2018 Freightliner Cascadia - Intermittent U0075 and Dash Gage Sweep

Question

While driving on the highway, my dash suddenly does a full sweep and I get a 'No J1939 Data' message on the ICUC. The truck keeps running but I lose my gear indicator and cruise control immediately kicks off. It usually clears itself after a few minutes but it is happening more frequently now.

backyard_bart · Accepted Answer

Found the issue at the Star Point connector located underneath the dash near the steering column. There was significant corrosion on the shorting bar of the CAN C distribution block caused by a small windshield leak. Cleaned the pins with electrical contact cleaner, replaced the shorting bar (Part #A0005400115), and resealed the top of the windshield. Total parts cost was under $40 and it solved the communication dropouts permanently.

turbo_tony · Answer

Since your transmission data is dropping, inspect the TCM harness near the rear of the transmission. It's common for the harness to rub against the air lines and wear through the J1939 shield, causing intermittent communication shutdowns.

Ashley Park · Answer

Check the green and yellow twisted pair wiring behind the sleeper wall if you have an auxiliary HVAC unit. I have seen the insulation rub through on the cab floor reinforcement plate, which shorts the entire Bus C to ground and throws U0075.

wrenchqueen · Answer

You need to check the terminating resistors on the J1939-C bus. Measure the resistance between CAN High and CAN Low at the diagnostic port with the batteries disconnected; you should see exactly 60 ohms. If you see 120 ohms, one of your resistors is missing or the circuit is open.

2018 Freightliner Cascadia - Intermittent U0075 and Dash Gage Sweep

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