diagnostics section.
Connect the PDU to the lower diagnostic socket
and access the pretensioner control module. Verify
that an 050C code is logged and note if the fault is
shown as internnittent. Note any other codes in the
DTC log and then clear ail codes.
Switch off the ignition and wait at least 10 minutes
for the pretensioner squib firing capacitors to fully
discharge before continuing with this procedure.
Disconnect the pretensioner squib connector at the
rearward harness. Disconnect the pretensioner
control module and temporarily cheat the squib
shorting link.
3.
Procedure
Read the warnings given at the start of this
pretensioner diagnostics section.
Connect the PDU to the lower diagnostic socket
and accessthe pretensioner control module. Verify
that an 050D code is logged and note if the fault is
shown as intermittent. Note any other codes in the
DTC log and then clear all codes.
Switch off the ignition and wait at least 10 minutes
for the pretensioner squib firing capacitors to fully
discharge before continuing with this procedure.
Disconnect the pretensioner squib connector atthe
rearward harness. Disconnect the pretensioner
control module and temporarily cheat the squib
shorting link.
Note: The control module harness connector has a
shorting link which
short
circuits the squib
lines together

when the connector is displaced. Carefully insert a
suitable non-metallic
cheater to
remove
the short
circuit
between pins 11 and 12 before continuing with fault
diagnosis.
.j^ 'o o ob bo oooooooo
O O O
iV ^3 ^3 ^3 ^3 ^3 ^
lU Insert cheater here
Check the continuity of the squib feed and return

lines.
If any significant resistance is measured,
service the wiring as necessary.
Also check the condition of the connector pins for
damage or lack of tension and service
as
necessary.
If the circuit resistance is acceptable and the
connector pins are good, go to step 6.
If any defects are identified and serviced, go to step
7.
If the checks in step 4 are good, the high circuit
resistance must be in the pretensioner squib or in
thecontrol module. Replace the pretensioner squib
and reconnect all components.
Clearall logged DTCs from the pretensioner control
module and then test the vehicle.
If the 050C code is logged again, replace the
control module.
Note: The control module harness connector has a
shorting link which
short
circuits the squib
lines together

when the connector is displaced. Carefully insert a
suitable non-metallic
cheater to remove the
short circuit
between pins 11 and 12 before continuing with fault
diagnosis.
Insert cheater here
Check the continuity from the squib feed line to the
squib return line. With the shorting link cheated,
the resistance should be more than lOkQ. If the
resistance is less than 10kQ, service the wiring as
necessary.
Also check the connector pins for any damage
which could cause an unintentional short circuit.
If the checks in step 5 are good, the low circuit
resistance must be in the pretensioner squib or in
thecontrol module. Replace the pretensioner squib
and reconnect all components.
Clearall logged DTCs from the pretensioner control
module and then test the vehicle.
If the 050D code is logged again, replace the
control module.
September 1996 6-107

Electrics
Seat Belt Pretensioner ^?
060C Warning Lamp Short Circuit
060C will be logged if the nnonitor current flow
through the SRS/Airbag warning lamp is excessive.
The warning lamp circuit is normally at 12 volts and
is switched to ground by the airbag control module
or by the pretensioner control module when one of
these control modules detects a fault.
If either control module connector is displaced and
the ignition is switched on, the warning lamp will
be illuminated via the ground shorting link between

pins!
and 2 ofthe pretensioner controller connector
or pins 4 and 5 of the airbag controller connector,
both control modules must be checked for the
appropriate DTC to isolate which circuit is at fault.
Procedure

1.
Connect the PDU to the lower diagnostic socket
and access the pretensioner control module. Verify
that an 060C code is logged and note if the fault is
shown as intermittent. Note any other codes in the
DTC log and then clear all codes. Go to step 2.
If fault code 060C is not logged, go to the diagnostics
section of the airbag system.

2.
Check the security of the pretensioner control
module connector.
If the connector is secure, go to step 3.
If the connector isdisplaced,resecu re theconnector.
Clear all logged DTCs and retest the vehicle to
ensure that the problem is resolved.
3. Access the SRS/Airbag warning lamp and check the
lamp resistance.
If the resistance is approximately
120£2,
the lamp is

good.
Refit the lamp and go to step 4.
If the resistance of the lamp is significantly less than
approximately 120^, fit a new lamp and refit the
instrument panel. Clear the logged DTCs from the
pretensioner control module and retest the vehicle
to ensure that the problem is resolved.

4.
If the checks in step 3 are good, the low circuit
resistance must be in the instrument pack or in the
control module. Replace the pretensioner control
module and reconnect all components.
6. Switch on the ignition and then test the vehicle.
If the 060C code is logged again, replace the
instrument pack.
060D Warning lamp open circuit
060D will be logged if the monitor current flow
through the SRS/Airbag warning lamp is below the
normal monitor level.
The warning lampcircuit is normally at 12 voltsand
is switched to ground by the airbag control module
or by the pretensioner control module when one of
these control modules detects a fault.
Procedure
Connect the PDU to the lower diagnostic socket
and access the pretensioner control module. Verify
that an 060D code is logged and note if the fault is
shown as intermittent. Note any other codes in the
DTC log and then clear all codes. Go to step 2.
lffaultcode060D is not
logged,
gotothediagnostics
section of the airbag system.
Switch off the ignition. Access the SRS/Airbag
warning lamp and check the lamp resistance. The
resistance should be approximately 120Q.
If the resistance is 120i2, go to step 3.
If the lamp resistance is significantly lower than

120^2,
replace the lamp. Retest the vehicle to
ensure that the problem is resolved.
Wait 10 minutes after switching off the ignition to
ensure that the pretensioner firing capacitors have
fully discharged.
Disconnect the pretensioner control module and
temporarily cheat the warning lamp shorting link.
Note: The control module harness connector has a
shorting link which short circuits the warning lamp line
(pin 2)to ground
(pin
Dwhen
the
connector
is
displaced.
Carefully insert a suitable non-metallic cheater to remove
the
short
circuit
between
pins
1
and 2 before continuing
with fault
diagnosis.

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i^i
^ ^ ^ 1^1
Insert cheater hare
6-108
September
1996