Tesla High Voltage Interlock Loop (HVIL) Diagnostic Guide

Tesla High voltage interlock loop (HVIL) diagnostic guide

1. Introduction

1.1 What is HVIL?

High voltage interlock loop (HVIL) is a safety feature which protects people during the assembly, repair. maintenance and operation of a car. It is loop/circuit which will not allow the contactors to close when high-voltage connections becomes loose, disconnected or damaged. It also helps to protect driver and passengers in the event of accident. 

Tesla High Voltage Interlock Loop (HVIL) Diagnostic Guide

 

 

If the resistance changes, and the Voltage drop higher or lower than the maximum thresholds, BMS reports an HVIL alert.

If Car is Standby

BMS_f008_HW_HVIL

If car is standby, support, or Charge mode. The alert is reported as Fault. Car opens the contactors or keeps them open.

If Car is in Drive mode

BMS_w008_HW_HVIL

If car is in Drive. The alert is reported as Warning. Car does not open contactors to prevent loss of drive.

Please have a look on guide. Link

High Voltage Components

PTC Heater

Please check more details about PTC Heater Repair in another guide. Link

A/C Compressor

HV Battery

HV Junction Box

One of reason could be connection in Front Junction Box

Action to do - check all the connections on and in the front junction box

Rapid Splitter

Rapid Splitter connects to Battery, Charger Module, Rear Motor Inverter and Front Junction Box.

Drive Unit

Please check more details about Drive Unit in another guide. Link

DC/DC

Coolant Heater

Isolation Procedure

Isolation procedure guide. Link

Code

Possible alert Code

  • BMS_f036
  • BMS_w036
  • BMS_f008
  • BMS_w008
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Disclaimer: Tesla, Inc. was not involved in the creation of this document. Tesla did not provide us any info. Tesla did not edit, review or authorize us. We gather this information from Tesla official website and other resources.

Note: It is your responsibility to double check and confirm that the procedures/info mentioned in this blog are applicable to your specific car before performing them. Please contact us or our workshop partner to make sure/confirm. We will be happy to help you.