ATSG CONFIRMED FIX - JANUARY 2024
2006 Chevy 2500 6.6L Allison 1000
Complaint: Shortly after completing rebuild, transmission started slipping in 4th gear and setting code P0777 for Pressure Control Solenoid B stuck on.
Cause: Faulty Aftermarket C2 clutch piston
Correction: Replace piston with OEM piston
Part numbers related to the repair: NA
Year Make and Model of the Vehicle: 2006 Chevy 2500 6.6L
Mileage: 132,000
Shop Name: Falcon Transmission
Transmission: Allison 1000
Additional Notes: Vehicle came in for complete rebuild. The technician used aftermarket rebuilt kit complete with new clutch pistons. Vehicle returned after a few days slipping in 4th gear and setting code PO777. During disassembly the tech saw that the C2 clutches were burnt and during an air check on the clutch drum noticed it was leaking past the piston. He rebuilt the clutch pack with a OEM piston air checked it again and sealed perfectly. Always when installing a new molded piston check the drag on the piston, usually undersized piston will install with very little drag.
Pictures/Diagram: check photo below of piston
Find thousands of Confirmed Fixes, Quick Reference Guides, Bulletins & Video Tutorials in the ATSG Member exclusive Tech Library along with unlimited calls into the tech hotline by joining ATSG today: https://bit.ly/ATSGmembership
