02 Camry - under hood fuse box- what are these?

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.

Anyone have any idea what these are?


Any chance at a decent clear picture of the components. The one on the right looks to have a diode symbol on it. Can’t tell much.

I asked the same. I’ll let ya know

Those are diodes. This is a 2003 ES 300, only has 1 diode.


I should have been clearer in my original post. We figured they are diode, but any idea how to figure out what system they are part of?

I’m going to pull up a 2003 and see if that helps any, @Nevada_545
thanks for that pic!

Those diodes are for A/C radiator fan relays. 4 cylinder has 2 diodes, V-6 has one diode.

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looked them up, that looks to be them. Thanks!!

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.

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