sensor ASTON MARTIN DB7 1997 Service Manual

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
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.

i"o
o o b 6 o ooooooooo'
I
ooo
Inserr cheater here
September 1996 6-105

Electrics
Seat Belt Pretensioner
Check the continuity of
the
line from pretensioner
control module pin 2 to instrument pack green
connector pin 2.
If continuity is approximately
OQ,
go to step 5.
If the line resistance
is
significantly greater
than
OQ,
service the wiring as necessary. Reconnect all
components and test the vehicle to ensure that the
problem is resolved.
Ifthe lamp
and
wiring
checks are
good,
the
fault lies
in the instrument pack or in the control module.
Replace the control module and retest. Ifthe fault
persists, replace the instrument
pack.
Reconnectall
components and test the vehicle to ensure that the
problem is resolved.
Pretensioner Control Module Internal
Faults
The following codes indicate internal faults within the
pretensioner control module.
0209 Safing sensor error
030A Temperature sensor error
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
Acceierometer offset
OAOC Analogue voltage error
090A EEPROM not programmed
0909 EEPROM checksum
090C RAM check error
060E Warning lamp driver error
0A09 Communications error
OAOA External watchdog error
OAOB External watchdog time out
020A Safing sensor not closed
If any of the above codes are logged, replace the
pretensioner control module.
September 1996 6-109

in:!M3^^?
Air Conditioning
Contents
Contents
General Description 8-5
Specifications 8-5
Climate Control System 8-6
System Description 8-7
Special Servicing Tools and Equipment 8-7
Working Practices 8-8
General 8-8
Handling Refrigerant 8-8
Handling Lubricating Oil 8-8
System Maintenance 8-8
Temperature Distribution System 8-9
Fan Speed Control (Mode Switch) 8-10
Face Level Temperature Differential 8-10
Temperature Rotary Control 8-10
Refrigeration Cycle 8-11
System Protection 8-12
General System Procedures 8-12
Leak Test 8-12
Charge Recovery (System Depressurisation) 8-12
Evacuating the System 8-13
Adding Compressor Lubricating Oil 8-13
Adding Refrigerant 8-14
Functional Check 8-15
System Trouble Shooting 8-1 7
Electronic Control Module (ECM) 8-19
In Car Controls 8-21
Temperature Demand Switch 8-21
Face Level Differential Controller 8-21
Air Conditioning Function Switch 8-22
Fan Speed Control Switch (Mode Switch) 8-23
Temperature Sensors 8-23
Evaporator Sensor 8-24
Motorised In-Car Aspirated Sensor 8-24
Water Temperature Switch 8-25
Blower Motors 8-25
Potentiometers 8-26
Servo Motors 8-27
Vacuum System 8-28
Pressure-Temperature Graphs 8-29
May 1996 8-1

^7
Air Conditioning
Contents
Repair Procedures
8.1.01.1 Compressor Removal/Renewal 8-51
8.1.02.1 Field Coil Renewal 8-52
8.1.03.1 Renew Gasket Kit 8-52
8.1.04.1 Valve Plate Renewal 8-53
8.1.05.1 Expansion Valve Renewal 8-54
8.1.06.1 Hose-Compressor to Evaporator Renewal 8-55
8.2.01.1 Air Conditioning Unit Renewal 8-55
8.2.02.1 Evaporator Unit Renewal 8-56
8.2.03.1 Upper Servo Feedback Potentiometer Renewal 8-57
8.2.04.1 Lower Servo Feedback Potentiometer Renew 8-57
8.2.05.1 Upper Flap Motor Assembly Renew 8-58
8.2.06.1 Lower Flap Motor Assembly Renew 8-58
8.2.07.1 Ambient Temperature Sensor Renew 8-59
8.2.08.1 Blower Motor Driver Side Renewal 8-59
8.2.09.1 Blower Motor Passenger Side Renewal 8-59
8.2.10.1 Blower Assembly Driver/Passenger Side Overhaul 8-60
8.2.11.1 Blower Motor High Speed Relay Renewal 8-61
8.2.12.1 Water Temperature Switch Renewal 8-62
8.2.13.1 Heater Matrix Renewal 8-62
8.2.14.1 Electronic Control Module Renew 8-63
8.3.01.1 Vacuum System Solenoid Renewal 8-63
May 1996 8-3

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Air Conditioning
System Description
System Description
The in-car temperature and humidity are regulated by the electronically controlled air conditioning system. The
system comprises four subsystems:
• heater matrix, supplied with water from the engine cooling system
• refrigeration
• vacuum
• electronic control
Apart from the ambient temperature sensor and the aspirated in-car temperature sensor, most of the components
are housed in the air conditioning unit (Fig. 1) situated behind the dash board, or in the engine compartment.
Figure 1.
Key to Fig. 1 - Left Hand Air Conditioning Unit

1.
Upper feedback potentiometer

2.
Water temperature switch
3. Lower feedback potentiometer

4.
Vacuum valve block
5. Vacuum restrictor
6. Condensate drain tube
Figure 2.
Key to Fig. 2 - Right Hand Air Conditioning Unit

