NHTSA Complaint #11598370 — 2020 GMC SIERRA 3500 POWER TRAIN

Complaint Details

ODI Number	11598370
Vehicle	2020 GMC SIERRA 3500
Component	POWER TRAIN
Date of Incident	July 1, 2024
Date Filed	July 2, 2024
Mileage	N/A miles
Crash	No
Fire	No
Injuries	0
Deaths	0
Vehicle Towed	No
State	IA

Consumer Description

driving 65mph when vehicle attempted to downshift itself for no reason when instead the rear axles locked up and made a massively loud bang as if axle fell off, let off gas, smoke pouring from rear tires, skidded about 8 feet, it released then locked up 2 more times within 30 secs before I could get off road out of traffic flow. mfd has a tsb for this issue(#21-NA-275 GM) not sure if its transmission or braking system Dealer service could not replicate and told me it was probably my trailer(wasnt traveling with trailer) no warnings, no codes occurred initially at 56000 mile, has happened 10 or 12 times since then. very scary, im afraid to drive or tow now that dealer mentioned trailer brakes.

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