Service Transmission Messages Require Engine Control Module Reprogramming

Some 2022 Bolt EV and Bolt EUV models (Fig. 16) may have a “Service Transmission, Unable to Shift” message or “Service Transmission Now, Unable to Shift Soon” message displayed on the Driver Information Center along with an illuminated MIL. DTC U1345 (Engine Control Module LIN Bus 1 [or Bus 21]) and DTC U135A (Lost Communication with Shift to Park Range Actuator) also may be set.


Fig. 16


If these conditions are found, reprogram the Engine Control Module (ECM) with the latest software using SPS.

TIP: Do not perform the K20 ECM setup procedure. The service update requires reprogramming the ECM only. Performing the setup procedure may lead to unnecessary repairs.

Refer to K20 Engine Control Module: Programming and Setup in the appropriate Service Information. On the SPS Supported Controllers screen, select K20 Engine Control Module Programming and follow the on-screen instructions.

Be sure to record the Warranty Claim Code on the job card (repair order) for the warranty transaction submission.

Refer to Bulletin #22-NA-139 for additional information.

– Thanks to David Rase and Jonathan Johnson


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