How to Jump Start a GMC Sierra 2500HD/3500HD

1. Make sure the other vehicle has a 12-volt battery with a negative ground, and park the two vehicles close but not touching.
2. Set the parking brake on both vehicles, put automatic transmissions in P (Park), and keep a four-wheel-drive transfer case in a drive gear.
3. Turn the ignition off on both vehicles and switch off or unplug unneeded accessories, the radio and lights.
4. Connect the red positive (+) cable to the discharged battery positive (+) terminal, then the other end to the good battery positive (+) terminal.
5. Connect the black negative (–) cable to the good battery negative (–) terminal.
6. Connect the other end of the negative (–) cable to the discharged battery negative (–) grounding point.
7. Start the vehicle with the good battery and let it run for a while, then try starting the disabled vehicle.
8. To remove the cables, reverse Steps 8–11 in exact order, then let the started vehicle idle for several minutes.

• The discharged battery positive (+) terminal is under a cover on the passenger side; open the cover to reach it.
• Do not connect the negative cable to the dead battery's negative terminal because this can cause sparks.
• If the vehicle will not start after a few tries, it probably needs service.

Source: 2026 GMC Sierra 2500HD/3500HD owner's manual, PDF pages 353, 354, 355. Steps are summarized in our own words (AI-assisted, checked against the cited pages 2026-10-18). Other model years can differ; your manual has the final word.