U3527High Voltage System Interlock Circuit G Low
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3527 sets when the level on loop G drops below what the module expects. When several controllers watch interlock lines, the reporting unit already narrows the search. A Mercedes service bulletin on the 243 model series shows this with loop A codes: the DC charging unit and the AC charger each store a ground-short code, the battery management a short to positive, and the PTC heater has a separate code. For loop G, start measuring at the controller storing U3527, follow its section outward and compare the codes in the other units. No maker publishes U3527. While the low reading persists, the contactors behind loop G stay locked.
- What you may notice
- Vehicle does not become ready, or charging is refused
- Interlock codes in more than one control unit
- Likely causes
- LikelyLoop G wire cut or chafed to ground near a control unit
- PossiblePlug in the section of the reporting unit not connected
- RareLoop source of the reporting controller failed
- 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.