My dad is working on my moms 2002 Toyota Camry LE, 2.4L, 2xx,xxx miles.
They are fighting a battery draw, and in the process of checking things, dad came across the two items in the pics, that are not on any of them fuse box diagrams he (nor I) can find.
From what I’m seeing there appears to be two water (presumably coolant) temperature-activated switches, and a pressure activated switch (presumably A/C related) controlling three fan relays, along with the ECM poking it’s nose into all this business. The diodes are required to keep the circuits (controlling which fan(s) turn on for which conditions) isolated from each other. D1 looks different from D2 b/c D1 actually contains two separate diodes. D2 is lazier, just contains one diode.
My Corolla’s idle rpm control uses a similar diode arrangement to operate the idle-up (high idle rpm) function. Diodes are arranged to implement simple logic, so that if either the headlights and/or rear window defogger are turned on, idle rpm increases.