U3547High Voltage System Interlock Circuit P Low
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3547 reports a low value on loop P, and the contactors drop out with it. A design flaw can be the cause too. Kenworth (campaign 25KWC) and Peterbilt (25PBC) recalled battery electric T680E, 520EV and 579EV trucks under NHTSA number 25V181: with certain HVIL circuit layouts in their Accelera power control accessory subsystem, high voltage could be lost and the contactors open without warning, cutting propulsion. The remedy pairs a software check with two overlay harnesses. If a commercial vehicle keeps losing power on loop P, ask for open campaigns before hunting for wiring faults. No maker documents U3547.
- What you may notice
- Sudden loss of propulsion while driving
- Contactors open without prior warning
- No restart until the loop reads normal
- Likely causes
- PossibleInterlock circuit layout covered by a recall, overlay harness not yet fitted
- PossiblePlug in loop P open or interlock pin pushed back
- PossibleLoop P wire shorted to ground
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.