battery ASTON MARTIN DB7 1997 Owner's Guide

Electrics
Airbag System =2?
Airbag DM Fault Code 24
Safing sensor output - battery feed/return open
circuit.
Normal Operation
The diagnostic module measures the voltage on
diagnostic module pins 2-5 and 2-6 the voltage
varies with the vehicle charge level
as
shown in the
table below:
in 2-5
2.3V
2.4 V
2.5V
2.7V
2.8V
3.0V
3.1V
3.2V
3.4V
3.5V
3.7V
3.8V
4.0V
4.1V
4.3V
Pin 2-6
2.3V
2.4V
2.5V
2.7V
2.8V
3.0V
3.1V
3.2V
3.4V
3.5V
3.7V
3.8V
4.0V
4.1V
4.3V
Cliarge Volts
9.0V
9.5V
10.0V
10.5V
11.0V
11.5V
12.0V
12.5V
13.0V
13.5V
14.0V
14.5V
15.0V
15.5V
16.0V
The diagnostic module also measures the voltage at
pin 1-7 (battery input). Using the battery input
voltage, the system can predict the expected voltage
level on pins 2-5 and 2-6. If the voltage on pins 2-
5 or 2-6 is higher or lower than expected, a fault
code 24 will be declared.
Possible Causes
• Open circuit or high resistance in the wiring
harness or safing sensor.
• Intermittent battery voltage on pin 1-7
• The resistance of the pin 2-5 to 2-6 circuit to

ground.
This circuit should be open to ground at
all times.
Fault Analysis
WARNING: Read and adhere to all warnings and
safety procedures at the start of
this
section when
working on the airbag system.

1.
Disarm the airbag system and fit airbag simulators
(6.4.21.4).

2.
Probe the battery input voltage terminal
1
-7. Start
the engine and monitor the charge voltage level
using a digital multimeter. Run the engine at idle
speed and look for any instability in the voltage

level.
Run the engine at a constant medium speed
and then at a constant high speed and repeat the
observation for voltage instability.
If the voltage levels are stable, go to step 3.
If instability of the voltage level is observed,
Investigate and rectify the problem in the charging
circuit.
3. Switch off the ignition. Disconnect the diagnostic
module and check for OQ continuity from pins 2-5
to 2-6.
If no resistance is detected, go to step 4.
If any resistance is detected between pins 2-5 and

2-6,
service the wiring or safing sensor to achieve
Ofi continuity.

4.
Measure the resistance to ground from pins 2-5 and

2-6.

If no short circuit is detected, replace the diagnostic
monitor. Rearm the airbags (6.4.21.4).
If
a
short to grou
nd
is detected, service the wiring or
safing sensor as necessary. Rearm the airbags
(6.4.21.4).
6-90 September 1996

Electrics
Airbag System ^?
Airbag DM Fault Code 51
Airbag diagnostic module - thermal fuse blown.
WARNING: The diagnostic module will blow the
internal fuse whenever a short circuit to ground
occurs in the deployment circuits. Itdoesnotblow
because of
excessive
current
flow.
The thermal
fuse is not a serviceable item. No attempt should
be made to replace or
bypass
the fuse.
WARNING: Do not install a new diagnostic
module until the short has been located and
corrected. A short which goes away before
corrective action has been taken must be regarded
asan intermittentfault. Installinga newdiagnostic
module when there is an intermittent fault will
result in repeated diagnostic module failures and
repeated repairs.
Fault Analysis
Disarm the airbag system and fit airbag simulators
(6.4.21.4).
Inspecttheconnectorsandterminalsfor any foreign
metal objects or damaged terminals which could
be the cause of the short circuit.
Check each of the circuits in the possible causes list
and isolate the intermittent short circuit. Rectify the
fault.
See the warnings above about replacement of
diagnostic modules when intermittent shorts are
present.
Replace the diagnostic module.
Reconnect all components and rearm the airbags
(6.4.21.4).
Normal Operation
In order to prevent airbag deployment in the event
of a short circuit to ground, the diagnostic module
blows its internal fuse as soon as a short to ground
is detected. This action removes all battery and
back-up power from the deployment circuits. The
diagnostic module will flag the higher priority
codes 13 or 14 while the short to ground exists. If
the short is intermittent and temporarily corrects
itself, the d iagnostic modu le wi
11
flag code
51.
If the
short to ground returns, the diagnostic module will
again flag the higher priority code 13 or 14 instead
of code 51.
Code 51 after Airbag Deployment
The internal wiring may be shorted to the metal
airbag housings after the airbags are deployed. The
diagnostic module will see this as a short to ground
in the deployment wiring, it will flagacode 14and
blow the internal fuse. As the deployed airbags

