Rivian R1T (Gen 2) Diagnostics
Classification: Electric Vehicles Equipment
Hardware operational fault codes, protection alarms, LED blink sequences, and step-by-step diagnostic fixes for the Rivian R1T (Gen 2).
Indexed Fault Codes for R1T (Gen 2)
Step-by-step resolution manuals and root cause matrices
High Voltage Isolation Fault
BMS_a171 is triggered when the Battery Management System detects that insulation resistance between the 400V/800V High Voltage DC bus and the 12V chassis ground drops below the safety threshold (typically <500 ohms/volt or <100 kOhms total), resulting in drive system shutdown to prevent electric shock.
HV Isolation Contactor Lockout
Error BMS_b047 triggers when the Battery Management System detects high-voltage isolation resistance falling below safe operating thresholds (<500 ohms/volt or roughly <200 kOhms to chassis ground). To protect the chassis from electrification, the BMS commands pyrofuse integrity checks and main contactor separation, downgrading the drive unit into Turtle Mode or an outright vehicle shutdown.