This bulletin applies to 2016-2020 Buick Envision vehicles that feature an unstable or rough idle that changes with electrical load. The cause may be unstable output from the generator field terminal input to the ECM.
If this condition is present, first check for and diagnose any DTCs. If none are present, perform rough idle diagnostics in GSI. If nothing is found, loosen and settle the engine and transmission mounts. If the condition persists, allow the engine to run until hot, shot off and let sit for 10 minutes. Restart with the HVAC set on MAX A/C and high blower fan and note if the unstable idle is present. If so, turn down the fan and switch the A/C off. If the condition is lessened, replace the generator and the generator cable.
The new generator is available as P/N 13535007 and the generator cable as P/N 84912343.
