Network, generic (extended)

U3522 High Voltage System Interlock Circuit F Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3522 is set when loop F behaves inconsistently, for instance when redundant evaluation channels reach different verdicts or the signal timing is off. Such checks exist because the interlock belongs to a safety function: Samsung SDI notes that it then needs an ASIL rating and failure-rate figures for its parts, so hidden faults in the monitoring path have to be caught, not just an open loop. CARB counts the interlock among safety-only systems, which is why this code concerns electrical safety rather than emissions and why lamp behaviour differs between makers. No manufacturer publishes U3522. Expect sporadic refusals to become ready.

Likely causes

Redundant measuring channels for loop F disagree because of a sensing fault
Intermittent contact in a loop F connector
Internal fault of the evaluating controller

Symptoms

  • Ready mode occasionally refused, then available again
  • High-voltage warning that comes and goes

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,000
Time1–6 h

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

Parts involved

hvil loop f

Related codes

U3521U3523U3524U351EP0A0B

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