OnStar Services

See also:

How to Check Lubricant
2500HD with 6.0 L All Other Series and Engines To get an accurate reading, the vehicle should be on a level surface. • For all 4.3 L, 4.8 L and 5.3 L 1500 Series applications, the proper leve ...

Heavy-DutyTrailer Wiring Harness Package
For vehicles equipped with heavy duty trailering, the harness connector is mounted in the bumper. The seven-wire harness contains the following trailer circuits: • Yellow: Left Stop/Turn Signal ...

Special Application Services
• Allison Transmission™ Vehicles Only: Replace external transmission filter at first engine oil change only. • Vehicles with Dual Wheels: Check dual wheel nut torque at 160 km/100 mi, 1 600 km/ ...