Q's on wiring a reverse flood light

[DFrank]

I got a halogen lamp that I plan to wire to the back of my lumber rack.



I would love to wire it with a 3 position switch that would be on/on with reverse/ or off.



A quick trip to the auto parts store did not result in the purchase of a switch. It would seem like a dome switch with on/off/door positions would be the ticket.



Any suggsetions on where to find that or something that would work?



I am probably over designing. I might be perfectly content w/ a simple toggle, but I like the idea of them coming on with the reverse lights, as well as just keeping all of my options open.



I assume I should use a relay somewhere, but don't know alot about them.



I see lots of unused relay spots in the fuse box. Is it easy to utilize these?



Thanks for your tips.

 

[bighammer]

I think a SPDT (single pole double throw) would do the trick. Center is off, and one side could be on, and the other on w/reverse. Sounds like a good idea.

 

[DFrank]

thanks, bighammer. Do you think that might be found at a checker type parts store or where would you suggest?



Still wondering if I need to use a relay.

 

[SOLER]

Get a relay. You'll be better off, as your choices for 20-30 amp switches are limited. I have discovered like you that there are 3-4 spare fuse spots in the fuse block, and each go to an spare relay spot. I haven't played with it enough yet, though. I would think that your light would be fine with a 20-25 amp circuit.



How a relay works:

Relays are used mainly when you need something heavy-duty (20-50 amps or so) and your actual switch won't handle many amps (like 2-5 amps tops). You run the accessory and your switch to the relay, which has a heavy-gauge wire going to it from the battery. When you turn on your switch, it completes the circuit from the switch to the battery, and sends juice to the accessory.



Your switch:

One switch with on-off will suffice, and since you'll use a relay, 2-5 amps capacity should work fine. It will have either 2 or 3 poles. One to the battery, one to the switched side of the relay, and the 3rd will be ground. They are cheap and you'll have lots of choices (toggle, rocker, push, etc. , and you can get lit or unlit). If you buy a relay, it will have at least four poles on it. One will be ground, one will be battery, one for the switch, and one for the accessory. You'll usually get instructions with them, and are pretty easy to follow. The hardest part is running the wires all over. Sometimes you have to get creative there.



Your on-off switch will take care of the lights manually, but getting them to turn on when in reverse will require finding the circuit (wire) for the reverse lights. You can run a wire from the fuse block on the fuse that powers them, and run it to your "switch" pole on your relay. It will have a completed circuit again when it sees the signal from the reverse circuit, and send the juice out to the accessory.



So, to sum up, you'll need:

1. A 20-25 amp relay, depending on the requirement of your light

2. A switch

3. 12-14 gauge wire, black for ground, and red for battery

4. 14-16 gauge wire, for the accessory

5. 16-18 gauge wire, for the switch (both the switch, and the reverse circuit [these will run to the same pole on the relay])

6. An assortment of connectors to connect all the wires where they need to go



I made a diagram. I'll put in gallery.



SOLER

 

[DFrank]

SOLER- you rock. Thanks for taking the time to draw that.





Is it worth trying to use any of the available fuse and relay spots in the fuse box or should I get just use all aftermarket stuff?



I still don't quite understand what would be involved to use a 3 postion switch, that would allow for the light to be off even in reverse. I think it is unneccessary and I will wire it just like you show.



Thanks again, Dave

 

[SOLER]

No problemo



I didn't even think about you not wanting them to come on EVERY time you shifted into reverse. Hmmmm.



A 3-way switch would be the better alternative. Or, you could use a second switch.



3-way (as bighammer pointed out, a single pole, double throw):



Run the green wire (by the way, you can use whatever color wire you want, I just used different colors for illustration, but these are the colors I'd use, and I do recommend using different colors) to one of the switched poles on your 3-way switch. I haven't used many of these, but I think there will be 4 poles on it. One for battery, one for switch, and the other to be used as a "go-between" If there are two poles that look like they are on the same circuit, then run the green wire to one, and another green wire from the other side to the switched pole on the relay.



The easiest way, but not necessarily the cleanest, would be using a second switch. Just run this switch in-line with the green wire. Run the green wire from your fuse block to a pole on this switch, and then from the other pole to the switched pole on the relay. If you don't want a bunch of switches clogging up the dash, and since you don't need real easy access to this switch, you can mount it out of site somewhere.



A 3-way switch will most likely come with decent instructions, and will aid you in hooking it up. They just aren't as plentiful.



Let me know if I can be more help.



SOLER

 

[DF5152]

they way i did mine... . a relay and on-off-on switch. switch in up position back up lights triggered by reverse lights center they stay off switch in down position light are on manually.

 

[SOLER]

Use fuses

I forgot to mention something very important. Use fuses. It's best to use a 30 amp fuse in your "hot" wires, and use 20-25 amp fuses in accessory wires.



I haven't dug into my fuse block yet to determine how to wire into them (it's only a matter of time ), but if you go to tinkering with it, just be careful. And for safety's sake, and to avoid shorting anything out and/or setting off codes, unhook BOTH neg cables of the batteries before doing all this. It's best to use an ohm-meter to check continuity in circuits. This way you can check to see if it's wired right without having to unhook/hook-up the cables a bunch of times.



SOLER

 

[DFrank]

Thanks, I did get a self resetting circuit breaker for it. I found some relays at Napa, but don't quite understand the tiny little diagram that came on it.



If I can figure out how, I might try to post the schematic and ask some questions. It's too windy here today to want to do much outside anyway.

 

[DFrank]

I got the relay figured out, but not really sure where to tap revers light power. I'd love to just connect to the reverse lights and then add power from the switch elsewhere. I doubt the factory reverse wires are spout enough to add a big light to. Anyone think that would be OK.



Anyone know where to find the reverse light circuit up near the cab or engine?

 

[SOLER]

Originally posted by DFrank

I got the relay figured out, but not really sure where to tap revers light power. I'd love to just connect to the reverse lights and then add power from the switch elsewhere. I doubt the factory reverse wires are spout enough to add a big light to. Anyone think that would be OK.



Anyone know where to find the reverse light circuit up near the cab or engine?

The reverse light circuit isn't stout enough, that's why you want to run it thru your relay. The relay then takes the extra current.



You have an auto transmission, so there will be a wire in the steering column, and will go down under the dash. Get a test light, and you'll have to start fishing around for it. Just be careful with ECM and Airbag wires.



It's dark out now, so I can't go look. I'll try on Monday.



SOLER

 

[dieselshu]

aux back up lighting

someone else posted this information on another thread...

IPF

Look under accessories, they a have a three way lighted LED toggle switch for $15 or you can by there whole kit with wiring harness and eveything thing for $150.

This is the only place I could find that had a lighted LED three way toggle switch.

Hope this helps.



Dave

 

[DFrank]

Thanks for all the tips. They are in and they work great. The install was sort of a PITA, but pretty straight forward. As SOLER said the hardest part was routing all of the wires, especially the ones I ran inside my lumber rack. Did the whole thing for around 60 bucks. I'll try to put some pics in my gallery next week.