How do I troubleshoot my J1939?
- Turn the ignition key off and disconnect the batteries. Set the multimeter to ohms and place the leads between CAN + (Pin C) and CAN – (Pin D).
- CAN + and CAN – will be tested separately. Turn the ignition key ON and put one test lead on ground and the other lead on CAN + (Pin C) or CAN – (Pin D).
What is fault code J1939?
The J1939 fault code error message consists of a Source Address (SA) identifying the Electronic Control Unit (ECU) sending the DTC (SA0 = Engine Controller #1), a Suspect Parameter Number (SPN) which identifies the parameter sending the fault code error message, and a Failure Mode Identifier (FMI) which identifies the …
How do you test a terminating resistor?
To check your network’s termination, disconnect the CAN interface’s D-sub 9 pin from the network and measure resistance through the cable by placing a digital multimeter / ohmmeter between pin 2 and 7. Make sure any CAN nodes e.g. a motor controller, are still attached but powered down.
CAN bus short to ground?
Shorts and opens: The CAN controllers will tolerate a short circuit of one of the two lines to ground because of the characteristics of the differential bus. It cannot tol- erate both CAN bus wires shorted to ground or to each other. It will tolerate one of the CAN lines being open or disconnected.
CAN High Low voltage?
Peak CAN High and Peak CAN Low voltages normally range between 1.7 and 3.3 Volts. Voltage measurements are averaged for each second.
How to check J1939 and diagnostic truck can networks?
TS 1033683 : Checking and Testing J1939 and Diagnostic “Truck” CAN Networks 3 Voltage readings between pins A & C should be 2.6V +/- 0.1V Voltage readings between pins A & D should be 2.3V +/- 0.1V Voltage Test Result Meaning • If there is no voltage – There is likely a short in the J1939/H1939 backbone or one of the modules itself.
When to check the J1939 on pins C and D?
When checking the J1939 on pins C and D make sure the ignition is off and no modules are communicating when you check the resistance. What I see all the time are inactive codes in the ABS for J1939 time outs on Freightliner Columbia.
When to check J1939 data link troubleshooting?
When you are checking the [&data&] [&link&], if the problem is not present, the [&data&] [&link&] will show [&good&]. 7.The J1939 [&data&] [&link&] may be referred to as data bus, or CAN as well. 8.A module is capable of being connected to the public and private [&data&] [&link&], but the information remains separate.
Can you check data link on Freightliner M2?
Freightliner M2 and C2 chassis you must disconnect the batteries to check the J1939. These trucks and/or school busses have bulk head and chassis module that communicate all the time even with the ignition off and the data link can’t be checked as long as module are transferring data on the J1939.