Electrical Guru needed - Reverse Light with switch for work lamp?

[badfysh]

Hello,

I need help from an experienced electrical engineer or otherwise that can explain how to set this up.....

I am replacing my "reverse" light with two LED work lamp style lights attached to my rack. I also want to add a switch so that when I am in the back working, I can turn the lights on. So Ultimately I want one (two total) light system for two functions.

1. On when I am in reverse.
2. On when I flip a switch in the trunk to use as a work light.

Is this as simple as adding another +12v line with a switch to the light? Or will this damage something? It seems to me that 12v coming form the system is just that, and whether it comes from one place (the car reverse) or straight from 12v with a switch, it shouldn't matter...but I don't want to fry the computer or burn the car down. What if I leave the switch on and then forget then go to drive away and put it in reverse ie: two 12v sources in parallel running to the same light, again, shouldn't matter right? See, I need help.

Currently I have a "work lamp" attached to the rack and it is just scotch locked onto the reverse light pig tail (reverse went away with the factory bumper).

A diagram would be helpful if this setup is anything beyond just simple wiring.

Thank you.

 

[pugslyyy]

In theory it should work fine, but it certainly would not be a best practice to have 2 separate power sources (with 2 separate fuses) for a circuit.

An alternative could be adding a switch that bypasses the reverse sensor (normally open, but you close it when you want the work light to come on).

 

[badfysh]

Couldn't I then just splice at the existing pigtail for reverse signal and add 3way switch with one side being the reverse signal and other side being work light 12v ?

So, in the "off" position, its the reverse, in the "on", it'd the work lamps

 

[anickode]

I did mine by feeding the LEDs both from a 12v switched line and from the reverse lights, and put a diode between the LEDs and the factory reverse lamps. Reverse lights both sets, switch lights only the LEDs.

 

[badfysh]

I'm not using factory lamps anymore, they are gone.

On a 04 D2 the reverse lamps are[were] in the rear bumper and that was removed.

So now I just have the work lamp on the rack and its spliced into reverse pigtail, but it can't light manually.

I'm replacing that single reverse on the rack, with two LED's, rigid 2x2's, one at each corner.

But I don't just want reverse, I want them switched for on demand work area lighting.

 

[jeffjeeptj]

Buy a single pole, double throw switch. Most easily found is called center off. The switch will have three connectors on the back. When the switch is in the "up" position, the there will be continuity between the center connector and one of the outer connector. With the switch all the way in the other direction, "down", there will be continuity between the center and the other outer connector. With the switch in the center (off) position, there will be no continuity.
So, hook up the switch center connector to the lamps, one of the outer connectors to the reverse light wire, and the other outer connector to 12v positive (assuming negative ground). You decide how to position the switch so it works for you (up is battery, down is reverse, or any other up/down or left/right handle position you like.
Remember to put a fuse in the battery hot line to the switch, near your 12volt battery connection.

If you can only find a double throw, double pole, that will work, it will have 6 connectors on the back. just use the three connectors on the same aide of the switch.
Sorry about photo orientation. I'm better at wiring than photos on a forum

 

[badfysh]

OK, thanks, that's what I needed.

 

[4x4junkie]

Pretty much as jeffjeeptj explained, 'xept I'm using a relay for the lights. Switch up is On-always, sw down is On-w/reverse, sw in middle is Off-completely.

Wiring diagram (substitute 12V from reverse light circuit for the headlamp circuit)

 

[jeffjeeptj]

I do like relays. Extremely useful for managing higher amp circuits and keeping switch panel wiring simpler and neater. I tried to keep it simple, hopefully one of these two replies helped.
Let us have some photos

 

[TiFJ]

I haven't done this yet but plan on doing it shortly. I think the easiest way to do this is with an SPDT relay:

Wired as follows:
#85--Ground.
#86--Reverse light (+)
#87--12V Battery (+).
#87A--Switch (+)(will need to be relayed and fused separately)
#30--Light bar (+).

 

[psykokid]

Once I get mine figured out Joe I'll let you check it out. Going to use either a relay with a switch to bridge the power leads or two relays with a switch. Depends on if i use an LED light or an old Hella work lamp I have sitting around. Relay + switch for LED and two relays + switch for halogen.