Wiring for auxiliary rear lights


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This is the setup I run for powering my auxiliary reverse lights. If you choose to run them off your existing backup light line but don't always want them to come on when you hit reverse or if you want to be able to have them on full time the diagram on the left is the one you want.

If you want to use a relay to switch the heavy current for the lights use the diagram on the right.

Either way you need a single pole, double throw (SPDT) switch with center off. That gives you three options, constantly on, never on, or on with your factory lights.

The relay diagram is how I do it. That way the reverse light switch is never carrying the heavy load of the extra lights. I found out the hard way that the stock switch may do fine with only two 1156 bulbs but adding 70 watts of load shortens the life of it a lot.

Be sure to fuse the power lead. The "tractor" lights are 35 watt, two of them will need a 10 amp fuse. 50 watt halogens will need 15 amps and 100 watt halogens will have to have a 20 amp fuse in the line.

My thanks to Chuck Smith for doing the diagram up in a format that I could post here. My original file was too big.



2000 Club Member
I'm trying to figure out how to do this yet isolate my back-up alarm when I've got the lights turned on. I'm thinking a relay to cut out the backup alarm when the switch is thrown, I guess I could use the same exciter wire as to the flood relay. Are there relays that open circuits when activated?
If you wire your backup alarm off the truck reverse lights,and use a setup like Alan's above,then the alarm is isolated when you throw the switch for the backup lights.It only comes on when the truck is in reverse.


2000 Club Member
In my case I've replaced the back up lights with 4" flood lights on my cab & chassis. I'm going to set them up so they can be switched on in addition to the reverse switch. If I put a relay on the alarm that opens when excited, this should work.
Yet another great post from Alan, (enter brown-nosing comments here).

Thanks. I have been trying to figure a way to hook them up off the batt and not the back up light circuit, you cave me a great idea.

Use the back-up light circuit to trigger the relay to turn them on.