U3525High Voltage System Interlock Circuit G
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3525 stands for a fault on the seventh interlock loop, circuit G, that the module does not classify further. Auxiliary high-voltage consumers are candidates for loops of their own: Sanden runs an interlock loop beside the HV plug between an electric A/C compressor and the traction battery, and a Chinese design cited by Caterpillar links an air-conditioning interlock circuit to the main one over CAN. On Mercedes model line 243 the PTC heater's control unit logs its own interlock code, P154700. Which consumer sits on loop G is not public. A dead loop G may only disable heating or cooling, or may block the whole system.
- What you may notice
- Air conditioning or electric heater unavailable
- In some designs no ready mode at all
- High-voltage or climate warning in the cluster
- Likely causes
- LikelyHV plug of an auxiliary consumer such as compressor or heater not latched
- PossibleLoop G wiring to the auxiliary consumer damaged
- RareInterlock contacts inside the consumer's connector damaged
- RareEvaluating controller faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.