Switch Pod is a fan term referring to the two panels on either side of KITT's steering wheel which held buttons that activated many of the cars features. During the first two seasons, KITT had a total of twenty buttons (ten buttons each) on the switch pods. After KITT's upgrade, there were a total of thirty-two buttons (sixteen apiece) between the switch pods.
Season 1 and 2
The right Switch Pod carried KITT's more defensive functions like Turbo Boost, Silent Mode, and Lic Plates; the left switch pod carried KITT's more offensive functions like Rocket Fire, Smoke Release, and Grappling Hook.
The switch pods on KITT's dash stayed (more or less) consistent throughout Season 1 and 2. The left switch pod was actually fairly consistent for the first two seasons (the exception being Tear Gas being located where the Ski Mode button was normally. The right switch pod changed dramatically only during the last few episodes of Season 2 (most notably when Silent Mode, H.T.D.D. and Laser were introduced). For the most part, the button stayed where they were.
Season 3 and 4
After KITT was upgraded after his near destruction at the hands of the Drones, the switch pods were redesigned to hold more functions. The left switch pod carried the more computer-related functions (such as the Radar and System - Protect) while the right switch pod carried KITT's more offensive systems.
The switch pods in season 3 and 4 carried numerous function for KITT. Some buttons were seen or used once, then disappeared. While the left switch pod was (once again, more or less) consistent with what functions it had, the right switch pod carried too many buttons to count!