aux lights relay diagram.

I want to wire up some aux lights, and it's a little different than I've done things in the past. I'd like three modes with a single double throw center off switch. - Aux lights off. (center) - Aux lights on (up, ignition on). - Aux lights on (down,high beams). Typically, I'd wire the positive side through a switch and to the relay trigger. But in this case, since the switched 12v and headlight 12v are already in the engine compartment, near the relays, near the lights, it seems it might be easier to switch the ground instead, which I've never done before. Does this circuit look like it will work for my purposes? http://paulor.smugmug.com/Image-Hosting-1/Forums/web/i-QXbw2g4/0/M/relay-diagram-M.jpg

Hmmm... Guess I can't edit my post. That should be Double PULL switch, not Double throw.

Quite correct though two things spring to mind. You show an SPCO (single pole changeover) switch in the diagram but from what you wrote after I'm sure you're aware. Second I hope your high beams only come on with the ignition, otherwise that could leave you with high beams and aux lights permanently on unless you remember to turn off that switch (or run the ground side through an ignition controlled relay).

And unless the 87a's go to something different, you could use a single relay and feed the hibeam & +12V switched through diodes. That's just to save a relay and space at the expense of 2 diodes. But I might use the 2 relays as shown for redundancy - ie, no need to carry a spare relay, the spare is in use and can be swapped upon failure if needed, else the other circuit used and relay replaced whenever convenient. [ Redundancy can be academic - the difference in reliability between 2 diodes and 1 relay as opposed to 2 relays may be insignificant - or maybe the 2 diodes and relay are more reliable. The question is, when the sole relay fails (hence no aux lights), is it acceptable (until it can be fixed)? Or is it better to be able to use "half" the circuit (with the still-working relay)? ]

howie ll wrote: ...you show an SPCO (single pole changeover) switch in the diagram ... Second I hope your high beams only come on with the ignition, otherwise that could leave you with high beams and aux lights permanently on unless you remember to turn off that switch

Yes, the headlights (hi or low) turn off with the ignition, after an adjustable exit delay. On the diagram, I tried using OmniGraffle for the first time. Gave up trying to find a good relay template, so I built my own, but grabbed a switch diagram from their templates... Should have made that one too!

oldspark wrote: ...and unless the 87a's go to something different, you could use a single relay and feed the hibeam & +12V switched through diodes.

Not following how to do this... If I feed both the switched 12V and high beams through diodes into 86, then I would loose my 'switched with high beam' functionality. 87a would be an inverted output, not sure how that would help, but I'm not an expert on relays, which is why I posted here!

Yes you are right. I overlooked the DPST switch... Ignore my entire last reply. (Except for the bit about me preferring the 2 relays anyhow, ie, iac pfbz's diagram...)

pfbz wrote: I'm not an expert on relays, ...!

Yeah, right.... You nailed their logic. (And me to a cross!)

Who needs to be an expert? They are either switches or changeover switches, functions to increase current, change current flow or polarity reversal. As basic units.

A practiced Expert? Not if self-taught or tutored sufficiently - at least the logic part. But Howie, the question is, "can an expert be wrong"? Alas, it's past my bed time. Goodnight.

Of course we can. Go back to burying the FB111s in that field.

I believe this may help.. This is how to set up a three (3) position switch. One is to have the lights come on automatically when triggered by another power source, ie: reverse lights/parking lights. Two is off all the time Three is turn them on independently. On the Switch

-One side goes to fused ignition power (on the diagram it is written for constant power, not ignition switched.)
-Middle goes to trigger post 86 on relay
-Other side goes to what you want to tap into (ie: reverse lights)

On the Relay

-30 goes to fused 12v power
-86 goes to middle terminal on switch
-85 goes to a ground
-87 goes to Aux Lights

This is the correct Diagram to use with the wires going to where I just mentioned. These are the switches I used. http://www.allelectronics.com/make-a-store/item/RS-146/SPDT-CENTER-OFF-ROUND-ROCKER-SWITCH/1.html