1997 ASTON MARTIN DB7 radiator

Electrics
Component Index Sheet 3 - 97
MY

Component
Name
Interior Light - Rear RH
Key Solenoid
Key-In Warning Switch
Low Coolant Signal Transmitter
Low Level Sensor (Screenwash)
Map Reading Light
Mass Airflow (MAF) Sensor
Multifunction Module
Number Plate Lamp - LH
Number Plate Lamp - RH
Oil Pressure Transducer (EOP)
PATS Module
PATS Transceiver
Performance Mode Switch
Powertrain Control Module (PCM)
Purge Cannister Vent Valve
Radiator Switch
Radio
Radio Aerial
Radio Telephone Connector
Radio Tweeter (LH)
Radio Tweeter (RH)
Rear Lamp - LH
Rear Lamp - RH
Relay - Air Conditioning
Relay - Air Conditioning W.O.T.
Relay - Air Pump
Relay - Auxiliary Load (
Relay - Auxiliary Load (
Relay - Courtesy Lights (
Relay - Clutch (
Relay-Day Time Running (
Relay - Drivers Seat Heater (
Relay - Fan Change-Over (
Relay - Fan Run On
Relay - Front Fog Lamps
Relay - Fuel Pump 1
Relay - Fuel Pump 2
Relay - Gearbox Failure Warning
Relay - Glass Drop
Relay - Hazard Unit
Relay - Headlamp Dipped Beam
Relay- Headlamps
Relay - Heated Front Screen Control
Relay - Heated Rear Window
Relay - Hood Down (Roof Down)
Relay - Hood Up (Roof Up)
Relay - Horn
Relay - indicator Unit (Flasher Unit)
Relay - Left Quarter Light Up
Relay - Left Quarter Light Down
Relay - Load
Relay- Main
Relay - Main Beam
Relay - Passenger Seat Heater
Component
Location
14-6
14-4
14-4
7-13
14-3
10-9
14-1
6-1
14-8
14-7
15-3
4-9
15-4
6-8
4-1
15-7
15-2
5-1
5-4
8-3
5-2
5-2
15-8
15-6
see relay location chart) di II II II
II II II II
II II II II
11 II II II
II II II II
II II II II
II II II II
II II II II
II II II II
11 II II II
II II II II
II II II II
II II It II
II II II II
11 II II II
II II II II
II II II II
II II II II
II II II II
II It II II
II II II II
11 II II II
II II II II
11 II II II
11 II II II
II II II II
II II II II
II II II II
II II II II
II II II II
Circuit
Reference
16-A2
9-D3
9-D3
12-82
3-A2
8-A4
5-D2
12-B5
16-D6
16-C6
5-C4
12-B1
9-C2
4-A2
6-B5
15-B3
5-D1
10-B3
16-C2
16-B5
8-A3
12-C2
15-B6
16-D2
3-A4
3-A5
1-A5
9-D1
12-D1
9-D1
1-B5
1-A6
23-D3
3-C4
3-A3
) 1-B5
) 17-A2
) 17-A4
9-D2
) 12-C1
) 8-C3
2-A2
) 2-B2
) 12-D3
) 8-C4
) 19-A2
) 19-A3
) 1-85
) 8-C3
) 18-A5
) 18-A5
) 12-D1
) 12-D2
) 2-83
) 24-D3
September 1996 6-45

'^T?
Air Conditioning
Compressors
Compressors
Compressor Clutch Control
The compressor
pu I
ley
is
driven continuously when
the engine is running. An electromagnetic clutch
allows the compressortobeengagedordisengaged.
The clutch is energised by battery supply voltage
when the clutch relay RF3 is closed by a signal from
the ECM (pin 21) via the engine management

system.

6^
o>o 1
4
Figure 1
Figure 2
Key to Fig. 2

1.

2.

3.

4.

5.
Condenser
Clutch relay supply
Compressor clutch
HSLP switch
Protection diode
Earth-ground
Key to Fig. 1

1.
+ve battery supply

2.
Clutch relay
3. Compressor clutch

4.
Pin 20 ECM supply to clutch relay solenoid
5. Earth-Ground
6. Earth-Ground
Trinary Switch
High Side Low Pressure Switch
The high side low pressure switch (HSLP) is
connected in the earth-ground return lead of the
compressor clutch
coil.
The switch is a function of
the trinary switch and monitors the pressure on the
high side of the refrigeration system. If the pressure
drops below 25 psi (+ 5 psi) the contacts open to de-
energise the clutch coil and disengage the clutch.
Low pressure occurs when there is a fault in the

system,
and the HSLP switch contacts remain open
until the fault has been rectified.
The condenser (Fig, 3) consists of a refrigerant coil
mounted in a series of thin cooling fins to provide
maximum heat transfer in the minimum amount of

space.
It is mounted directly behind the car radiator
and receives the fu
11
flow of ram air induced by the
forward motion of the car and the suction of the
cool ing
fan.
Refrigerant enters the inlet at the top of
the condenser as a high pressure hot vapour. As the
vapour passes down through the condenser coils
cooled by ram air, a large quantity of heat is
transferred to the outside air and the refrigerant
changes to a high pressure warm liquid.
May 1996 8-35

^2?
Air Conditioning
System Checking with the Manifold Gauge Set
Compressor Malfunction
Complaint.
Cooling is not adequate.
Condenser Malfunction or System Overcharge
Complaint.
Little or no cooling. Overheating of the engine may
also be noted.
BLUE LOW SIDE

BLUE
LOW SIDE BED HICH SIDE
Condition

1.
The low side gauge reading is too
high.

2.
The high gauge reading is too low.
3. The sight glass is free of bubbles and the system is
fully charged.

4.
The discharge air from the evaporator is not
sufficiently
cool.

Diagnosis.
Internal leak in the compressor.
Correction.

1.
Depressurise the system.

2.
Renew the compressor and the drier bottle.
3. Evacuate the system using a vacuum pump.

4.
Charge the system with new refrigerant.
5. Operate the system and check the performance.
HIGH
Condition.

1.
The low side gauge reading excessively
high.

2.
The high side gauge reading is also excessively

high.

3. Bubbles may appear occasionally in the sight glass
and the liquid line to the evaporator is very hot.

4.
The discharge air from the evaporator is warm.
Diagnosis.
The condenser not operating correctly through lack
of cooling caused by too high a high side pressure.
The system may have either
a
normal or overcharge
of refrigerant.
Correction.

1.
Checkthecompressordrivebeltforcorrecttension.

2.
Check the condenser for clogged air passages
preventing air flow through the condenser.
3. Inspect the condenser mounting for correct radiator
clearance.

4.
Check for correct fan operation.
5. Check the coolant pressure capfor correct type and

operation.

May 1996 8-43

^^?
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