1997 ASTON MARTIN DB7 cooling

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The Aston Martin Lagonda Diagnostic System
I nstal lation I nstructions
Bench Mounting
The base station may also be mounted on a bench, which
must be in a safe position, stable and protected form
hazards and impacts. The base station must be mounted
at the back of the bench. 'Z' clips are provided for
permanent mounting. The bench surface must be kept free
from dust at all times.

CAUTION:
A gap under the base station must be
maintained free from obstructions to allow a flow of air
under the unit for cooling.
Electronic Module installation
WARNING: The base station electronic module must be
disconnected from the mains supply prior to installation/
removal from the base station assembly. DO NOT
reconnect to the mains supply until the module is safely
fitted into the base station. This unit must be earthed.

Note:
Users in North America are advised to replace the
ceramic mains fuse in the electronic module with theglass
fuse supplied.
Procedure

1.
Unlock the base station door

2.
Pull the right spring-loaded hinge (Fig 4-1) and
remove the door.
3. Removetheelectronicsmodulefrom the packaging
and place it on a firm surface.

4.
Remove the two screws and washers from the front
of the module (Fig 4-3).
5. Insert the mains power lead into the socket at the
rear of the module Fig 4-4), DO NOT CONNECT
TO THE MAINS SUPPLY.
6. Insert the two guide pins on the sides of the module
(Fig 4-5) into the base station slots.
7. Slide the module into the base station until fully

home,
raise the front so that it is level and draw it
slightly forward.
8. The two connectors on the front of the module will
appear through the matching holes in the base

station.
Support the module whilst refitting the two
retaining screws and washers (Fig 4-6).
9. Secure the mains lead to the underside of the base
station using the two cable ties provided (Fig 4-7).

10.
If bench mounting, the base station will need to be
turned on its back to install and secure the mains

lead.

11.
Refit the base station door.
CAUTION: Take care to avoid the sharp edges of the
module whilst installing. Take care to support the
module from the underside until the mounting
screws are secured.
Figure 4. Electronic Module Installation
May 1996 9-9

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The Aston Martin Lagonda Diagnostic System
Users Guide
Output State Control - 97 MY
This menu item provides a quick test of the basic electro­
mechanical components controlled by the PCM. These
tests should be performed in a key on engine off state.
The selections available are:
• Low Speed Cooling Fans
• High Speed Cooling Fans
• Set Electromechanical Outputs
Low and High Speed Fans
Selecting and confirming either the low or high speed
cooling fans will run the fans at the selected speed for 5
seconds to verify their operation.
Electromechanical Outputs
This selection will cause the following electromechanical
devices to operate for five seconds
Air Pump
Fuel Pumps
Canister Purge Valve
Idle Air Control Valve
Observing each device in turn as the PCM outputs are
turned 'On' will enable the technician to verify correct

operation.

September 1996 9-35

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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

The Aston Martin Lagonda Diagnostic System
Users Guide
•=2?

Clear all Trouble Codes
Selecting the clear all trouble codes icon will invoke a
confirmation window.
EEC-V EMS
dri
dri
CONFIRM
Clear all logged trouble
codes?
O

'Clear
All Codes' confirmation
screen

Selectingthe'tick'will instructthePDU to clear all logged
trouble codes in the selected module
and
return to the no
logged codes screen.
Select the 'tick' icon to exit Diagnostic Trouble Codes.
Clear Selected Trouble Codes
(95 MY Zytek Engine Management Only))
If
you
wish only to clear selected codes on the Zytek ECU
and
leave others
for later
investigation,
proceed
as
follows:
Highlight only the trouble code(s) to be cleared.
ZYTEK EMS
1 : Idle speed control valve driver #1
5 : Purge Valve driver #1
12 : Cooling fan#l relay driver
14 : Lannda heater
#2
driver
1 : Idle speed control valve driver #1
Highlighting
Selected
Trouble
Codes

Select the 'clear selected trouble codes'
icon;
this will
invoke a confirmation window.
Selectingthe 'tick' icon will instruct
the
PDU to clear only
the selected trouble codes from the control module fault

table,
and if successful, the system will return to the
'Diagnostic trouble codes' screen.
If any attempt to clear trouble codes is unsuccessful, a
warning window will be displayed.
This will indicatethat
some selected
trouble codes remain
logged,selectingthe'tick'iconwillreturntothe'Diagnostic
trouble codes' screen.
Select the 'tick' icon again to exit Diagnostic Trouble
Codes.
9-54 September 1996