NHTSA Complaint #11461966 — 2017 CHEVROLET BOLT EV

Exact details UNKNOWN. Description: About 2 yrs ago, releasing the brake pedal started triggering rapid popping sounds from engine compartment. The popping sounds are rapid--maybe 4 or 5 per second--and continue for a few seconds or more, up to at least 30 seconds depending on ambient temperature and main battery charge level. Opening the driver side door following vehicle at rest can also trigger this popping noise. But mostly the popping occurs when brake pedal is fully released during operation of the vehicle. GM responded initially to reports of this issue by replacing brake control parts; but more recently, according to a service bulletin (see uploaded document), a software update may be used to fix the problem. Since many vehicles which have the problem are out-of-warranty, GM charges owners for applying this software update. How can we be sure that this issue is not safety-related? If this is a software defect in the braking control system, why is warranty coverage required for the update?