Computers/Controls - CAN Communication Diagnostic Information
Date: August 22, 2013
CAN COMMUNICATION - NETWORK DIAGNOSTIC FLOW CHART
Bulletin amended to change End Diagnosis 5 to 4 and End Diagnosis 6 to 5. No other changes have been made to the body of this bulletin. Discard previous versions.
APPLIED VEHICLES: All 2005 - 2013MY Nissan Vehicles
This TSB is for troubleshooting of CAN Modules with "Diag-On-CAN" Diagnostics. The flow charts below are meant to troubleshoot current CAN DTCs. The flow charts are intended to diagnose one module at a time; repeat the process as needed for additional control units.
Definition of CAN Codes:
U1000 - missing ECM CAN communications not related to OBD2 system
U1000 - missing CAN communications for all other ECUs
U1001 - missing ECM CAN communications related to OBD2 system
U1002 - similar to U1000, but has a tighter timing spec to set the DTC
U1010 - Module has internal Issues
Always diagnose CAN communication codes first, U1000, U1001, U1002, U1010, then network codes, UXXXX, and then all other codes.
A quick method to test CAN communications is to operate the vehicles functions such as Hazards, Brakes, Tachometer, PRNDL, Speedometer, 4WD, Difflock, Seat Memory, Power Back Door or High Beams.
In a low voltage situation (less than 10V), modules will stop communicating at different voltages.
Integrated Power Distribution Module (IPDM) is a smart relay and fuse box. It powers other modules in the same way fuses and relays do.
CAN voltages can be checked via CONSULT.
Missing "Ignition 2" fuse or other high level fuses can cause CAN Diag Support Monitor to not work.
High level fuses such as "Ignition 1", "Ignition 2" and "Elec B" power many modules.
Pins/terminals can be bent and still pass visual inspection.
When troubleshooting a harness that has multiple inline connections, section off the harness and isolate it one portion at a time. Add a terminating resistor to the end of the harness in substitution of the terminating modules.
If a module has multiple connectors, disconnect one at a time.
120 ohm resistors may be needed to perform diagnostics.
Normal CAN Measurements
Main Types of Issues
Use legend below for flow charts and Table A.