Back-Up Light Question

[MYT1]

I would like to add after-market back-up lights to my truck.

I would like to have them wired with some sort of three way switch.

I would like to be able to have the lights come on automatically when ever I shift into reverse.

And I would also like to be able to turn the lights on and off separately from inside the cab.

I heard that there is such a switch, but I have no idea what to look for, or what it is called.

Thanks.

 

[Mr. Snappy]

Well, I'm no wiring guru, but I think you need a single pole, two way switch. And I'd probably try to pull power from the reverse light circuit on a constant hot, running power to the switch, then to the lamps.
But, if I was doing it, it would involve lots of trial and error, and rework, and that sort of thing.
Wiring is not my strong point

 

[4x4junkie]

You will need a single-pole/double-throw (SPDT) switch w/center-off position, and of course a lighting relay to go with it.

Up would be "always on", down is "on w/reverse", and center is "always off".

A diagram to help (substitute your reverse lights for the head lights part)

 

[1stDeuce]

Several ways to do this...
The easiest is probably to use LED flood lights for your aux backup lights. Power them off the standard backup light wiring, right at the back of the truck, but put a large diode between the lamps and factory wiring. Then run a separate power wire from your switch in the cab to the lights. If you stay with relatively low wattage lights, like the $20 or less ~20w lights on Amazon or Ebay, there's really no need for a relay in any of it. (40 watts of lights is less than 4 amps, so not a huge draw... Put a 5 or 10A fuse right were you tap power for the switch just to be safe.

This way, you can turn on the lights any time with the switch, or they'll just come on automatically when you shift to reverse. The diode prevents the truck backup lamps from coming on when you switch the aux lamps on manually.

Make sense?

Oh, I've been outdone with a cool diagram... I'll have to sketch one up now...

 

[lugueto]

The three way switch is exactly the one you're after.

Always allow for an off position with lights.

So you'll be left with one of the switch's "On" positions with a circuit wired to the reverse circuit via a relay, for the lights to come on automatically. You can leave the switch in this position all the time if you like.

Then you wire the other "On" position with a simple, always-hot circuit wired directly to the battery or aux fuse box for when you need the lights with the vehicle off, or without having to switch the transmission to reverse.

The off position will allow you to turn the lights off when needed, say, when backing up without wanting to unnecessarilly blind the person or vehicle behind you.

 

[1stDeuce]

The off position will allow you to turn the lights off when needed, say, when backing up without wanting to unnecessarilly blind the person or vehicle behind you.

Flip side: If you're backing up, and there's a vehicle or person behind you, the extra lights will make clear your intentions... GTFOOTW!!

Like I said, there are LOTS of ways to go about it. Just depends on what you want, and how much wiring you want to do.

Here's a wiring diagram of my simpler way. (oops, forgot to attach it when I originally posted.)



Keeping aux lamp power under 50W total keeps the draw under 5A total. I have two 18W lights on my camper as yard lights. One is plenty of light!!

The diodes are available cheap on epay, just search for "5A diode". A 60V rated diode will work fine. The grey stripe goes toward the aux lights.

 

[MYT1]

Thank you so much.

This is just the information I was hoping for.

 

[warwickscout]

rigid sells a wiring harness just for that.i have it on my f150 .

 

[M35A2]

You want a single pole, double throw switch. SPDT.

One leg of the switch will tie your auxiliary b/u lights to your existing reverse light circuit.

The other leg will directly energize them from the battery (if you want them to work with the engine off) or a line that is hot with the ignition on.

Whether or not you need a relay in the circuit depends on how much power your aux b/u lights require. Less than 60 watts, typically you are OK without a relay.

You don't need diodes with this approach. You will only need one regular Bosch relay if your aux lights are above 60 watts.

 

[Sabre]

1stDeuce, above (with the diode) describes a very simple circuit that only requires one wire from the cockpit to the rear of the vehicle.

M35A2, above (with only a SPDT switch) describes a very simple circuit that only requires one of two things: (1) a wire from the backup light power feed run forward to the cockpit switch (2 power leads running the length of the rig), or (2) power for the transmission backup circuit taken off (tapped into) somewhere under the dash or in the transmission tunnel.

BTW, installing a diode is very, very simple. Here's one I installed on a motorcycle lighting project. I crimped & soldered connectors onto the diode leads and plugged them into an inline fuse holder. Super easy.

 

[4x4junkie]

You might consider an obnoxious illuminated switch or similar, you dont need to forget switching off whilst driving only to have Police remind you of it.

One variation I know of, a wind up timer served as the 'aux switch.
Turn up the expected duration, then if forgotten, just switches its self off hopefully before Police serve reminder...

Just the reason for the indicator LED on the diagram I posted earlier (the switches are standard SPDT mini-toggles).

 

[rayra]

OP needs to be aware that extra backup lights that are high and bright will usually net a ticket on the road. Likewise if he uses the separate circuit to blind someone on the road behind him, when not shifting into reverse.

 

[lugueto]

Flip side: If you're backing up, and there's a vehicle or person behind you, the extra lights will make clear your intentions... GTFOOTW!!

True, but the on-off-on switch will give you this option (both with or without putting the vehicle in reverse) if need be and the option of avoiding it if you don't want to make your intentions clear.

 

[Ducky's Dad]

My bigass backup lights are on separate toggles or rockers, not connected to the trans reverse switch or to the factory backup lights. I positioned the switches so that I can easily reach them while I'm looking back, and they all have big indicator lights so that I don't accidentally leave them on when I'm driving. No fancy wiring or diodes or resistors, no confusing the trucks' computers, just a switch and a relay. Simple and effective. Two trucks are running Hella Euro halogen low-beam headlights on the rear, one is running a pair of diffused Ridgid Dually D2 LEDs, and the other has six 55W Hellas with different patterns for maximum utility.

 

[MOguy]

OP needs to be aware that extra backup lights that are high and bright will usually net a ticket on the road. Likewise if he uses the separate circuit to blind someone on the road behind him, when not shifting into reverse.

Somebody mentioned an illuminated switch. That would help so you don't leave the light on accidentally. I have a separate back up light that is 55w so it isn't brighter than a headlight and I have forgot and left mine on many times.

Mine is on a switched accessory, not even sure what size fuse. I should probably check but I have had it hooked up for over a decade and no issues.