1.
Upper servo motor

2.
Electronic control module
3. Lower servo motor

4.
Evaporator sensor
5. Condensate drain tube
Special Servicing Tools and Equipment
1 PDU system
1 Charging station
1 Leak detector
1 Temperature test box
1 Sanden compressor service tool kit
1 CM Type compressor service tool kit
1 Digital voltmeter
1 Multimeter
May 1996 8-7

Air Conditioning
Temperature Distribution System
The Control Panel (Fig. 4) contains:
• Fan speed-defrost rotary switch (Mode-Switch),
• Air Conditioning Function Switch
• Temperature differential rotary control
• Temperature rotary control,
The control panel relays information to the ECM.
Figure 4.
Fan Speed Control (Mode Switch)
The rotary switch controls airflow from the blower motors. The switch has five positions: 3C, 1, 2,3 and DEFROST.
«» The system is not operational; a residual signal is sent to the Electronic Control Module (ECM)
to ensure that the blower flaps are closed to prevent outside air from entering the system.

1,
2,3 Selection information is relayed to the ECM. Signals are also relayed to the ECM from the
temperature selector feedback circuits and various sensors. Fan speed is steplessly controlled
by the ECM, within the ranges 1, 2 and 3.
DEFROST the fans operate at maximum speed, front screen vents open fully, lower flaps close fully and
maximum output is directed to the windscreen (there may be a delay of up to 30 seconds from
selection to execution of this function).
Face Level Temperature Differential
This control is used to vary the temperature difference between the air coming through the face vents and that coming
through the lower vents into the footwell.
Temperature Rotary Control
This is used to preset the in car heat level in either automatic or manual mode. There are three temperature sensors
located in the system:
• Exterior ambient
• In-car
• Evaporator.
An input voltage is supplied to the sensors from AC4-13 of the control module. The temperature sensing signal from
the sensors is transmitted to the control module via AC4-4 and AC2-4 respectively. The sensors are semiconductor
devices which provide a voltage output proportional to the sensed temperature.
8-10 May 1996

^7
Air Conditioning
Temperature Distribution System
Air Conditioning Function Switch
When AC, DEM or Re-circulation ^v is selected the system engages the Air conditioning compressor using the
electromagnetic clutch. The in-car temperature is automatically corrected to the pre selected level by the system
sensors.
When MAN (manual mode) is selected it provides the operator selection of fan speed and in-car temperature
selection facilities. The in-car temperature is not thermostatically corrected to a predetermined level by the system
sensors.
When ECO is selected the system is in economy mode which allows the fan speed and heating levels to be selected
but gives no cooling. The air conditioning compressor is not engaged putting a minimum load on the engine.
When manual re-circulation is selected the blower flaps are closed and only that air which is in the vehicle is re­

circulated.
When the ignition is turned off the blower flaps revert to the fresh air position.
Refrigeration Cycle
The Compressor draws low pressure refrigerant from the evaporator and by compression, raises refrigerant
temperature and pressure. High pressure, hot vaporised refrigerant enters the Condenser where it is cooled by the
flow of ambient air. A change of state occurs as the refrigerant cools in the condenser and it becomes a reduced
temperature high pressure liquid.
Figure 5.

1.

2.

3.
Compressor
Condenser
Receiver-Drier

4.
Expansion Valve
5. Evaporator
6. Triple Pressure Switch (Trinary switch)
May 1996 8-11

^=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
/J=y>f^^^
—p )
System Trouble Shooting

12.
Compressor clutch slipping.

13.
Blower flaps or distribution vents closed or partially seized.

14.
Water valve not closed.

15.
Evaporator sensor detached from evaporator.
Intermittent Cooling
Is the electrical circuit to the compressor clutch consistent?

2.
Is the electrical circuit to the blower motor(s) consistent?
3. Compressor clutch slipping.

4.
Faulty air distribution flap potentiometer or motor.
5. Motorised in-car aspirator or evaporator temperature sensor faulty, causing temperature variations.
6. Blocked or partially restricted evaporator or condenser.
Noisy System

1.
Loose or damaged compressor drive belt.

2.
Loose or damaged compressor mountings.
3. Compressor oil level low, look for evidence of leakage.

4.
Compressor damage caused by low oil level or internal debris.
5. Blower(s) motor(s) noisy.
6. Excessive refrigerant charge, witnessed by vibration and 'thumping' in the high pressure line (may be indicated by
high HIGH & high LOW side pressures).
7. Low refrigerant charge causing 'hissing' at the expansion valve (may be indicated by low HIGH side pressure).
8. Excessive moisture in the system causing expansion valve noise.

Note;
Electrical faults
may
be more rapidly traced using PDU.
Insufficient Heating

1.
Water valve stuck in the closed position.

2.
Motorised in-car aspirator seized.
3. Blend flaps stuck or seized.

4.
Blocked or restricted blower inlet or outlet.
5. Low coolant level.
6. Blower fan speed low.
7. Coolant thermostat faulty or seized open.
8-18 May 1996