Kenworth T680 SPN 520202 FMI 14 Load Disconnect Switch Error

Question

My 2019 T680 is throwing a SPN 520202 FMI 14 code on the dash and the VICU is complaining about a switch state mismatch. The truck starts fine, but I am getting intermittent warnings about the load disconnect switch being in the wrong position while driving. It seems to happen more often when we hit rough patches of road or vibration starts up.

Lina Brooks · Accepted Answer

The issue was a corroded connector at the load disconnect switch harness junction under the cab. I found green crusties on pins 2 and 4 of the 6-pin connector. I ended up bypassing the connector with a sealed butt-splice kit and replaced the switch itself (Part # P27-1111-110) just to be safe. Total repair cost was about $85 for the part plus two hours of labor tracking down the voltage drop. The mismatch code cleared immediately once the VICU saw the steady 12v signal on both circuits.

Mike Reynolds · Answer

Check the wiring harness where it passes through the floor near the seat. Those Paccar cabs have a tendency to rub the harness raw if the grommet isn't seated perfectly.

Pete Sanders · Answer

You need to pull the DAVIE4 software and look at the real-time data for the switch states. One side of the switch sends a signal to the CECU and the other to the VICU, if they don't agree for more than a few seconds, it triggers that FMI 14.

road_rambler · Answer

Check the ground strap on the load disconnect solenoid itself. If the solenoid is failing internally, it can create enough resistance to drop the voltage signal back to the controller, making it think the switch is open when it's closed.

Kenworth T680 SPN 520202 FMI 14 Load Disconnect Switch Error

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