GMC Canyon key fob battery

Separate remote fob

1. The remote is a small standalone unit. You will not need to touch the ignition key at all.
2. Turn it over: some older fobs use one small screw, newer ones just clip. Pry at the seam once any screw is out.
3. Replace the cell, keeping the + side where it was, and check the small metal tab still touches it.
4. Close the fob and test it. If it does not work, open it again and check the cell is seated flat.

A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.

Smart key (push-button start)

1. Most push-button fobs hide a metal backup key. Press or slide its catch and draw the key out first.
2. Look inside the empty key slot for a notch. Put the tip of the metal key or a small flat screwdriver wrapped in tape there and twist gently until the shell splits.
3. Before you take the old cell out, look at its face. Put the new cell in with the same side showing, and avoid touching both faces at once.
4. Reassemble, refit the emergency key, and check that the car sees the fob when you press start.

On many recent GM smart remotes a button on the side releases the key; the slot at the bottom is where the case opens.

A CR2450 is 24.5 mm across and 5.0 mm thick, much fatter than a CR2032. A thinner cell will rattle and lose contact, so buy the exact size.