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May 19, 2026 Service bulletin

This service alert supersedes the previously issued service alert listed below

Mazda technical service bulletin SA-034-26 for 2019-2026 Mazda MAZDA3, 2021-2025 Mazda CX-5 and 2021-2023 Mazda CX-9 and others.

Bulletin number
SA-034-26
Component
Electrical system
Summary
This service alert supersedes the previously issued service alert listed below. The changes are noted in Red text. SA-047/25 10/07/25 DESCRIPTION When the Telematics Control Unit (TCU) replacement is necessary due to a failure, use MDARS to activate the new TCU after replacement. Use the information in this service alert to initialize the new TCU until the procedure on MGSS is updated. CAUTION: DO NOT swap TCU with another vehicle as the TCU is VIN locked after activation. A TCU swap with another vehicle will disable Connected Services on both vehicles. • If TCU activation is not performed, connected vehicle functions will not operate. This will have a negative impact on the customer because they will need to return to the dealer for repairs. • If the Telematics Control Unit (TCU) replacement is necessary, check "Vehicle Communication Line Status Reference" status detail first. The TCU can only be replaced under the following "Status Detail" conditions: Open Completed (OK) ○ Closed Completed (OK) ○ ○ If the TCU is replaced under the following "Status Detail" conditions, the customer may not be able to enroll into the replacement TCU. Processing (NG) ○ Request Failed (NG) ○ Open Failed (NG) ○ Flag Setting Failed TCU Activation 1. Install the new TCU.

Owners of these vehicles have filed 248 complaints in the electrical category.

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