As a newbie, I hope I am in the correct forum for my question. If not, my apologies and please direct me to the proper location.

I have a 2010 Dakota Big Horn with factory fog lights in the bumper. I would like to intsall a set of Hella 500's behind the grill and control them with the existing fog light switch.

If I locate the power wire for the existing fogs, can I use that to power the new Hellas? Would I need to tap into the power wire at the right fog to power the added right side Hella and then do the same for the left side or can I just make one power tap to energize both Hellas?

Finally, will I be creating any problems with circuit overloads or messing up the truck's computer by this method of wiring the new fog lights?

Thanks to all for your help!!

 

You are on the right track for your thinking, it would be nice to just tap into the lights and use that, but that may well overload the intended load of the wire. The best idea would be to install a relay off of the lights so when the lights get turned on the relay flips and turns on your extra fog lights.

Especially if you are running high wattage Hellas, you will want a relay.

 

DM_kota:

Thanks for the input. So, I power the relay from the positive wire for the original fog lights, take power from the battery and wire the Hellas up to the relay. When I turn on the switch for the original fogs, the relay is energized and power goes to the Hellas.

Brilliant!!

Sometimes I guess I try to oversimplify things. Your idea makes perfect sense to minimize the load on the original fog light circuit.

Thanks for the help!

 

Here is a great addition to that! Buy a Extension cable for the OEM fogs (come in pairs) and Tap into that for your Relay. Then you can remove it if any issues arise, and if it gets corroded / damaged its a simple replacement/removal

The extension fits between the OEM Connector at the Fog Light, and the Bulb.

 

Like this. I used them before, and Modified them to work with my HID's after (Swapped +/-) as the HID were reversed to the Harness

http://www.ebay.ca/itm/9145-H10-9005...item3f19210736

 

Don't do it!!! I tried the exact thing just spliced into both fog lights, the power was heavily reduced. Just buy a power switch off of amazon or eBay, you'll be better off and can still use your stock fog lights

 

I would agree with you if you were going to splice the add-on lamp power into the fog-light power line, but splicing into the fog light line to power one relay activation coil should take insignificant power - the power to light the add-on lamps would come from the battery via the relay switch, so the fog-light line would experience very little change in it's amperage draw. If the addition of anything to that circuit causes the lights to dim, I'd suspect a bad splice, bad ground, or an oversize fuse (if the connection is good and the current draw is so high as to dim the lights, the fuse should blow, otherwise the wires would overheat).

If you want less current draw, use a solid-state relay or make a simple solid state switch using a Mosfet (I prefer the NPN) - lots of info on line to see how this works.

 

It think he meant he powered 2 Addition lights off the Fogs, Without a Relay. (1 Light per Fog I assume)

And true the use of the relay wouldnt cause it, as it draws so little. Since the Battery powers the Lights, The Fog Positive just trips the relay