• Fixes to help ensure proper functionality for heating and cooling features
Chevrolet technical service bulletin 662.21 for 2025 Chevrolet Silverado 1500 and 2025 GMC Sierra 1500.
- Bulletin number
- 662.21 (662.21)
- Component
- Unknown or other
- Summary
- • Fixes to help ensure proper functionality for heating and cooling features. • Improvements to night mode lights for shifting gears. • Fixes for Daytime Running Lamps turning on when set to Off. • Fixes to help prevent erroneous missing key messages on driver display. • Fixes for accuracy of low tire pressure alert. • Fixes for speed threshold for pedestrian alerts. • Improvements to start reliability and reduced check engine light activation • Improvements to turbo system diagnostics • Improvements to reliability when extending the running boards on your vehicle • Improves transmission diagnostic software. • Reduces unnecessary check engine light activations. • Fixes to help extend coolant valve life through diagnostic changes
Vehicles covered
- Chevrolet Silverado 1500 2025 2025
- GMC Sierra 1500 2025 2025
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