MULTIPLEXING
Fault finding - Fault finding chart
88B
88B- 11
Fault finding - Fault finding chart
CAN network communications failure
No communication on the K lineCHART 1
No communication with computers
NOTESVehicle computer power supply for diagnostics:
Vehicle card in card reader.
Press and hold (over 5 seconds) the start button in the absence of start conditions (for
example: selecting a gear).
Connect the diagnostic tool and perform the required operations.
WARNING: The dipped headlights must be switched on to power the Xenon
headlights.
Try the diagnostic tool on another vehicle.
Make sure the tool version is more recent than CD-ROM No. 32.
Check:
–The connection between the diagnostic tool and socket (connection and cable in good condition).
–The computers' power supply.
–The engine compartment and passenger compartment fuses.
Make sure the CLIP sensor is properly fed by tracks 16 (+ 12 V), and 4 and 5 (earth) of the diagnostic socket,
indicated by the two red diodes on the sensor lighting up.
Make sure that the CLIP sensor is properly connected to the computer's USB port.
Make sure that the CLIP sensor is communicating properly with the vehicle's computers; this is indicated by
the two green diodes on the sensor lighting up.
green diodes red diodes
CAN Vehicle power supply
ISO Sensor power supply
Use the diagnostic socket to check the following tracks:
track 1 + After ignition
track 16 + Battery
tracks 4 and 5 Earth
Repair if necessary.
Check line continuity and insulation:
CAN H (diagnostic socket track 6)
CAN L (diagnostic socket track 14)
With a multimeter, make sure that the voltages at the diagnostic socket terminals are:
–2.5 V between CAN H (track 6) and the earth (tracks 4 and 5)
–2.5 V between CAN L (track 14) and earth (tracks 4 and 5) (average values)
See the Help with finding short circuits on the network heading in this section for how to detect short
circuits in the vehicle's multiplex network.
Check the continuity, insulation and for absence of interference on the K line of the diagnostic socket
(track 7).