cool,
the short circuit may rectify itself. The
diagnostic module will then flag a code 51. This
intermittentfault must be investigated and corrected.
Possible Causes
A short circuit to ground in any of the following:
DM pins 2-2, 2-5 or 2-6 to the safing sensor
DM pins 2-2, 2-5 or 2-3 to the passenger airbag
DM pins 2-2, 2-4 or 2-5 to the drivers airbag
DM pins
1
-2 or
1 -11
to RH crash sensor
DM pins
1
-6 or
1
-12 to LH crash sensor
6-98 September 1996

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

^^
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

3-^?
Electrics
Seat Removal/Replacement 97.5 MY

6.6.03
Seat Removal 97.5 MY
Description
The 97.5 MY front seats are common to the DB7
Coupe
and
Volante
models.
Seat
switch
assembi ies

are located on the outboard side of both driver and
passenger
seats.
The front switch controls fore and
aft movement and the seat height adjustment. The
centre switch controls the recline adjustment. The

rear switch
controls
the
lumbar support adjustment.

The seat
heater switches are mounted on the centre
console, forward of the gear selector
lever.

Only one of
the
slide,
recline or height motors can
be driven under manual control at any one time.
Each seat switch pack is hard wired to the relevant

Seat Control
Module
beneath each
seat.
The
module
outputs are hard wired to the seat motors.
Removal
WARNING -
Seat
belt
Pretensioners
(if fitted):

To avoid the possibility
of
personal
injury
caused

by accidental deployment of the seat belt

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 detonator capacitor when
instructed
to
do
so.

Procedure

1.
Motortheseatto
its
maximum forward position and
remove the fixings at the rear of the slides.

2.
Motor the seat to its maximum rearward position
and remove the front seat slide fixings.
3. Disconnect the battery
ground
(black)
lead.
Wait at
least 10 minutes for the pretensioner power supply
to fully discharge before working on the seat if a
pretensioner is fitted.
Note: Disconnect the battery within 12 seconds of
switching off the ignition to avoid the alarm siren sounding.

4.
Disconnect the two harness connectors from the
seat control module. Also disconnect the yellow
connector from the pretensioner control module if
a pretensioner is fitted.
Figure 1. Control module connectors
5. Remove the tie straps and release the seat harness.
6. Remove the seat earth screw from the
sill.

7. Tip the seat forwards and remove from the vehicle.
Steps 10-12 Seat Belt Pretensioner vehicles only.
8. Remove the seat belt pretensioner cover (if fitted)
9. Disconnect the buckle fly-lead from the
pretensioner.

10.
Release
one
bolt at
the
base of the
seat
belt stalk and
remove the pretensioner assembly.
Reassembly and Replacement
Steps 1-3 Seat Belt Pretensioner vehicles only.

1.
Ensurethatthesafetyclipisfittedtothepretensioner
connector at the squib.

2.
Fit the assembly to the seat, locating the
anti-

rotation peg into the rear hole of the mounting

bracket.
Securethe
assembly with
one
bolttightened
to 35 Nm.
3. Route the pretensioner lead between the seat and

frame.
Refit the pretensioner
cover.

All vehicles

4.
Replace the seat in the vehicle. Reconnect and
secure the harnesses with tiestraps.
5. Reconnect the vehicle battery.
Note:
The vehicle clock and the window control units

will
need resetting after completion
of
this
procedure.

April 1997 6-127

Electrics
Seat Control Module Removal/Replacement 97.5 MY 'O "3^2?
Switch on the ignition and checi< that the airbag
warning lamp comes on when the ignition is
switched on and extinguishes after approximately
six seconds indicating satisfactory completion of
the pretensioner and airbag system self
tests.

Fit
the front
seat
retaining screws ensuring
a
1.2mm
gap between the screw heads
and
the
slides.
Power
the seat forward and refit the rear screws.
Caution:
Centralise the
rear
fixing holes
with the
body weld
nuts
prior to
inserting the
bolts.

Torque the rear screws to 25 Nm. Power the seat
backwards. Torque the front screws to 25 Nm.
Motor the seat through its full range of movement
to ensure correct
operation.

