Aux backup lights help: SPDT switch to relay, how?

I am trying to wire my reverse lights the right way. On the SPDT switch, the center post is the output, the left side post wired to the back up light circuit, and the other to a 12 volt ignition source. My question is how do I wire the relay? Do I just connect the output from the switch to the relay like I was wiring foglights? I'm confused. Will this diagram work? Ignore the highbeam lowbeam, and replace with factory backup light wire

But why do I need a standard SPST switch and a SPDT switch? Thanks

 

[yob_yeknom]

Okay, I'm really confused here. What exactly are you trying to do? I'm assuming you want to be able to wire the new lights to do all of the following:

-be able to turn off all the time
-be able to switch on all the time
-automatically come on and off with the stock back-up lights

Correct?

 

[Byrd91]

If what monkey boy said was correct all you will need is one SPDT switch. Like you said the middle is output so that will go to the INPUT of the relay. One of the other posts on the switch will go to the reverse circuit like you said, and the other post will go to either an on with ignition or on all the time depending on what you want. Now the relay will just be wired like any other relay, with ground, power, input (from the center of the switch) and power out to lights. Oh yeah, and if your switch is lighted it'll have a ground too. So this will give you:

1) Off in the middle position
2) On with ignition or all the time with one position
3) On with backup lights in the other position

 

[beavis195]

Just finished wiring. I couldn't find a SPDT switch that was lighted, so I added another SPST switch that is lighted so I know that they are on. That way I know when they are on. This is cool. I'm not blowing fuses like last time. Thanks guys.

 

[mattadams]

ok so I'm confused... so you have two switches for this? I'm trying to figure out how to do this myself so I'm trying to figure it out, LOL.

 

[yob_yeknom]

He didn't have to use two switches, he just couldn't find the type of switch that he needed to use that lights up. He wired in an extra switch (always left on) simply so that it would light up when the lights were on.

I'm working on drawing a cheesy diagram right now of what you need.

 

[mattadams]

ahh ok sounds good... I'm rewiring all my lights in my truck and what I want to happen is to find the best, safest way, to have my reverse lights come on either with a switch (standard 2-position on/off switch) or when I put the truck in reverse. Most diagrams I've foudn either use a 3-position switch so it is either coming on when the switch is in one position (on) or when the switch is in the other position and you are in reverse, or they have a switch that says "when turned on, lights can come on but only with reverse lights". It's a fun project!

 

[yob_yeknom]

AUXILLARY BACK-UP LIGHTS WIRING DIAGRAM

 

[yob_yeknom]

With that setup, it works like this:

When the switch is in the ON position, it energizes the relay, pulling the contact over to close the circuit and the lights come on.

With the switch in the OFF position, no current is sent to the relay so the circuit stays open and the lights can't come on.

With the switch in the AUTO position, power is only sent to the relay when power has been applied to the stock back up light circuit (put tranny in reverse). Again it closes the contact and the lights come on, then when power is removed from the stock circuit (take tranny out of reverse) it takes it away from the relay and opens the circuit so the lights go off.

By using the relay, no extra strain is put on the stock wiring because all the power for the aux. lights comes straight from the battery. By wiring the ON position to an ignition power source, you can't accidentally leave the lights on when the key is not on and drain the battery.

I hope the picture and the definition clears up any questions anyone may have.

 

[mattadams]

ahh ok you've got it hooked up with a three-position switch instead of a two-position... thats the way that makes the most sense but not the way I want it, heh heh. Thanks anyways!

 

[Okrazie1]

Matt, the diagram monkey boy drew will work for you, but if I understand you correctly, you don't want an off position to disable the lights completely. If this is the case, use a SPDT "On-On" switch. This type of switch eliminates the center position and will accomplish what you want to do.

 

[Diff Whack Daddy]

Here is what I did.

I used a 5 pin relay. One goes to ground, one to the reverse light ckt to energize the relay, one directly run to the battery through a fuse(this one is in contact when the relay is energised by putting the truck in reverse), and the last one through a switch, then a fuse to the battery(this one is in contact when the relay is deenergized. The last pin goes to the aux reverse lights. This allows me to turn the light on at any time without sending current through the rest of the ckt but they always come on in reverse.

 

[mattadams]

Diff whack, yeah thats what I'm talking about... what kind of relay did you use? Do you remember what wires went where? I've got a 5-pin relay but its set up so that the two pin's are going out to the lights, for example if you want one wire for each light?
I swear I'm laughing my ass off over here since this is the first time I've been stumped on a lighting problem with my own vehicle, LOL.

 

[mattadams]

ooh, just had a thought. Hypothetically, I could take the 87 and the 30/51 wires and reverse them and achieve the desired results, correct? I'm kind of new to relays so correct me if I'm wrong, LOL. The way it is now is that the relay I've got said the 30/51 pin is fused power from battery, and power to lamps is 87/87a (two pins). I'm wondering if I could switch those and the relay would know what I was talking about...
I feel like such an electrical dumbass sometimes, LOL.

 

[Diff Whack Daddy]

I actually used an old ABS relay since after the solid axle I no longer have it. As soon as my wife gets home with my truck, she was out of gas, I will check the relay and give you all the pin numbers and stuff.

 

[Okrazie1]

Here's a generic diagram of Diff Whack's setup:

I personally would not recommend this configuration because you have to run the current powering the lights (when the switch is controlling them) through the switch. In the configuration monkey boy drew, the switch is controlling a low current (the coil of the relay), and letting the relay's contacts handle the higher current draw of the lights.

 

[Diff Whack Daddy]

Here is a better drawing and the relay I used is a Ford relay that you can find in your power distribution box under the hood. I used the ABS one since it was no longer operable anyway.

 

[mattadams]

allright I've figured out how I'm going to do it. Rather then mess around with switches, relays, bla bla I'm just going ro tun the wire from the switch and splice it in with the wire that runs from the reverse lights to the relay. This way the relay will turn on with power either from the switch or the reverse lights. What I'm going to do is install two diodes, one from teh reverse light wire to the relay before the junction point, and one from the switchw ire to the relay wire, before the junction point. This will prevent the switch from turning on my stock lights and prevent any weird wattages going where they shouldn't go.

Diff whack, I may give that a try before doing it my other way, I'll let you know what I can come up with!

 

[Diff Whack Daddy]

Matt, what you are doing was my original plan, but then I found that 5 pin relay and found I can do the same thing with less components, ie the diodes. Hope it all works out for you.

 

[mattadams]

heres the diagram (I had a friend from the f150 board draw it up for me since I'm horrible with drawing diagrams)