Network, generic (extended)

U3532 High Voltage System Interlock Circuit K Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3532 indicates that loop K does not respond the way the controller expects. Some checks run only while the system powers up. A Ford patent describes one: during precharge a switch holds the high-voltage bus between an upper and a lower level far below operating voltage, and the interlock test takes place inside that window. Too little current then suggests a connector that is not seated, too much a short, and only a passed test lets precharge carry on. A start-only test of this kind can let a marginal contact pass on one key cycle and fail on the next, so the code may come and go between trips. No maker publishes U3532. Expect occasional refusals to become ready.

Likely causes

Marginal contact in a loop K connector that passes some start checks and fails others
Fault in the precharge path disturbing the start-up check
Controller software with outdated check limits

Symptoms

  • Vehicle sometimes does not become ready at switch-on, then works on the next attempt
  • Fault stored at start-up rather than while driving

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

hvil loop k

Related codes

U3531U3533U3534U352EP0A0B

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