U3513High Voltage System Interlock Circuit B Low
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3513 reports a signal on interlock loop B that stays below its lower limit while the loop is energised by the module. What that means depends on the circuit: where the module feeds a test voltage in and reads it back at the far end, an opened plug reads low just like a wire touching ground. GM's documented loop A gives a sense of scale: its low code sets when less than 30 % of its 5 V check voltage comes back in two 12.5 ms samples, Type A. Texas Instruments' reference design shows how a current-fed loop can tell both apart: a grounded wire makes the loop current vanish while the supply current rises, with an open loop both drop. No maker publishes U3513. The contactors stay open; check loop B for chafed wires and unplugged connectors.
- What you may notice
- No ready mode, HV contactors stay open
- Hybrid or EV warning lamp, MIL depending on maker
- Charging not possible
- Likely causes
- LikelyInterlock wire of loop B chafed through to ground
- PossiblePlug or cover in loop B open, read as low by the sensing circuit
- PossiblePushed-back interlock terminal without contact
- RareInterlock source in the monitoring module not delivering its signal
- 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.