• Improves transmission diagnostic software
Chevrolet technical service bulletin 663.20 for 2026 Chevrolet Tahoe, 2026 GMC Yukon and 2026 GMC Yukon XL and others.
- Bulletin number
- 663.20 (663.20)
- Component
- Unknown or other
- Summary
- • Improves transmission diagnostic software. • Reduces unnecessary check engine light activations. • Improved braking performance and reduced unnecessary messages and alerts
Vehicles covered
- Chevrolet Tahoe 2026 2026
- GMC Yukon 2026 2026
- GMC Yukon XL 2026 2026
- Cadillac Escalade 2026 2026
- Chevrolet Suburban 1500 2026 2026
- Cadillac Escalade ESV 2026 2026
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