GM 6L90 6-Speed Heavy-Duty Automatic · GM/Chevrolet/GMC/Cadillac/Buick · Expert rebuild service since 1987. Lifetime warranty. Free diagnostic.
2006–2016 Chevrolet Silverado 2500/3500 HD; 2006–2016 GMC Sierra 2500/3500 HD; 2007–2013 Cadillac Escalade (6.2L); Cadillac CTS-V (6.2L supercharged); Corvette ZR1; behind 6.2L/8.1L engines
| Configuration | 6-speed automatic — heavy-duty full-size truck platform |
|---|---|
| Gear Ratios | 1st 4.03:1 · 2nd 2.36:1 · 3rd 1.53:1 · 4th 1.15:1 · 5th 0.85:1 · 6th 0.67:1 · Rev 3.30:1 |
| Fluid Type | Dexron VI ATF |
| Fluid Capacity | 12.5 qts total, 6.5 qts service refill |
Same TCC shudder pattern as 6L80 but under heavier towing loads. The 6L90's TCC works harder and wears faster in HD truck applications.
Symptoms: Shudder at highway speed under trailer load; TCC cycling; temperature warning
5-VFS solenoid wear under high-torque applications causes shift quality degradation.
Symptoms: Erratic shifts under heavy load; P0961-series codes
Maximum towing in 6th gear at elevated temperatures accelerates OD clutch wear in the 6L90.
Symptoms: Slip in 6th gear under maximum trailer load; drops to 5th on grades
Full disassembly. TCC replaced. VFS solenoids replaced. OD clutch pack with upgraded heavy-duty kit. All clutch packs and soft parts replaced. Valve body rebuilt. Converter flushed.
Dexron VI every 30,000 miles for HD towing applications. Auxiliary cooler strongly recommended for sustained max-weight towing.
Larger clutch packs, stronger planetary gears, and a higher torque rating (approximately 540 lb-ft vs 380 lb-ft for the 6L80). Otherwise shares architecture and many internal parts.
TCC shudder under tow load is the most common 6L90 complaint. Fresh Dexron VI helps if it's fluid-related; if shudder only happens under load, the TCC friction is worn and needs converter replacement.
$2,200–3,000. 2–3 day turnaround.
With a quality rebuild and upgraded clutch packs, yes. The 6L90 is used in Corvette ZR1 from the factory with the 6.2L supercharged engine.
Dexron VI ATF.
Free diagnostic, written estimate, lifetime warranty. Chicago's 6L90 rebuild specialists since 1987.
