Network, generic (extended)

U353D High Voltage System Interlock Circuit N

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U353D is the general code for interlock circuit N, the thirteenth loop in J2012 lettering; designs with that many loops are only conceivable on very large high-voltage systems. No maker documents U353D publicly. Moisture is a frequent root cause on interlocks of any letter: FCA bulletin 08-131-21 for the 2021 Jeep Wrangler plug-in hybrid traces a no-start with P0A0A to water getting past a pinched orange seal into the P1 and P2 HV connectors under the car, often logged together with an isolation fault (P0AA6). Where corrosion has set in, the harness or the power inverter module has to be replaced. Inspect seals before cleaning pins.

Likely causes

Water in a loop N connector because a seal is pinched or damaged
Connector in loop N not fully seated
Interlock pins corroded after earlier moisture
Controller that drives and reads loop N faulty

Symptoms

  • No ready mode or no start, often after rain, washing or wading
  • Isolation fault stored alongside the interlock code
  • Hybrid or high-voltage system warning in the cluster

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time1–5 h

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

Parts involved

hvil loop nhv connectors

Related codes

U353EU353FU3540U3539P0A0AP0AA6

References: static.nhtsa.gov, law.cornell.edu.