Sub-panel with ground rod

Service equipment grounded to city water pipe and 4 wires (2X120V, neutral and ground) from the distribution panel going to the detached garage sub-panel. Garage has a ground rod in addition to the ground from the service equipment; is that proper?

Yes, the sub-panel needs to be connected to a grounding electrode system (GES) since it’s a detached structure. A GES can be ground rods, or a CEE or other electrodes. Unless a single rod is 25 ohms or less you would need two rods. Also it would get connected to the EGC bus not the neutral conductor.

Thanks Robert for your quick response!
I could not confirm where it was connected because I did not remove the cover. It had pointy screws holding it and the disconnect beside (with the pennies) didn’t encourage me either…

Pennies, yuck. Improper grounding might be the least of the problems.