14Sport

A diode can short in an "open" or "closed" position effectively. Meaning it can act like a fuse or a wire conductor, depending on the failure mode.

I think I just figured out a way to use dual relays without a diode. I'm at work and don't have MS Paint (yeah, I use the good sh*t...lol) so I will draw it out tomorrow at home, but what I was thinking was:

Wiring the SPST relay as you do for all accessories. Then placing the SPDT between the oem reverse feed and the SPST. Tap the oem feed to pin 30 (this was a revelation!). Run pin 87a to pin 85 on the SPST. Tap the switch wire feeding the SPST to pin 85 of the SPDT. Pin 86 to ground. Woot! Woot! I think that will work. Completely isolates the oem wiring and won't turn on the reverse lights. Can you picture the circuit?

smittycm

If I'm tracking correctly, wouldn't this also power on the reverse lights when the switch is turned on? This would require the switch to be capable of the reverse lights draw. Not a big deal, but one of the benefits of using a relay to begin with is the low amp draw in the cab of the vehicle. It also means the reverse lights would come on when I hit the switch, but I'm only looking for the aux lights to come on when I hit the switch. Reason being is I want to be able to light up the rear area of the vehicle while it's turned off (e.g. camping) and so I'd want to minimize the draw on the battery.

Maybe I'm losing something in translation, or maybe it's as I've stated above and just not the solution I'm looking for. I think your other schematic may work better for what I'm looking for unless I'm mistaken. To make sure I'm not losing something in translation, can you correct and/or confirm the following info and I'll draw it out?

SPST
86: ground
85: 12v Switch
87: Aux Lights
30: Battery (constant)

SPDT
86: ground
85: 12v Switch (same wire feeding pin 85 on SPST)
87: empty
87a: Pin 85 of SPST, and 12v feed for OEM lights
30: OEM 12v reverse feed

14Sport

Yeah I hand drew it and I don't think it is going to work. When you hit the switch it disconnects pin 87a and connects pin 87 to pin 30 on the SPDT. That part is good. And the reverse wire feeding the control positive of the SPST when the switch is off is also good. Where it goes wrong is when I have to jump the 12v wire from the switch to pin 85 of the SPDT as well. Thus when the switch is off and you go into reverse, the current flows through the SPDT and activates the control circuit of the SPST and turns on the aux. But because of the jumper, it feeds back to pin 85 of the SPDT and shuts the SPDT back off. :( Ugh. Back to the drawing board.

14Sport

Sounds like the 3 way switch would be perfect for you. It provides everything you need. Are you against using a 3 way switch?

I can easily do it with 3 relays but that is probably too complicated for most people to want to try.

smittycm

Not necessarily against a three-way switch, but I already have a rocker switch in my A-pillar pod I was planning on using. I added the diode to the following location in your 2nd schematic using two relays. Would this not work?

14Sport

Yes. That is where you need to put the diode. Good job.

smittycm

Awesome. Thanks again for the schematic. Now I just need to track down the correct diode.

RC3

I have used some diodes from the Rat Shack rated at 6 amps & 50 volts. RS part number is 276-1661. The same thing is available at Fry's Electronics, but I don't have the part number for that one.

14Sport

I'm still trying to eliminate the diode altogether. I have an idea that I believe will work and will draw it up tomorrow. It sometimes is a slow process and takes several iterations to get there. We will see what tomorrow brings. Thanks again, guys, for the feedback. It really helps the creative process.

smittycm

Thanks. I'll definitely look into that.

I'm farting around with it too. Kind of fun, almost like a puzzle to solve. haha. I'm such a dork.