MOTO GUZZI 2Q000297 Service Station Manual page 152

Electrical system
several sensors present on the motorbike has been obviated. The sensor signals are shared by the two
electronic elaboration units (instrument panel and control unit).
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Cable number reduction: The CAN line travels through a twisted cable to several nodes.
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These nodes can also isolate the errors without causing a system breakdown (FaultsCon-
fination).
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Immunity to interference: the signal travels through two cables and the signal reading is
differential (voltage difference between the two signals on both cables). If the two signals
are disturbed by an external factor, their difference remains unaltered.
•
Communication speed: messages travel at a speed of 250 kbps (data arrive at nodes every
20 ms, i.e. 50 times/second).
CAN PROTOCOL (CONT. NETWORK AREA)
The communication protocol is CSMA/CD (Carrier Sense Multiple Access w/ Collision Detection).
In order to transmit, every nod must first check that the BUS (the connection among all devices) is free
before attempting to send a message with BUS (Carrier Sense).
If during this period there is no activity on BUS, every nod has the same chance to send a message
(Multiple Access). If two nodes start transmitting simultaneously, the nodes recognise the "colli-
sion" (Collision Detection) and initiate an exchange action based on message priority (messages remain
unaltered during exchange and there is no delay for high priority messages).
CAN protocol is based on messages and not on addresses. The message itself is divided into several
parts (frames), each of which has a meaning: message priority, data contained, error detection, recep-
tion confirmation, etc.
Every network nod receives all the messages sent through the BUS (with reception confirmation or error
messages) and each nod decides if the message is to be processed or rejected. Besides, every nod
can request information from the other nodes (RTR = Remote Transmit Request).
Level in electrical circuit diagram
CAN Line
Pin-out
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Between PIN 26 and 27 of the engine control unit
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Between PIN 1 and 8 of the instrument panel
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Between PIN 5 and 6 of the ABS control unit
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Between PIN 3 and 4 of the left light switch
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Between PIN 1 and 2 of the bluedash preparation
Diagnostic tool - Electrical errors
CAN line U0001 NO SIGNAL (BUS OFF) - Bus Off.
Error cause
•
No communication on CAN line (PIN 26 and/or PIN 27): problem on the whole network (for
example, battery cut-off or short circuited or shorted to ground).
Troubleshooting
ELE SYS - 152
V7 III ABS