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2026 GMC Sierra 2500 HD AT4 - OEM Repair Service Manual
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 2
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 3
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 4
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 5
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 6
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 7
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 8

Product detail

SKU: JD63253

Year

Sub-model

AT4

Engine

6.6L V8 (Y) L5P Turbocharged DIESEL FI

Description

Trim level and powertrain change the numbers that matter: torque specs, wiring, fluid capacities, part numbers. A generic Sierra 2500 HD guide gets you close. This is the documentation for your exact 2026 GMC Sierra 2500 HD AT4, not a nearby approximation.

The 2026 GMC Sierra 2500 HD AT4, 6.6L V8 (Y) L5P Turbocharged DIESEL FI, has its own OEM-Authorized documentation set. Jayda pulls it from GMC's source: component locations, diagnostic procedures, wiring schematics, labor times, fluid specifications, OEM part numbers, torque specs, TSBs, and recall information specific to this configuration.

The right procedure for this Sierra 2500 HD. Not a platform approximation.

Everything you need for a successful repair

All 12 OEM data features included with Pro Tech, grouped by how you'd actually use them.

  • OEM Repair Procedures
  • Diagnostic Trouble Codes
  • Wiring Diagrams
  • Component Locations
  • Specifications & Torque Values
  • Fluids & Capacities
  • OEM Parts Data
  • OEM Parts Illustrations
  • Labor Time Estimates
  • Maintenance Schedules
  • Technical Service Bulletins
  • Recalls
2026 GMC Sierra 2500 HD AT4 - OEM Repair Service Manual
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 2
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 3
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 4
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 5
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 6
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 7
2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog - Image 8

2026 GMC Sierra 2500 HD AT4 6.6L V8 (Y) L5P Turbocharged DIESEL FI OEM Repair Service Data Manual and Parts Catalog

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Chose your plan
  • OEM-Authorized repair procedures, wiring diagrams, DTC codes, and torque specs for this exact vehicle.
  • Ask like you'd ask a mechanic and get the OEM procedure, not a menu tree.
  • Every answer includes a citation you can click and verify.
  • Licensed from MOTOR, the data source trusted across the industry since 1903.
  • Works right from your phone at the vehicle, no walk back to the desk.
  • If it's not in the data, Jayda says so instead of guessing.