U3515High Voltage System Interlock Circuit C
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3515 is the general fault of a third interlock loop, circuit C. Such a loop exists where one or two are not enough: Caterpillar's patent for battery machines forms a separate interlock circuit from each battery group with its disconnect and contactor pair, and Samsung SDI mentions designs with more than two independent loops for parts inside the pack. Volvo couples two loops through an isolated relay so that a fault in one opens the other, which is why codes for several loops can be logged together. Which component a manufacturer wires into loop C is not documented publicly for any vehicle. U3515 applies when loop C fails without a more specific low, high or performance result; HV power remains off until the loop is closed again.
- What you may notice
- No ready mode, HV system switched off
- Interlock codes for more than one loop stored together
- Charging blocked
- Likely causes
- LikelyConnector or cover belonging to loop C opened during work and not refitted correctly
- PossibleInterlock harness of loop C damaged
- PossibleFault in a coupled loop opening loop C as well
- RareMonitoring module unable to drive or read loop C
- 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.