Grand Cherokee 2WD V8-5.7L VIN 2 (2005)
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IOD fuse installed
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FCM is configured correctly
SET CONDITION
Bus messages not received for approximately 2 to 5 seconds.
POSSIBLE CAUSES
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CAN B BUS circuits open or shorted
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DTCs related to battery voltage, ignition, or VIN messages
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FCM not configured correctly
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Power or ground from the reporting module
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Module that set this DTC
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Previous service performed within the last 100 key cycles (fuse/relays removed, wiring service, battery disconnect)
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Low battery/jump start condition
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IOD fuse was removed during shipping
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Check for related TSBs
DIAGNOSTIC TEST
1. VERIFY DTC IS STORED
NOTE:
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Stored faults may indicate a customer perceived intermittent condition.
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Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.
With the scan tool, read stored DTCs.
Q: Is this DTC stored?
YES: Go To 2
NO: Diagnose the active DTC. Refer to the Index for a list of the symptoms.
2. CHECK THE ENVIRONMENTAL DATA
With the scan tool, read the loss of communication environmental data.
Q: Does the loss of communication environmental odometer data match up to any of the previous service procedures listed in the possible
causes or are their any stored CAN B or C hardware electrical, battery, ignition voltage, VIN missing/mismatch, FCM configuration
DTCs present with matching environmental data?
YES: These DTCs may have been the result of other service procedures performed. Clear DTCs.
NO: Go To 3
3. VERIFY INTERMITTENT LOST COMMUNICATION DTC - WIRING CONCERNS
Turn the ignition on.
With the scan tool, select Network Diagnostics.
Q: Is there more than one ECU with stored DTCs "Logged Against" the module and one or more lost communication DTCs stored in the
offending module?
YES: Verify if the vehicle was recently in for this type of service. Otherwise, visually inspect the related wiring harness for chafed, pierced,
pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals. Repair as necessary.
NO: Go To 4
4. VERIFY INTERMITTENT LOST COMMUNICATION DTC - OFFENDING MODULE
Turn the ignition on.
With the scan tool, select Network Diagnostics.
Q: Is there more than one ECU with stored DTCs "Logged Against" the module and NO lost communication DTCs stored in the
offending module?
YES: Check for TSB related to this offending module.
NO: Go To 5
5. VERIFY INTERMITTENT LOST COMMUNICATION DTC - REPORTING MODULE
Turn the ignition on.
With the scan tool, select Network Diagnostics.