6.6.08
Seat Control Module 97.5 MY
Removal
WARNING -
Seat
belt
Pretensioners
(if
fitted):

To avoid the possibility
of
personal injury caused

by accidental deployment of the seat belt

pretensioner,
disconnect
the
vehicle battery and

wait at
least
10
minutes
for all
voltages
to fully

discharge
before
working
near the
pretensioner

system.
This covers
the
possibility
of
the
normal
capacitor
discharge circuits
being
inoperative and
failing to discharge the detonator capacitor when
instructed
to
do
so.

1.
Lower the door window and open the relevant
door. Disconnect
the
battery ground cableand wait
for 10 minutes if
a
pretensioner
is
fitted.
Otherwise,
proceed immediately to step 2.
(ei-SMiECu
Figure!.
Seat ECU Removal

2. Loosen two nuts securing the seat ECU. Slide the
ECU to the left and remove it from the front of the
seat.
3. Disconnect two connectors from the ECU.
Replacement

1.
Reconnect the two control module connectors. Fit

the seat control
moduleand
tighten
thetwo securing

nuts.

3. Reconnect the battery ground and test for correct
operation of the seat controls.
6-128 April 1997

^"^
Body and Trim
Body Repair
Precautions
Paint
Ensure that there is efficient ventilation at all times. Paint spraying should be confined to spray booths.
Anyone with a history asthma should not be engaged in any process which involves the use of isocyanates.
Any operator working inside a spray booth where isocyanates are present must use air-fed breathing equipment.
Supplied air to the visor should be fed at the recommended pressure and filtered to remove oil, water and fumes.
Operators involved in handling, mixing or spraying should wear protective clothing, gloves and goggles to avoid
skin and eye contact. A Paticle mask or canister typr respirator should be worn when sanding.
Applied heat
When welding, flame cutting or brazing and so on, goggles, a mask or fume extractor and flameproof protective
clothing should be used always.
It is especially important when working with polyurethane compounds to use air-fed breathing equipment.
Ensure that at all times the appropriate fire fighting equipment isavailableand that personnel are trained in its use.
Metal repair
Wear appropriate eye and hand protection when sanding, drilling, cutting, chiselling, flatting or welding. Wear a
face mask or air-fed visor when sanding or flatting either body solder or
fillers.
When a soldering operation has been

completed,
remove swarf from the work area and wash your hands thoroughly.
General Repair Notes
The following precautions should be noted before any work is carried out:
• disconnect the vehicle battery ground
lead,
taking note of the reconnection procedures
• Make sure that you have read and understood the safety related procedures in this section.
Caution:
Electric arc
welding must not
be
used on the
vehicle as the high
voltages produced by
this process
will
cause
irreparable

damage
to the electrical control and
microprocessor
systems.

All trim and electrical components in the locality of the repair must be removed or disconnected prior to panel
removal or replacement.
Welding and Gas Process Special Notes
Resistance spot welding, MIG welding and all gas processes may only be carried out on bare, unpainted or unplated

metal.
The flanges of panels, which are to be welded together, must be clean, corrosion free and treated as
appropriate with either weld-through or inter-weld sealer.
The resistance spot welding equ ipment used in vehicle repair does not always produce
a
weld of
equ
ivalent strength
to that produced in manufacturing. This means that a single row of spot welds should be spaced on a pitch of 19-
25 mm, which will usually result in more spot welds than found in the original factory joint.
Use a resistance spot weld cutter to remove resistance spot welds. Where a new joint is to be MIC welded, cut the
old resistance spot welds from the panel that is to be retained; the resulting holes are then used for plug welding.
Suitable holes may be drilled or punched as follows:
• 8.0 mm for sections up to 1.5 mm thickness
• 10.0 mm for thicker sections.
Always refer to the welding equipment manufacturers diagrams and tables for the relevant procedure.
May 1996 7-3

Air Conditioning
Working Practices O" 15-^?
Working Practices
General
Be aware of, and comply
with,
all health and safety
requirements.
Before beginning any repair or service procedure,
disconnect the vehicle battery ground connection
and protect the vehicle from dirt or damage.
Work in a well ventilated, clean and tidy area.
Recovery and chargeequipment must comply
with,

