Buick Idle Is Unstable

Oct. 25, 2022

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.

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.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of  specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.

About the Author

Information courtesy of Mitchell 1

Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.

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