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U3526 High Voltage System Interlock Circuit G Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3526 reports an implausible result for loop G. Not every interlock is a wire loop: Rivian patented a virtual interlock in which a controller first brings the DC bus up to a low, safe voltage only, gathers the voltages that the high-voltage components report over CAN, and raises the bus to operating voltage only if those reports are acceptable. With such a scheme a performance fault means values that contradict each other rather than a broken wire, for example one component seeing a bus voltage far from the battery's. No maker documents U3526. Missing or stale CAN data, a faulty voltage sensor or a loose HV plug are the main suspects.

Likely causes

Voltage sensing inside one high-voltage component faulty
Voltage message missing or late on the CAN bus
HV plug not fully seated, so one component sees no bus voltage

Symptoms

  • Start-up of the high-voltage system aborted
  • Communication codes in other control units at the same time

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,000
Time1–5 h

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

Parts involved

hvil loop g

Related codes

U3525U3527U3528U3522P0A0B

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