or exceed the standard detailed in the General
Description.
Handling Refrigerant
Wear eye protection at all times.
Use gloves, keep skin that may come into contact
with refrigerant covered. If the refrigerant comes
into contactwith youreyesorskin wash the affected
area immediatelyw'ith cool water and seek medical
advice, do not attempt to treat yourself.
Avoid inhaling refrigerant vapour, it wil
your respiratory system.
irritate
Never use high pressure compressed air to flush out
a system. Under certain circumstances a
combination of HFC 134A and compressed air in
the presenceofa source ofcombustion (for instance,
welding or brazing equipment), results in an
explosion that releases toxic compounds into the
atmosphere.
The refrigerant and CFC 12 must never come into
contact with each other
as
they form an inseparable
mixture that can only be disposed of by incineration.
Do not vent refrigerant directly into the atmosphere,
always use approved recovery equipment.
Refrigerant is costly but it can be recycled. Clean
the refrigerant, using the recovery equipment and
reuse it.
Carry out LeakTestsonly with an electronic analyser
dedicated to Refrigerant El 34A.
Do not attemptto guess the amount of refrigerant in
a system, always recover it and recharge with the
correct charge weight. Do not depress the charge or
discharge port valves to check for the presence of
refrigerant.
Handling Lubricating Oil
Avoid breathinglubricantmist,itwillcauseirritation
to your respiratory system.
Always decant fresh oil from a sealed container. Do
not leave oil exposed to the atmosphere for any
reason other than to fill or empty a system; PAG oil
is hygroscopic (it absorbs water) and iscontaminated
rapidly by atmospheric moisture.
Following the recovery cycle do not reuse the oil
when it has been separated from the refrigerant;
dispose of the oil safely.
System Maintenance
Do not leave the system open to the atmosphere. If
a unit or part of the system is left open for more than
five minutes, it is advisable to renew the receiver-
dryer. There is not a safe period in which work is to
be carried out. Always plug pipes and units
immediately after disconnection and only remove
plugs when re-connecting.
If replacement parts are supplied without transit
plugs and seals do not use the parts. Return them to
your supplier.
Diagnostic equipment for pressure, mass and
volumeshouidbecalibrated regularly and certified
by a third party organisation.
Use extreme care when handling and securing
aluminium fittings, always use a backing spanner
and take special care when handlingtheevaporator.
Use only the correct or recommended tools for the
job and apply the manufacturer's torque
specifications.
Keep the working area, all components and tools

clean.

8-8 May 1996

Air Conditioning
Lower Feedback Potentiomenter "3^^?
Blower Motors Potentiometers
The air conditioning system has two blower motors

(Fig.
1
-7) that operate together to maintain the flow
of air into the car at the desired
level.
The motors are
supplied from an ignition switched supply through
transistorised control circuits fitted in the motor
outlets. The circuits steplessly vary the speed of the
motors at
1
and 2 selections of the mode switch and
operate the motors to high speed when 3
is
selected.
The electronic components are assembled on a
heat sink and include a power transistor (Fig.
1
-9)
and feedback diode (Fig. 1-8). The switches are
supplied and controlled by the ECM.
When the mode switch is set to 3, the high speed
relay (Fig. 1-10) is energised from pin 16 of the

ECM,
opening
a
path to earth-ground, and allowing
full battery voltage to be applied to the motor. At 1
and 2, the motor is supplied with a continuously
variable voltage by the power transistor and the
earth-ground return is made via the ECM. The
feedback diode enables the ECM to sense the
voltage at the negative terminal of the blower
motor.
Lower Feedback Potentiometer
The lower feedback potentiometer determines the
position of the lower blend flap in the air
conditioning unit and feeds this information to the

ECM.
The ECM is thereby able to command the
lower flap servo motor to move the flap to a new
position and maintain the temperature of the air to
the feet and rear outlets at the desired level.
V 1
• 2
V3
Figure 1.
Key to Fig. 1

1.
Output signal from Pin 16 ECM

2.
Power feed
3. Blower feedback
Left hand Pin 22, Right hand 33

4.
Blower output Left Pin 31, Right 32
5. Control switch earth-ground
6. ECM earth-ground Pin 45
7. Blower motor
8. Feedback diode
9. Power transistor

10.
High speed relay
Figure 1.

1.

2.

3.
+5 volts from ECM Pin 43
Feedback signal to ECM Pin 29
Earth-Ground
The potentiometer is supplied with +5V from pin
43 of the ECM and returns its feedback signal via
pin 29. The feedback signal is 10OmV (COLD AIR)
to 1.2 V (HOT A!
R).
The potentiometer also provides
a single feedback signal of 2.9V when the blend
flap is in DEFROST. In this position, the feet and
rear outlets are closed and all air is directed to the

screen.

8-26 May 1996