Improving GMC brake booster vacuum

April 15, 2024
Some owners of 2018-2021 GMC Terrain vehicles equipped with an LTG or LYX engine may comment on a Service Brake Assist message.

Some owners of 2018-2021 GMC Terrain vehicles equipped with an LTG or LYX engine may comment on a Service Brake Assist message.

DTC P0557 may be found stored. The cause may be inconsistent in-rush current provided by the 5V reference during the start/stop crank event.

Replace the power brake booster vacuum pipe with the later version, containing a sensor that is more robust against in-rush variation during the start/stop crank events.

The correct part number for LTG engines is 84974393. The part number for LYX engines is 84974392.

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