Network, generic (extended)

U3515 High Voltage System Interlock Circuit C

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Connector or cover belonging to loop C opened during work and not refitted correctly
Interlock harness of loop C damaged
Fault in a coupled loop opening loop C as well
Monitoring module unable to drive or read loop C

Symptoms

  • No ready mode, HV system switched off
  • Interlock codes for more than one loop stored together
  • Charging blocked

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,500
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hvil loop chv connectors

Related codes

U3516U3517U3518U3511P0A0A

References: patents.google.com, patents.google.com, patents.google.com, law.cornell.edu.