Toyota 2012 Prius C Owner's Manual page 417

4-3. Do-it-yourself maintenance
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Replacing the battery (vehicles with a smart key system)
STEP 1
STEP 2
STEP 3
398
Take out the mechanical key.
Remove the cover.
To prevent damage to the key,
cover the tip of the screwdriver
with a rag.
Remove the depleted battery
using a small flathead screw-
driver.
Insert a new battery with the
"+" terminal facing up.