U352D

What it means

U352D is a generic code for a fault in High Voltage System Interlock Circuit J. The high voltage interlock loop is a low-voltage safety circuit that runs through high voltage connectors, covers and components to confirm they are all properly connected. The control unit that monitors this loop saw an open circuit, a short, a signal out of range or a loss of the expected interlock signal, so it set the code. Which components sit in circuit J, and which module monitors it, depends on the vehicle, so check the manufacturer wiring information.

Symptoms

• Hybrid or electric system warning light, or a general fault warning on the dashboard
• Car will not go into ready mode or will not start
• Reduced power or limp-home mode while driving
• High voltage system shuts down while driving or the car loses drive
• Charging will not start or stops part way through
• Other stored codes for high voltage components or lost communication

Possible causes

• Interlock connector not fully seated, or a loose or damaged interlock pin or terminal in a high voltage connector on circuit Jlikely
• Open circuit or chafed wiring in the interlock loop, for example after accident damage, previous repair work or rubbing on bodyworklikely
• Corrosion or water ingress at an interlock connector or component housingpossible
• Service disconnect, cover or high voltage component not refitted correctly after recent workpossible
• Fault inside a high voltage component that carries the interlock loop, such as an inverter, charger, compressor or battery packpossible
• Fault in the monitoring control unit or its software, or an outdated calibration where the manufacturer has issued a bulletinrare

How to diagnose

1. Make sure the work is done by someone trained in high voltage systems. Follow the manufacturer's isolation and safe-working procedure before touching any orange cabling or high voltage connectors.
2. Read all stored codes and freeze frame data. Note whether the fault is current or historic, and look for related high voltage, communication or isolation codes.
3. Find out from the manufacturer wiring information which connectors and components are in interlock circuit J for this model.
4. Visually inspect those connectors, covers and the service disconnect for correct seating, locking tabs, damage, heat marks, water or corrosion.
5. Check the interlock wiring for chafing, crush damage or previous repairs along its route, especially if the car has been in an accident or recently serviced.
6. With the system isolated, test interlock loop continuity and resistance, and check for shorts to ground or supply, against the manufacturer's specification.
7. Check for any software or calibration updates for the monitoring control unit that relate to this code.
8. Clear the code and test the car, then recheck. If the fault returns, work through each component in the loop in turn, following the manufacturer's test procedure.

How to fix

• Reseat and secure the affected high voltage connector, and replace any connector with a damaged lock or interlock pin
• Repair or replace damaged interlock wiring, and secure it so it cannot rub again
• Clean or replace corroded connectors and fix the source of any water ingress
• Refit the service disconnect or covers correctly, using new seals or fasteners where specified
• Replace the high voltage component that carries the faulty interlock, once testing proves it is at fault
• Update the control unit software or calibration only where the manufacturer lists it as a fix for this fault

Can I keep driving?

Nearby codes

• U352CGenericHigh Voltage System Interlock Circuit H High
• U352EGenericHigh Voltage System Interlock Circuit J Performance