An illuminated rocker switch is like a SPST toggle switch
with an extra terminal which allows the light to work. You might want to review the article on toggle switch wiring before proceeding. Also relays can be used to switch higher draw accessories to reduce switch load and voltage drop.
Toggle Switch Wiring
Most rocker switches are of the “single position, single
throw” variety. That is what we will be covering here. In one position the
switch is ‘open’ and no connection is made. In the other position it is ‘closed’
and the accessory is connected to power.
Most switches will be labeled “Power”,
“ACC” or “Accessory”, and “Ground”. The switch opens and closes the connection
between “Power” and “ACC”. “Ground” is connected to the vehicle ground and is
needed for the light to work. If your connections are not labeled, you will
need to test them with a multimeter or determine which is which through trial and error. Note most switches will not illuminate if they are on the 'ground' side of the accessory.
Here is an example of how you might wire up an auxiliary
fan. Note if terminal 3 “Ground” was not connected, the switch would still
operate the fan, but you would not get illumination. Note this is just an illustration of how the switch works. A fuse should usually be included, and a relay utilized in higher amperage applications.
If you are unsure of anything, we recommend having your
wiring work performed by a professional. Improper wiring can result in damage
to components and even fires.
Typical Project Materials:
Heat Shrink Butt Connectors and Disconnect Terminals
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