GM Investigates OnStar Connectivity Loss on 2027 Cadillac Vistiq and Chevy Blazer EV

General Motors has issued an updated Preliminary Information Service Bulletin (PIT6534A, released October 2026) investigating a connectivity problem affecting certain units of the 2027 Cadillac Vistiq and 2027 Chevy Blazer EV. The issue can cause a complete loss of Wi-Fi connectivity, an unresponsive navigation display, and OnStar service failure — and it may persist even after the vehicle is shut off and restarted.

What's affected

• OnStar services: Remote access, emergency response, and connected services go offline.
• Wi-Fi connectivity: The in-vehicle Wi-Fi hotspot drops entirely.
• Navigation: The built-in navigation display becomes unresponsive.

The same issue has been reported on certain units of the 2027 Corvette, 2027 Chevy Equinox, and GMC Terrain, suggesting a platform-level telematics fault rather than a model-specific defect.

Interim repair

GM's engineering teams are still investigating the underlying cause. In the meantime, the bulletin provides an "interim repair" for technicians: reset the Telematics Communication Interface Control Module (TCICM) — the component that handles the vehicle's OnStar communications.

The procedure involves:

1. Disconnecting and removing the module's backup battery
2. Waiting five minutes
3. Reconnecting and reinstalling the components
4. Clearing any diagnostic trouble codes
5. Confirming the indicator light near the blue OnStar button illuminates green

GM estimates the reset takes roughly 30 minutes of labor. If the problem persists after the reset, technicians are directed to continue with normal diagnostic procedures. The company has not yet announced a permanent repair — the connectivity problem could return and require another module reset.

What Canadian owners should do

• If OnStar, Wi-Fi, or navigation has stopped working, contact your GM dealer and reference service bulletin PIT6534A.
• Vehicles can still be driven — the issue affects connected features, not drivability.
• Watch for a formal Transport Canada safety notice or recall if GM identifies a root cause.

For Canadian EV owners, OnStar is not just a convenience: it provides remote pre-conditioning (critical in winter), charging management, and the connected-car features that make EV ownership manageable. A silent loss of connectivity means no remote start, no charging schedule control, and no emergency roadside assistance — a real inconvenience, and a potential safety gap if the issue were to affect OnStar's emergency services.

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