Dodge Caliber. Manual - part 476
U0020-CAN B BUS OFF PERFORMANCE
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
Continuously
•
Set Condition:
Whenever the CAN B Bus (+) or CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.
Possible Causes
ACTIVE U0020 CAN B BUS DTC IN OCCUPANT CLASSIFICATION MODULE
(D55) CAN B BUS (+) CIRCUIT OPEN
(D54) CAN B BUS (-) CIRCUIT OPEN
OCCUPANT CLASSIFICATION MODULE (OCM)
Diagnostic Test
1.
VERIFY DTC U0020–CAN B BUS IS ACTIVE
Turn the ignition on.
With the scan tool, read Occupant Classification Module (OCM) DTCs.
Does the scan tool display active: U0019-CAN B BUS?
Yes
>> Go To 2
No
>> If the DTC is stored, check for an intermittent condition by inspecting the related wiring harness for
chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken,
bent, pushed out, spread, corroded, or contaminated terminals.
Perform *AIRBAG SYSTEM VERIFICATION TEST - VER 1.
2.
CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE FRONT CONTROL MODULE (FCM)
With the scan tool, read Front Control Module (FCM) DTCs
Does the scan tool display any active CAN B BUS related DTCs?
Yes
>> Diagnose and repair the DTC(s). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES -
DIAGNOSIS AND TESTING).
No
>> Go To 3
3.
CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN
Turn the ignition off.
Disconnect the negative battery cable.
Disconnect the OCM connectors.
Disconnect the Front Control Module (FCM) C1 connector.
Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module C1 connector and the
OCM C1 connector.
Is the resistance below 2.0 ohms?
Yes
>> Go To 4
No
>> Repair the (D55) CAN B Bus (+) circuit for an open.
Perform *OCCUPANT CLASSIFICATION MODULE SYSTEM VERIFICATION TEST.
PM
RESTRAINTS - ELECTRICAL DIAGNOSTICS
8O - 301