help me find a hot wire!!!

I installed a 2 gallon air compressor in the bed of my truck, grounded it to the bed bolts but am having difficulty finding a strong enough hot wire to splice into that is ONLY ON when the motor is on, NOT accessory power.

I tied it into one of my daytime running lights and it ran for about 10 seconds before shutting off the compressor and flipping off that individual light. ONce i turn the ignition off and restart it the light re-illuminates but the same thing happens again. Its basically not a strong enough wire to pull off of...HELP PLEASE!

 

You need to use a relay. Pickup a basic automotive relay at your local auto parts store, they're only a few bucks. The relay will have 4 prongs, 30, 85, 86 and 87. The wire you tapped from your daytime running light, run that wire to pin #85 and ground pin #86. Run a power wire from your battery with an in-line fuse to pin #30, then connect the compressor to pin #87. That way, the compressor power in will come from pin #87 but will only be 'hot' when the DTRL are on.

What you did was not good for your electrical system. You should NEVER add to an existing circuit, just asking for trouble and/or electrical failures.

 

Doesn't the plug in trailer hitch lights do the same thing? Since they plug into your existing brake lights. Don't know, just asking.

 

X2.

And especially on that last part.

 

Yup, relay it. If you run too much power on a different circuit you will keep popping the fuse, and if you add a bigger one you could start a fire.

 

so if i understand correctly i will be adding a wire to my DTRL's and it will end in #85 and then i run a wire from #86 to a ground? do i still need the ground connected that is coming off the compressor? also what gauge wire is appropriate for these 2 spare wires?

thankyou for your help

 

This is almost the same, just wire up 87 to the compressor, and 86 to a switch or straight to accessory power.

When the truck has power to accessory it powers up 86 which switches 87 on straight from the battery. When there is no power at 86 the compressor loses power as well.