GMC Sierra 2500HD Transmission Repair Chicago
Expert GMC Sierra 2500HD transmission service in Chicago. Free computer diagnostic, lifetime warranty on rebuilds, all years.
Expert GMC Sierra 2500HD transmission service in Chicago. Free computer diagnostic, lifetime warranty on rebuilds, all years.
2001–2010: Allison 1000 6-speed (Duramax diesel); 4L80E or 6L90 (gas) 2011–2019: Allison 1000 continued; 6L90 for gas 2020+: Allison 10L1000 (Duramax) or 10L90 (gas)
Same approach as Silverado 2500HD. Allison TCC: converter and valve body inspection. Gas 6L90: SRV sleeve repair first. Allison 10L1000 issues: solenoid inspection, PCM update check.
Allison: TES-295 Dexron HP 6L90: Dexron VI
6L90: 3–4 days. Allison: 4–6 days.
"Honest diagnosis, fair price, and the repair was done right. Chicago Transmission has been my go-to for years. Wouldn't trust anyone else with my car."
"The free diagnostic alone was worth the trip. They found the problem fast, gave me a written estimate, and completed the work on time. Exceptional service."
"Family owned and it shows. They treated my car like it was their own. The lifetime warranty on my rebuild gives me total peace of mind. Highly recommend."
Both are capable transmissions. The Allison has a stronger clutch pack design; the 6R140 is more calibration-sensitive. Both are rebuildable.
That's TCC slip in the Allison under load — a converter issue. Bring it in before you damage the valve body.
4–6 business days for a full rebuild.
Yes — diesel and gas Sierra 2500HD and 3500 are a regular part of our business.
Yes — we have a heavy-duty flatbed. Free within 15 miles with repair over $500.
Same-day appointments available. Honest estimates, no surprises. We've been doing this since 1987.
