Can Bus Diagnostics - Lotus Evora Service Notes

Lotus Service Notes
WF.3 - DATA LINK CONNECTOR (DLC)
In order to provide for communication
with the SRS Sensing and Diagnostic Module
(SDM), the Lotus TechCentre may be plugged
into the special 16 terminal harness connec-
tor socket, known as a Data Link Connector,
located beneath the driver's side fascia at the
outboard side of the footwell. Communication
with engine management and anti-lock brakes
is also available via this connector.
WF.4 - TROUBLE CODES
All the time the ignition is switched on, the Sensing and Diagnostic Module (SDM) continuously monitors
the resistance of various parts of the SRS electrical circuit, and compares these values with pre-programmed
tolerance bands to enable it to recognise 'faults' in the system and light the airbag tell tale lamp in the instru-
ment cluster. If such a fault is detected, the SDM stores a 'Trouble Code' for that particular type of fault in its
memory.
i). Current (Present) Codes - Faults that are currently being detected. Current codes are stored in the SDM
Random Access Memory (RAM), which will be cleared if the vehicle battery is disconnected.
ii). History (Not present) Codes - All faults detected since the last time faults were cleared from the memory
using the Lotus TechCentre. History codes are stored in the SDM Electronically Erasable Programmable
Read Only Memory (EEPROM) and are not cleared if the battery is disconnected.
Vehicle crash data is also stored in coded form in the SDM and is not erasable. New SDMs are supplied
only against V.I.N. and on exchange with the old unit.
WF.5 - LOTUS TECHCENTRE

CAN BUS Diagnostics

Controller Area Network (CAN) is an electronic standard to allow high speed communication between modules
and controllers, via a serial data BUS. The BUS is a circuit linking the modules to the controller, consisting of
a pair of cables, twisted together to reduce electromagnetic interference, and carrying a square wave voltage
signal corresponding to '0's and '1's, coded in such a way as to identify and prioritise the individual messages.
On the Evora, CAN based systems include; engine management system, instrument pack, tyre pressure moni-
toring and ABS/Traction Control/ESP.
A CAN compliant on-board diagnostic system is accessible via a 'stand alone' lap top PC loaded with 'Lotus
TechCentre' software to allow the CAN based serial data to be read. A Vehicle Communication Device (VCD;
T000T1476F) is used to connect the vehicle's Data Link Connector (DLC) to the laptop Lotus Techcentre. En-
gine programming, live data display, diagnostics of engine, ABS and airbag systems, and service tell tale lamp
resetting are all carried out via the Lotus TechCentre.
The minimum specification of the laptop computer for installation of the Lotus Techcentre software is as
follows:
Processer 1.70 Ghz;
1 GB RAM;
40 GB HDD;
CDRW DVD ROM;
WIN XP PRO;
USB interface;
Ethernet or Wireless LAN
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Section WF