Trigger a relay when running

[runningslow]

So, I have the cheap aftermarket ebay headlights with the small auxiliary projector light. I didn't want to mount a switch on the dash and I don't have factory fog lights, so currently, I have those lights wired such that they turn on in Accessory by tapping the power going to the radio to trigger a relay. This way they somewhat function as daytime lights, since they were pretty useless for lighting the road. Probably not the best idea, since they come on anytime I park and want the radio on.

Where would be a good place to tap so they come on as an iginition siwtched source?

Better yet... is there a way I could get them to only come on when the truck is actually running? For instance, a source that could detect alternator output? Connecting directly to the alternator charging circuit would probably drain the battery when its not running, though, since the relay would see a constant current from the battery, even if the alternator isn't active.

I'm going to add fog lights, and I think I'm going to wire them in a similar fashion, too.

 

[strvger]

chances are some of the harness is already in your tuck. maybe go to the local jy and find an rbv that has the fog lights and just pull that switch, relay, and wiring harness. then just install it in the correct location in your truck. will look and function as factory.
just a thought.

 

[--weezl--]

you can connect it to the tach output on something under the hood, should work...

there are lots of key on power sources that would work much better IMO, how often do you park with the key on, but engine off? when i park and want the radio on, i turn it to accessories, which uses much less battery

alternately, you can wire them to your park lights (corner marker)

 

[runningslow]

you can connect it to the tach output on something under the hood, should work...

there are lots of key on power sources that would work much better IMO, how often do you park with the key on, but engine off? when i park and want the radio on, i turn it to accessories, which uses much less battery

alternately, you can wire them to your park lights (corner marker)

I have them wired to come on currently with accessory (relay tapped to radio). That's the problem.

What would be a a good key on source to wire them to?

 

[--weezl--]

Heater panel you could tap into, I am a fan of pulling power from fuse boxes, grab a test light or multimiter, and start probing and flipping the ignition...