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

1. Check that the other vehicle has a 12-volt battery with a negative ground system, park the vehicles close but not touching, and set both parking brakes.
2. Turn the ignition off on both vehicles and switch off or unplug unneeded accessories and lamps.
3. Connect one end of the red positive (+) cable to the discharged battery positive (+) terminal, which is under a cover.
4. Connect the other red end, without letting it touch metal, to the good battery positive (+) terminal or remote positive (+) terminal.
5. Connect one end of the black negative (–) cable to the good battery negative (–) terminal or remote negative (–) terminal.
6. Connect the other black end to the discharged battery negative (–) grounding point.
7. Start the vehicle with the good battery and run the engine for a while, then try starting the dead vehicle.
8. Remove the cables in exactly the reverse order, then let the started vehicle idle for several minutes.

• Put the automatic transmission in P (Park); with four-wheel drive, keep the transfer case in a drive gear, not N (Neutral).
• Do not connect the negative (–) cable to the dead battery's negative (–) terminal because this can cause sparks.
• If it will not start after a few tries, it probably needs service.

Source: 2022 GMC Sierra Denali 2500HD/3500HD owner's manual, PDF pages 375, 376, 377. 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.