U3546High Voltage System Interlock Circuit P Performance
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3546 marks loop P as implausible. On large vehicles the mechanical routing of HV cables affects the interlock too. Gillig's field service campaign FSC 22-13-2479 for its Gen 2.0 and 2.5 battery electric buses found that HV battery cables in one equipment compartment lacked adequate support brackets; the outcome was an intermittent HVIL fault 8175, sometimes with the HV exposure lamp lit, and the fix was added bracketry. A heavy cable that swings with every bump can tug at its plug just enough to upset the loop for an instant. No maker documents U3546. Look for unsupported cable runs close to the plugs of loop P.
- What you may notice
- Interlock fault that comes and goes, more often on rough roads
- High-voltage warning lamp lighting briefly
- Brief loss of high-voltage power
- Likely causes
- LikelyHV cable without adequate brackets pulling on a loop P plug
- PossibleLoose contact in a loop P connector
- RareCable clamp or bracket not refitted after repair
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.