U352E

What it means

U352E is a generic code meaning a performance fault in High Voltage System Interlock Circuit J. The interlock (HVIL) is a low-voltage safety loop that runs through high-voltage connectors, covers and components to confirm the system is sealed before the high-voltage contactors close. The control unit has seen the loop signal outside its expected range, out of time or intermittent, but not necessarily a plain open or short. Which part of the vehicle 'circuit J' covers depends on the model, so use the manufacturer's wiring information.

Symptoms

• Hybrid or electric system warning light or message on the dashboard
• Vehicle will not go into ready mode or will not start
• Reduced power or limp mode
• Loss of drive while moving, or intermittent power cut-outs
• Charging will not start or stops early on a plug-in or electric vehicle
• Other high-voltage or network fault codes stored alongside

Possible causes

• Loose, corroded, damaged or poorly seated interlock connector or pins in the high-voltage looplikely
• High-voltage connector, service disconnect or cover not fully latched or refitted after earlier worklikely
• Damaged or chafed interlock wiring causing high resistance, intermittent open circuit or shortpossible
• Water ingress or contamination in a high-voltage component connectorpossible
• Faulty interlock switch or signal circuit inside a high-voltage component such as the battery, inverter, compressor, heater or chargerpossible
• Fault in the control unit that generates or monitors the interlock signal, or a software issue where the manufacturer has a known updaterare

How to diagnose

1. Read all stored and pending codes with freeze frame data, noting whether the fault is current or intermittent and what other high-voltage codes are present
2. Check for manufacturer bulletins and the wiring diagram to identify which components and connectors are in interlock circuit J for this model
3. Make sure only a technician trained in high-voltage systems carries out further work, and follow the manufacturer's shutdown and isolation procedure
4. Visually inspect the interlock loop connectors, covers and the service disconnect for correct seating, latches, damage, corrosion, moisture or signs of previous repair
5. Inspect the low-voltage interlock wiring for chafing, pinched sections or pushed-back pins, and wiggle-test the harness while watching live data
6. With the system isolated, test the loop for continuity, resistance and shorts to ground or voltage against the manufacturer's specification
7. Check each component in the loop for faults following the manufacturer's procedure
8. Clear the code, then road test or cycle the system and recheck for the code returning

How to fix

• Reseat, clean or replace damaged interlock connectors and terminals, making sure latches fully engage
• Refit the service disconnect or any high-voltage cover correctly and replace damaged seals
• Repair or replace damaged interlock wiring using approved methods
• Dry out and fix the source of water ingress, replacing contaminated connectors or components as needed
• Replace the faulty high-voltage component or its interlock circuit if testing shows the fault is internal
• Update or replace the relevant control unit only if testing or a manufacturer bulletin confirms it is the cause

Can I keep driving?

Nearby codes

• U352DGenericHigh Voltage System Interlock Circuit J
• U352FGenericHigh Voltage System Interlock Circuit J Low