80-JB566-1 Rev. G 20-1
MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION
20
J1939 Packet Detection Problem
Problem: J1939 Packet Detection Fails
Ignition must be on for the truck to broadcast/supply vehicle data.
Note: If the Core Data Items and J1587 tests pass (i.e. green check), it’s acceptable for the
J1939 Packet Detection test to fail. This would mean that the MCP50 system is getting its
vehicle data from the J1587 link. Many pre-2007 trucks do not submit J1939 packets.
This is determined by the VDS configuration sent to the unit from the Vehicle Data
Configuration (VDC) on the Customer Portal. Contractors and Service Centers should first
contact the customer to verify that the units were configured correctly.
In order to get J1939 data, a truck’s engine must be supplying the J1939 data, a connection
must be made to the J1939 wires (Power/IO cable). Many old trucks/engines do not transmit
J1939 packets.
If packets are not detected, check the connections to the J1939 data link and verify that it is
properly configured.
In 8xx code and higher, the MCP50 will auto detect J1939 bus traffic
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