Auto Electrical Question???

[Durango005]

Hi, I was wondering how you would go about hooking up lights (Ex. Amber marking lights) so that they can run with your OEM ambers or manually by a switch. I made up a diagram of what I thought could work, basically 2 separate triggers for a light . Feel free to criticize it, I've never wired anything like this.

[shorod]

How much current do the aux lights draw that you are planning to use?

With those SPDT relays, you should be able to do what you want to with a single relay. Have the lights connected to terminal 30. Connect the normal marker lights to terminal 87a. This way, when the manual switch is open, the parking lights also power the aux lights. If you wish to turn on the aux lights manually, then you flip the switch and the aux lights get power through your fused wire to the battery. You might consider using a circuit for your manual switch that is only powered with the key on so that if you forget to turn off the manual switch, they automatically shut off with the key. If you are switching a hot lead, be sure to fuse it appropriately as well.

-Rod

[Durango005]

There 12v lights doesn't really give me much info online. http://www.harborfreight.com/cpi/cta...emnumber=98933

Thank you for your response!

[Durango005]

I tried putting a diagram together with what you said, please correct me if I'm wrong.

[shorod]

Not quite. On your SPDT relay, terminals 85 and 86 are the coil. The coil is what switches the relay contacts. When there is insufficient voltage potential difference across terminals 85 and 86, terminals 30 and 87a are shorted. When a sufficient potential difference is applied across terminals 85 and 86, the coil "throws" the switch to terminal 87, causing a short between 30 and 87.

So, you'll want to have the added running lights connected to terminal 30 of the relay. Then, assuming the factory parking light circuit can source sufficient current for the added lights, connect terminal 87a to the factory parking light circuit. This way, when you turn on your parking lights, your added running lights will also come on.

Connect terminal 85 (or 86) to ground. Connect terminal 86 (or 85) to one pole of your manual switch. The other pole of your manual switch should connect to a fused circuit that is only powered when the key is in the run/ACC position. This way, when you close the manual switch, your relay coil will now be energized and short contact 30 and 87. This leaves the connection to terminal 87, which you probably realize needs to be connected through a fuse to battery voltage.

What this above configuration won't allow is a way to disable the running lights when the head/parking lights are on. If you want to have that option, you could add a second switch (or an on-off-on switch) to the circuit to open the ground to the relay coil.

It concerns me a bit that the instructions for the lights make no mention of current draw or fusing the circuit. You wouldn't want an issue in the added light circuit to cause the headlights to fail! As a rough estimate, you could measure the DC resistance across one of the bulbs, multiply that by 12 (or however many bulbs you plan to add), then add 20% or so to get an idea how much current you might expect these lights to draw which will help you determine an appropriate fuse rating as well as determining if the parking light circuit can support the added load. If these were LED lights, I wouldn't be concerned. But adding 12 incandescent bulbs is probably more than you should expect the original parking light circuit to support. In that situation, you can either go the dual relay route, or add a diode and use move some wires around. If you're interested in that approach, let me know and I'll try to draw a picture up.

-Rod

[Durango005]

Ok, I think I've finally got it. How's this look?

[shorod]

That should work as long as 1) Your parking/headlight circuit can support the added load, and 2) You don't have the need to disable the running lights and still have your parking/headlights on. I also continue to suggest that the "12V Power w/ fuse" is switched power (ie: only on when the key is on).

-Rod

[Durango005]

Ok, thanks a lot for your help!